Physics
New submissions
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New submissions for Thu, 2 May 24
- [1] arXiv:2405.00002 [pdf, ps, other]
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Title: Reconfigurable nonreciprocal heat transport with natural bulk materialsComments: 34 pages, 15 figuresSubjects: Applied Physics (physics.app-ph)
Non-reciprocity is increasingly scrutinised in contemporary physics and engineering, especially in the realm of heat transport. This concept opens up novel avenues for directional heat transport and thermal regulation. Nonetheless, the development of non-reciprocal thermal metamaterials confronts three primary challenges: a constrained operational temperature range and structural scale, considerable energy dissipation, and the limitation of non-reciprocal effects due to external parameters that are not freely adjustable. To surmount these hurdles, we propose a reconfigurable approach to non-reciprocal heat transport. The design features a simple asymmetrical structure, with a flat panel made of natural, evenly-distributed material, positioned vertically on one side of a central horizontal board.We employ natural convection on the vertical plate to facilitate non-reciprocal heat transport. The reconfigurability of non-reciprocal heat transport is achieved by adjusting the number of vertical plates and their thermal conductivity. Theoretical computations of the rectification ratio are employed to quantify and forecast the non-reciprocal effect, corroborated by simulations and empirical studies. We also establish correlations between the rectification ratio and various parameters, including the vertical plates' positioning and height, ambient temperature, and the temperature differential between heat sources. Control over multiple parameters can efficaciously widen the scope of non-reciprocal control and streamline experimental procedures. Furthermore, our research exclusively utilises the natural convection of air for non-reciprocal heat transport, obviating the need for Supplementary energy sources and markedly enhancing energy efficiency.
- [2] arXiv:2405.00008 [pdf, other]
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Title: Cross-platform impact of social media algorithmic adjustments on public discourseSubjects: Physics and Society (physics.soc-ph)
In the hypertrophic and uncharted information world, recommender systems are gatekeepers of knowledge. The evolution of these algorithms is usually an opaque process, but in February 2023, the recommender system of X, formerly Twitter, was altered by its chairman (Elon Musk) transparently, offering a unique study opportunity. This paper analyses the cross-platform impact of adjusting the platform's recommender system on public discourse. We focus on the account of Elon Musk and, for comparison, the account of the President of the United States (Joe Biden). Our results highlight how algorithm adjustments can boost content visibility, user engagement, and community involvement without increasing the engagement or involvement probabilities. We find that higher visibility can increase the influence on social dialogue but also backfire, triggering negative community reactions. Finally, our analysis offers insights to detect future less transparent changes to recommender systems.
- [3] arXiv:2405.00014 [pdf, other]
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Title: Explaining Grover's algorithm with a colony of ants: a pedagogical model for making quantum technology comprehensibleComments: 18 pages, 4 figuresSubjects: Popular Physics (physics.pop-ph); Quantum Physics (quant-ph)
The rapid growth of quantum technologies requires an increasing number of physicists, computer scientists, and engineers who can work on these technologies. For educating these professionals, quantum mechanics should stop being perceived as incomprehensible. In this paper we contribute to this change by presenting a pedagogical model for explaining Grover's search algorithm, a prominent quantum algorithm. This model visualizes the three main steps of Grover's algorithm and, in addition to explaining the algorithm itself, introduces three key principles of quantum mechanics: superposition, interference, and state collapse at measurement. The pedagogical model, visualized by a video, is called the "Ant Colony Maze model". It represents the search problems as finding the exit of a maze, and visualizes Grover's search algorithm as a strategy by which a colony of ants finds that exit.
- [4] arXiv:2405.00019 [pdf, ps, other]
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Title: Cycling on rough roads: A model for resistance and vibrationAuthors: Miles M. TurnerJournal-ref: Vehicle System Dynamics 2024Subjects: Popular Physics (physics.pop-ph); Biological Physics (physics.bio-ph); Classical Physics (physics.class-ph)
Minimising opposing forces is a matter of interest to most cyclists. These forces arise from passage through air ("drag") and interaction with the road surface ("resistance"). Recent work recognises that resistance forces arise not only from the deformation of the tyre ("rolling resistance") but also from irregularities in the road surface ("roughness resistance"), which lead to power dissipation in the body of the rider through vibration. The latter effect may also have an adverse impact on human health. In this work we offer a quantitative theory of roughness resistance and vibration that links these effects to a surface characterisation in terms of the International Roughness Index (IRI). We show that the roughness resistance and the Vibration Dose Value (or VDV, the usual vibration dosage metric) can be expressed in terms of elementary formulae. The roughness resistance depends only on the vertical stiffness of the bicycle and the roughness index. Surprisingly, other apparently relevant parameters, such as physiological characteristics of the bicycle rider and other features of the bicycle, do not enter. For roads of moderate roughness, roughness resistance is larger than rolling resistance. For very rough roads, roughness resistance is larger than aerodynamic drag. So only on roads of high quality (in most jurisdictions, accounting for less than 10~\% of the total) can roughness resistance be ignored. Roughness resistance can be mitigated by reducing the vertical stiffness of the bicycle. In common with other recent reports, we find that almost any cycling activity will breach public health guidelines relating to Vibration Dose Value.
- [5] arXiv:2405.00020 [pdf, other]
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Title: Technosignatures longevity and Lindy's lawComments: 9 pages, 4 figuresJournal-ref: The Astronomical Journal, 167, 119 (2024)Subjects: Popular Physics (physics.pop-ph); Instrumentation and Methods for Astrophysics (astro-ph.IM)
The probability of detecting technosignatures (i.e. evidence of technological activity beyond Earth) increases with their longevity, or the time interval over which they manifest. Therefore, the assumed distribution of longevities has some bearing on the chances of success of technosignature searches, as well as on the inferred age of technosignatures following a first contact. Here, we investigate the possibility that the longevity of technosignatures conforms to the so-called Lindy's law, whereby, at any time, their remaining life expectancy is roughly proportional to their age. We show that, if Lindy's law applies, the general tenet that the first detected technosignature ought to be very long lived may be overruled. We conclude by discussing the number of emitters that had to appear, over the history of the Galaxy, in order for one of them to be detectable today from Earth.
- [6] arXiv:2405.00022 [pdf, other]
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Title: News ecosystem dynamics: Supply, Demand, Diffusion, and the role of DisinformationSubjects: Physics and Society (physics.soc-ph)
The digital age provides new challenges as information travels more quickly in a system of increasing complexity. But it also offers new opportunities, as we can track and study the system more efficiently. Several studies individually addressed different digital tracks, focusing on specific aspects like disinformation production or content-sharing dynamics. In this work, we propose to study the news ecosystem as an information market by analysing three main metrics: Supply, Demand, and Diffusion of information. Working on a dataset relative to Italy from December 2019 to August 2020, we validate the choice of the metrics, proving their static and dynamic relations, and their potential in describing the whole system. We demonstrate that these metrics have specific equilibrium relative levels. We reveal the strategic role of Demand in leading a non-trivial network of causal relations. We show how disinformation news Supply and Diffusion seem to cluster among different social media platforms. Disinformation also appears to be closer to information Demand than the general news Supply and Diffusion, implying a potential danger to the health of the public debate. Finally, we prove that the share of disinformation in the Supply and Diffusion of news has a significant linear relation with the gap between Demand and Supply/Diffusion of news from all sources. This finding allows for a real-time assessment of disinformation share in the system. It also gives a glimpse of the potential future developments in the modelisation of the news ecosystem as an information market studied through its main drivers.
- [7] arXiv:2405.00032 [pdf, ps, other]
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Title: Tight Non-Radiating Bends of 3D-Printed Dielectric Image Lines Based on Electromagnetic Bandgap MirrorsSubjects: Applied Physics (physics.app-ph); Optics (physics.optics)
This paper reports on a novel compact, low-loss bending technique for additively manufactured dielectric image lines between 140 GHz and 220 GHz. Conventional bending approaches require either large curvature radii or technologically challenging permittivity variations to prevent radiation loss at line discontinuities, e.g. caused by narrow bends. In contrast, this work uses extremely compact, easy-to-manufacture electromagnetic bandgap (EBG) cells to solve the afore mentioned challenge for the first time. These offer excellent reflection properties and thus enable broadband and low-loss (IL < 1 dB) guidance of electromagnetic waves by means of total reflection. Without increasing the complexity of the process, both the high-pass behaviour and the enormous space requirement of conventional dielectric bends are completely avoided. In addition, the use of EBGs improves the mutual isolation of dielectric image lines of up to 30 dB. Therefore, a promising solution for the realization of narrow, 3D-printed, low-loss signal distribution networks in the sub-THz domain is offered.
- [8] arXiv:2405.00033 [pdf, ps, other]
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Title: One-way Valley-locked waveguide with large channel achieved by all-dielectric Photonic CrystalsAuthors: Li Liang, Xiao Zhang, Chuan Wang, Jie Liu, Longzhen Fan, Chengpeng Liang, Liang Liang, Feifei Li, Qi Wu, Yin PooComments: 16 pages and 5 figuresSubjects: Applied Physics (physics.app-ph); Optics (physics.optics)
Nonreciprocity, which denotes the asymmetric or even unidirectional transmission of light, constitutes the cornerstone of modern photonic circuits. In the realm of photonic devices, it has been widely utilized in isolators, circulators and so on. Recent topology in artificial materials, an unprecedented degree of freedom, has been proposed to solve the effect of impurities on nonreciprocal transmission. However, in view of the bulk-edge correspondence, the spatial width of the transmission channel with uniform field distribution is quite narrow and needs further exploration. In this paper, we proposed a one-way valley-locked waveguide with a large channel in an all-dielectric photonic crystal. Quite different from the topological edge modes, the unidirectional property of our waveguide comes from the bulk modes with valley-lock, which can fully utilize the whole dimension of the structure with an efficiency of 100%. Additionally, the electrical field is uniformly distributed across the entire channel, which opens a new avenue for low-loss nonreciprocity devices.
- [9] arXiv:2405.00034 [pdf, ps, other]
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Title: Directed High-Energy Infrared Laser Beams for Photovoltaic Generation of Electric Power at Remote LocationsComments: 14 pages, 11 FiguresSubjects: Applied Physics (physics.app-ph); Optics (physics.optics)
Transferring energy without transferring mass is a powerful paradigm to address the challenges faced when the access to, or the deployment of, the infrastructure for energy conversion is locally impossible or impractical. Laser beaming holds the promise of effectively implementing this paradigm. With this perspective, this work evaluates the optical-to-electrical power conversion that is created when a collimated laser beam illuminates a silicon photovoltaic solar cell that is located kilometers away from the laser. The laser is a CW high-energy Yb-doped fiber laser emitting at a center wavelength of 1075 nm with ~1 m2 of effective beam area. For 20 kW illumination of a solar panel having 0.6 m2 of area, optical simulations and thermal simulations indicate electrical output power of 3000 Watts at a panel temperature of 550 K. Our investigations show that thermo-radiative cells are rather inefficient. In contrast, an optimized approach to harvest laser energy is achieved by using a hybrid module consisting of a photovoltaic cell and a thermo-electric generator. Finally, practical considerations related to infrared power beaming are discussed and its potential applications are outlined.
- [10] arXiv:2405.00035 [pdf, ps, other]
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Title: Experimental and Numerical Validation of Tape-Based Metasurfaces in Guiding High-Frequency Surface Waves for Efficient Power TransferAuthors: K. Suzuki, P. T. Dang, H. Homma, A. A. Fathnan, Y. Ashikaga, Y. Tsuchiya, S. Phang, H. WakatsuchiSubjects: Applied Physics (physics.app-ph)
We present an effective method for transmitting electromagnetic waves as surface waves with a tape-based metasurface design. This design incorporates silver square patches periodically patterned on an adhesive tape substrate. Specifically, our study proposes a strategy to enhance the efficiency of power transfer in high-frequency bands by guiding signals as surface waves rather than free-space waves. Both the numerical and experimental results validate the markedly enhanced efficiency in power transfer of high-frequency signals compared to that achieved with conventional methods, such as wireless power transfer and microstrips. Importantly, our metasurface design can be readily manufactured and tailored for various environments. Thus, our study contributes to designing power-efficient next-generation communication systems such as 6G and 7G, which leverage high-frequency signals in the millimeter-wave and THz bands.
- [11] arXiv:2405.00036 [pdf, other]
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Title: Spatio-temporal load shifting for truly clean computingSubjects: Physics and Society (physics.soc-ph); Computers and Society (cs.CY)
Companies with datacenters are procuring significant amounts of renewable energy to reduce their carbon footprint. There is increasing interest in achieving 24/7 Carbon-Free Energy (CFE) matching in electricity usage, aiming to eliminate all carbon footprints associated with electricity consumption on an hourly basis. However, the variability of renewable energy resources poses significant challenges for achieving this goal. We explore the impact of shifting computing jobs and associated power loads both in time and between datacenter locations. We develop an optimization model to simulate a network of geographically distributed datacenters managed by a company leveraging spatio-temporal load flexibility to achieve 24/7 CFE matching. We isolate three signals relevant for informed use of load flexiblity: varying average quality of renewable energy resources, low correlation between wind power generation over long distances due to different weather conditions, and lags in solar radiation peak due to Earth's rotation. We illustrate that the location of datacenters and the time of year affect which signal drives an effective load-shaping strategy. The energy procurement and load-shifting decisions based on informed use of these signals facilitate the resource-efficiency and cost-effectiveness of clean computing -- the costs of 24/7 CFE are reduced by 1.29$\pm$0.07 EUR/MWh for every additional percentage of flexible load. We provide practical guidelines on how companies with datacenters can leverage spatio-temporal load flexibility for truly clean computing. Our results and the open-source optimization model can also be useful for a broader variety of companies with flexible loads and an interest in eliminating their carbon footprint.
- [12] arXiv:2405.00039 [pdf, ps, other]
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Title: Tuning the response of bubble-based metamaterials with short transient pulsesComments: 11 pages, 5 figuresSubjects: Applied Physics (physics.app-ph)
Bubble-based metamaterials have been extensively studied both theoretically and experimentally thanks to their simple geometry and their ability to manipulate acoustic waves. The latter is partly dependent on the structural characteristics of the metamaterial and partly dependent on the incident acoustic wave. Initially, the selection of specific structural characteristics is explained by presenting the Fourier transformations of the reflected waves for different arrangements of a bubbly meta-screen subject to Gaussian excitation. Next, our numerical study focuses on the changes induced to the response of a bubbly meta-screen, subject to different excitation pulses. For complex-frequency excitation the bubbles delay to return to their equilibrium position for a couple of moments, hence the energy is stored in the system during those moments. This research provides a new strategy to actively control the response of a bubbly meta-screen and seeks to inspire future studies towards further optimization of the incident pulse based on the functionalities in need.
- [13] arXiv:2405.00041 [pdf, other]
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Title: A theory of best choice selection through objective arguments grounded in Linear Response Theory conceptsComments: 25 pages, 2 figures, 5 tables, 72 references; accepted in a Special Issue of the journal Physics in honor of Serge Galam for his 70th birthday and 40 years of SociophysicsSubjects: Physics and Society (physics.soc-ph); Statistical Mechanics (cond-mat.stat-mech); Information Theory (cs.IT)
In this paper, we propose how to use objective arguments grounded in statistical mechanics concepts in order to obtain a single number, obtained after aggregation, which would allow to rank "agents", "opinions", ..., all defined in a very broad sense. We aim toward any process which should a priori demand or lead to some consensus in order to attain the presumably best choice among many possibilities. In order to precise the framework, we discuss previous attempts, recalling trivial "means of scores", - weighted or not, Condorcet paradox, TOPSIS, etc. We demonstrate through geometrical arguments on a toy example, with 4 criteria, that the pre-selected order of criteria in previous attempts makes a difference on the final result. However, it might be unjustified. Thus, we base our "best choice theory" on the linear response theory in statistical mechanics: we indicate that one should be calculating correlations functions between all possible choice evaluations, thereby avoiding an arbitrarily ordered set of criteria. We justify the point through an example with 6 possible criteria. Applications in many fields are suggested. Beside, two toy models serving as practical examples and illustrative arguments are given in an Appendix.
- [14] arXiv:2405.00042 [pdf, ps, other]
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Title: Is Artificial Intelligence the great filter that makes advanced technical civilisations rare in the universe?Authors: Michael GarrettComments: 9 pages, no figures. Accepted for publication by Acta Astronautica, March 2024Subjects: Popular Physics (physics.pop-ph); Physics and Society (physics.soc-ph)
This study examines the hypothesis that the rapid development of Artificial Intelligence (AI), culminating in the emergence of Artificial Superintelligence (ASI), could act as a "Great Filter" that is responsible for the scarcity of advanced technological civilisations in the universe. It is proposed that such a filter emerges before these civilisations can develop a stable, multiplanetary existence, suggesting the typical longevity (L) of a technical civilization is less than 200 years. Such estimates for L, when applied to optimistic versions of the Drake equation, are consistent with the null results obtained by recent SETI surveys, and other efforts to detect various technosignatures across the electromagnetic spectrum. Through the lens of SETI, we reflect on humanity's current technological trajectory - the modest projections for L suggested here, underscore the critical need to quickly establish regulatory frameworks for AI development on Earth and the advancement of a multiplanetary society to mitigate against such existential threats. The persistence of intelligent and conscious life in the universe could hinge on the timely and effective implementation of such international regulatory measures and technological endeavours.
- [15] arXiv:2405.00043 [pdf, other]
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Title: Shrinking a gradient index lens antenna system with a spaceplateSubjects: Applied Physics (physics.app-ph); Optics (physics.optics)
The miniaturisation of optical systems is an ongoing challenge across the electromagnetic spectrum. While the thickness of optical elements themselves can be reduced using advances in metamaterials, it is the voids between these elements -- which are necessary parts of an optical system -- that occupy most of the volume. Recently, a novel optical element coined a `spaceplate' was proposed, that replaces a region of free space with a thinner optical element that emulates the free-space optical response function -- thus having the potential to substantially shrink the volume of optical systems. While there have been a few proof-of-principle demonstrations of spaceplates, they have not yet been deployed in a real-world optical system. In this work, we use a bespoke-designed spaceplate to reduce the length of a gradient index (GRIN) lens microwave antenna. Our antenna is designed to operate at 23.5 GHz, and the incorporation of a nonlocal metamaterial spaceplate enables the distance between the antenna feed and the GRIN lens to be reduced by almost a factor of two. We find the radiation patterns from a conventional and space-squeezed antenna are very similar, with a very low cross-polarisation, and only a minor increase in the side-lobe levels when introducing the spaceplate. Our work represents a first example of a spaceplate integrated into a functional optical system, highlighting the potential for this concept to reduce the physical size of optical systems in real-world applications.
- [16] arXiv:2405.00044 [pdf, ps, other]
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Title: Airbus A32x vs Boeing 737 Safety OccurrencesAuthors: Graham WildComments: 7 pages, 15 figuresJournal-ref: IEEE Aerospace and Electronic Systems Magazine (2023)Subjects: Physics and Society (physics.soc-ph)
Safety is the priority for airlines. Airlines are sensitive to passengers' perceptions of safety, having randomly assigned the Boeing 737 Max to routes and times. Historically, Boeing has been considered more reliable and safer than Airbus. Hence, it is worth asking the question, are there any differences in the safety occurrences of the core narrow-body single-aisle aircraft of Boeing and Airbus; the 737 and A32x families of aircraft. Utilizing the International Civil Aviation Organization safety occurrence data, from 2008 to 2019, these aircraft were compared in terms of occurrence type, occurrence category, phase of flight, injury level, and fatalities. It was found that Boeing had more accidents than expected, while Airbus had less (p=0.015). In terms of fatalities Boeing has had more than expected, with Airbus less (p<0.001). Looking at just accidents, only the number of fatalities was statistically significantly different. In both cases, the increased number of fatalities for Boeing appears to be the result of the two recent Boeing 737 Max accidents. Looking at the reported fatal and hull loss accident rates, it was also found that the annual reduction for the Airbus A32x aircraft were better than for the Boeing 737 aircraft.
- [17] arXiv:2405.00045 [pdf, ps, other]
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Title: Does there exist the applicability limit of PDE to describe physical phenomena? -- A personal survey of Quantization, QED, TurbulenceAuthors: Atsushi InoueComments: 27pagesSubjects: General Physics (physics.gen-ph)
What does it mean to study PDE(=Partial Differential Equation)? How and what to do "to claim proudly that I'm studying a certain PDE"? Newton mechanic uses mainly ODE(=Ordinary Differential Equation) and describes nicely movements of Sun, Moon and Earth etc. Now, so-called quantum phenomenum is described by, say Schr\"odinger equation, PDE which explains both wave and particle characters after quantization of ODE. The coupled Maxwell-Dirac equation is also "quantized" and QED(=Quantum Electro-Dynamics) theory is invented by physicists. Though it is said this QED gives very good coincidence between theoretical and experimental observed quantities, but what is the equation corresponding to QED? Or, is it possible to describe QED by "equation" in naive sense?
- [18] arXiv:2405.00046 [pdf, ps, other]
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Title: Synchronization in a market model with time delaysComments: 12 pages, 4 figuresSubjects: Physics and Society (physics.soc-ph); Statistical Finance (q-fin.ST)
We examine a system of N=2 coupled non-linear delay-differential equations representing financial market dynamics. In such time delay systems, coupled oscillations have been derived. We linearize the system for small time delays and study its collective dynamics. Using analytical and numerical solutions, we obtain the bifurcation diagrams and analyze the corresponding regions of amplitude death, phase locking, limit cycles and market synchronization in terms of the system frequency-like parameters and time delays. We further numerically explore higher order systems with N>2, and demonstrate that limit cycles can be maintained for coupled N-asset models with appropriate parameterization.
- [19] arXiv:2405.00047 [pdf, ps, other]
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Title: The Quantum Dynamics of Cost Accounting: Investigating WIP via the Time-Independent Schrodinger EquationAuthors: Maksym LazirkoSubjects: Physics and Society (physics.soc-ph); General Finance (q-fin.GN); Quantum Physics (quant-ph)
The intersection of quantum theory and accounting presents a novel and intriguing frontier in exploring financial valuation and accounting practices. This paper applies quantum theory to cost accounting, specifically Work in Progress (WIP) valuation. WIP is conceptualized as materials in a quantum superposition state whose financial value remains uncertain until observed or measured. This work comprehensively reviews the seminal works that explored the overlap between quantum theory and accounting. The primary contribution of this work is a more nuanced understanding of the uncertainties involved, which emerges by applying quantum phenomena to model the complexities and uncertainties inherent in managerial accounting. In contrast, previous works focus more on financial accounting or general accountancy.
- [20] arXiv:2405.00048 [pdf, other]
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Title: Urban planning in a context of rapid urban growth. A large scale review of urban plans in AfricaAuthors: Margherita FaddaComments: Preliminary version. This research was carried out within the scope of my role at the Sahel and West Africa Club. 12 pages. 7 figures. 1 tableSubjects: Physics and Society (physics.soc-ph)
As the African continent continues to urbanise, cities are becoming increasingly central to the transformations of societies and economies. Many studies highlight the limits of urban planning in these cities, emphasising the high share of population living in slums and the low levels of services that reach neighbourhoods. Less attention is given to the urban planning activities that try to prevent or improve these conditions. This analysis of urban plans illustrates that plans are more widespread than commonly thought. They also, for the large part, consider spatial growth. The low number of cities that grew within the projected boundaries of these plans is a symptom of numerous bottlenecks that constrain planning systems in these countries. Examples of these include the disregard of the full built-up areas at the time of the plan's approval and the missing link between the plans and the financial means allocated for its delivery. This article identifies opportunities to overcome these barriers such as flexible and adaptable urban plans that consider the entire built-up area of the agglomeration.
- [21] arXiv:2405.00050 [pdf, other]
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Title: Non-trivial solution to a simple problemAuthors: A.I.MilsteinComments: 6 pages, 2 figuresSubjects: Popular Physics (physics.pop-ph)
The problem of finding the frequencies of small longitudinal oscillations of a spring having a finite mass and stiffness, attached at one end to a wall and at the other end to a body of finite mass, is discussed. This problem was repeatedly proposed at Olympiads for schoolchildren, in various lessons on the Internet, and even on tests in mechanics for students of universities. In all the cases known to me, the implied solution was actually wrong. I discuss two cases: (A) a spring lies on a smooth table, (B) a spring is attached to the ceiling. It is shown that the solution to this simply formulated problem is non-trivial.
- [22] arXiv:2405.00051 [pdf, other]
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Title: Arbitrage impact on the relationship between XRP price and correlation tensor spectra of transaction networksComments: 12 pages, 8 figuresSubjects: Physics and Society (physics.soc-ph); General Finance (q-fin.GN); Statistical Finance (q-fin.ST)
The increasing use of cryptoassets for international remittances has proven to be faster and more cost-effective, particularly for migrants without access to traditional banking. However, the inherent volatility of cryptoasset prices, independent of blockchain-based remittance mechanisms, introduces potential risks during periods of high volatility. This study investigates the intricate dynamics between XRP price fluctuations across diverse crypto exchanges and the correlation of the largest singular values of the correlation tensor of XRP transaction networks. Particularly, we show the impact of arbitrage opportunities across different crypto exchanges on the relationship between XRP price and correlation tensor spectra of transaction networks. Distinct periods, non-bubble and bubble, showcase different characteristics in XRP price fluctuations. Establishing a connection between XRP price and transaction networks, we compute correlation tensors and singular values, emphasizing the significance of the largest singular value. Comparisons with reshuffled and Gaussian random correlation tensors validate the uniqueness of the empirical tensor. A set of simulated weekly XRP prices, resembling arbitrage opportunities across various crypto exchanges, further confirms the robustness of our findings. It reveals a pronounced anti-correlation during bubble periods and a non-significant correlation during non-bubble periods with the largest singular value, irrespective of price fluctuations across different crypto exchanges.
- [23] arXiv:2405.00052 [pdf, ps, other]
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Title: Vortexes as systems specific to the Acoustic WorldComments: 12 pagesSubjects: General Physics (physics.gen-ph)
In this paper we study the properties of vortexes, as systems specific to the Acoustic World, using both hydrodynamic theory and the corresponding hydrodynamic Maxwell equations. According to this study, it follows that the vortex behaves like an acoustic dipole that has intrinsic/internal angular momentum. The system of two identical vortices also has orbital angular momentum and behaves, at distances much greater than the distance between the axes of the vortices, as a single vortex. With the help of Maxwell's hydrodynamic equations for the vortex we deduced the force between two vortices and obtained the expression of the equivalent mass of the vortex and the permittivity of the electroacoustic field. We also obtained and interpreted the expression for the energy density of the acoustic field. The density and pressure variations induced by the vortex cause the change in the propagation speed of the acoustic waves and the acoustic lensing property of the vortex.
- [24] arXiv:2405.00053 [pdf, ps, other]
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Title: A new understanding on the history of developing MRI for cancer detectionAuthors: Donald C. ChangComments: 13 pages, 4 figures, 4 tables; This work was reported in the 2024 APS March Meeting held at Minneapolis as an invited talk given in Session S43: Physics, History, and Future of MRISubjects: Physics and Society (physics.soc-ph); History and Philosophy of Physics (physics.hist-ph)
Science is about facts and truth. Yet sometimes the truth and facts are not obvious. For example, in the field of MRI (Magnetic Resonance Imaging), there has been a long-lasting debate about who were the major contributors in its development. Particularly, there was a strong dispute between the followers of two scientists, R. Damadian and P. Lauterbur. In this review, we carefully trace the major developments in the use of NMR for cancer detection starting almost 50 years ago. The research records show that the truth was beyond the claims of either research camps. The development of NMR for cancer detection involved multiple research groups, who made critical contributions at different junctures.
- [25] arXiv:2405.00054 [pdf, other]
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Title: High-resolution spatio-temporal strain imaging reveals loss mechanisms in a surface acoustic wave deviceAuthors: Tao Zhou, Alexandre Reinhardt, Marie Bousquet, Joel Eymery, Steven Leake, Martin V. Holt, Paul G. Evans, Tobias SchülliSubjects: Applied Physics (physics.app-ph)
Surface acoustic wave devices are key components for processing radio frequency signals in wireless communication because these devices offer simultaneously high performance, compact size and low cost. The optimization of the device structure requires a quantitative understanding of energy conversion and loss mechanisms. Stroboscopic full-field diffraction x-ray microscopy studies of a prototypical one-port resonator device revealed the existence of unanticipated acoustic loss. A non-uniform acoustic excitation in the active area was responsible for the substantial end and side leakages observed at the design frequency. Quantitative analysis of the strain amplitude using a wave decomposition method allowed the determination of several key device parameters. This high-resolution spatiotemporal strain imaging technique is, more generally, suited for studying nanophononics, specifically when the feature size is smaller than optical wavelengths. The strain sensitivity allows precise measurement of acoustic waves with picometer-scale amplitude.
- [26] arXiv:2405.00059 [pdf, other]
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Title: Microwave Cavity Mode Optimisation by Background Anti-Resonance TuningSubjects: Applied Physics (physics.app-ph); Instrumentation and Detectors (physics.ins-det); Optics (physics.optics)
To derive the best oscillator phase noise when implementing a high-Q resonator, the spectral line-shape must have high contrast and symmetry. Ideally, this line-shape is Lorentzian, however, in a high mode density spectral region, low-Q background spurious modes interact and distort the resonance. For a sapphire-loaded cavity resonator operating with whispering gallery modes we show that this high contrast and symmetry can be achieved by changing the dimensions of the surrounding cavity shield to tune the background low-Q structures into anti-resonance. This works because the high-Q resonances are primarily defined by the sapphire while the background modes are defined by the cavity shield. Alternatively, it was shown that a similar result can be achieved by exciting the high-Q resonator with a balanced microwave dipole probe in a Mach Zehnder interferometric configuration. The probe was constructed from two separate coaxial electric field probes symmetrically inserted into a cylindrical cavity resonator, from opposite sides with a small gap between them, so they can behave like an active wire dipole antenna. The power into the two separate probes may be matched with an external variable attenuator in one of the arms of the interferometer. Conversely, the phase between the two electric field probes may be changed with an external variable phase shifter, which changes the nature of the field components the probe couples to. The probe couples to the high-Q resonant modes as well as low-Q background modes, which can be made resonant or anti-resonant for the high-Q modes by changing this external phase. When the background modes are in anti-resonance the line shape of the high-Q mode can be made symmetric and with higher contrast. This technique was applied to both whispering gallery sapphire modes, as well as hollow cavity resonators, without changing the dimensions of the cavity.
- [27] arXiv:2405.00064 [pdf, ps, other]
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Title: Generalized Four-momentum for Continuously Distributed MaterialsAuthors: Sergey G. FedosinComments: 41 pages. Gazi University Journal of Science (2023)Subjects: General Physics (physics.gen-ph)
A four-dimensional differential Euler-Lagrange equation for continuously distributed materials is derived based on the principle of least action, and instead of Lagrangian, this equation contains the Lagrangian density. This makes it possible to determine the density of generalized four-momentum in covariant form as derivative of the Lagrangian density with respect to four-velocity of typical particles of a system taken with opposite sign, and then calculate the generalized four-momentum itself. It is shown that the generalized four-momentum of all typical particles of a system is an integral four-vector and therefore should be considered as a special type of four-vectors. The presented expression for generalized four-momentum exactly corresponds to the Legendre transformation connecting the Lagrangian and Hamiltonian. The obtained formulas are used to calculate generalized four-momentum of stationary and moving relativistic uniform systems for the Lagrangian with particles and vector fields, including electromagnetic and gravitational fields, acceleration field and pressure field. It turns out that the generalized four-momentum of a moving system depends on the total mass of particles, on the Lorentz factor and on the velocity of the systems center of momentum. Besides, an additional contribution is made by the scalar potentials of the acceleration field and the pressure field at the center of system. The direction of the generalized four-momentum coincides with the direction of four-velocity of the system under consideration, while the generalized four-momentum is part of the relativistic four-momentum of the system.
- [28] arXiv:2405.00071 [pdf, ps, other]
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Title: On the Electromagnetic Mass DilemmaComments: 5 pages, 1 figure, and 14 referencesSubjects: General Physics (physics.gen-ph)
We show that a charged sphere moving at a constant velocity $v$ exhibits a mass due to electromagnetic radiation, expressed as $4/(3+(v/c)^2) (E/c^2)$, where $E$ is the electromagnetic energy and $c$ the speed of light in vacuum. Our finding reconciles the longstanding mismatch between the electromagnetic mass calculated from the classical electrodynamics' $4/3 (E/c^2)$ and the relativistic theory.
- [29] arXiv:2405.00079 [pdf, ps, other]
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Title: A global evidence map of human well-being and biodiversity co-benefits and trade-offs of natural climate solutionsAuthors: Charlotte H. Chang, James T. Erbaugh, Paola Fajardo, Luci Lu, István Molnár, Dávid Papp, Brian E. Robinson, Kemen Austin, Susan Cook-Patton, Timm Kroeger, Lindsey Smart, Miguel Castro, Samantha H. Cheng, Peter W. Ellis, Rob I. McDonald, Teevrat Garg, Erin E. Poor, Preston Welker, Andrew R. Tilman, Stephen A. Wood, Yuta J. MasudaComments: 28 pages, 5 figuresSubjects: Physics and Society (physics.soc-ph)
Natural climate solutions (NCS) are critical for mitigating climate change through ecosystem-based carbon removal and emissions reductions. NCS implementation can also generate biodiversity and human well-being co-benefits and trade-offs ("NCS co-impacts"), but the volume of evidence on NCS co-impacts has grown rapidly across disciplines, is poorly understood, and remains to be systematically collated and synthesized. A global evidence map of NCS co-impacts would overcome key barriers to NCS implementation by providing relevant information on co-benefits and trade-offs where carbon mitigation potential alone does not justify NCS projects. We employ large language models to assess over two million articles, finding 257,266 relevant articles on NCS co-impacts. We analyze this large and dispersed body of literature using innovative machine learning methods to extract relevant data (e.g., study location, species, and other key variables), and create a global evidence map on NCS co-impacts. Evidence on NCS co-impacts has grown approximately ten-fold in three decades, although some of the most abundant evidence is associated with pathways that have less mitigation potential. We find that studies often examine multiple NCS pathways, indicating natural NCS pathway complements, and each NCS is often associated with two or more coimpacts. Finally, NCS co-impacts evidence and priority areas for NCS are often mismatched--some countries with high mitigation potential from NCS have few published studies on the broader co-impacts of NCS implementation. Our work advances and makes available novel methods and systematic and representative data of NCS co-impacts studies, thus providing timely insights to inform NCS research and action globally.
- [30] arXiv:2405.00104 [pdf, other]
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Title: Astronomy's climate emissions: Global travel to scientific meetings in 2019Authors: Andrea Gokus, Knud Jahnke, Paul M Woods, Vanessa A Moss, Volker Ossenkopf-Okada, Elena Sacchi, Adam R H Stevens, Leonard Burtscher, Cenk Kayhan, Hannah Dalgleish, Victoria Grinberg, Travis A Rector, Jan Rybizki, Jacob WhiteComments: Supplementary material is available at PNAS Nexus online: this https URLJournal-ref: PNAS Nexus, Volume 3, Issue 5, May 2024, pgae143Subjects: Physics and Society (physics.soc-ph); Instrumentation and Methods for Astrophysics (astro-ph.IM)
Travel to academic conferences -- where international flights are the norm -- is responsible for a sizeable fraction of the greenhouse gas (GHG) emissions associated with academic work. In order to provide a benchmark for comparison with other fields, as well as for future reduction strategies and assessments, we estimate the CO2-equivalent emissions for conference travel in the field of astronomy for the prepandemic year 2019. The GHG emission of the international astronomical community's 362 conferences and schools in 2019 amounted to 42,500 tCO2e, assuming a radiative-forcing index factor of 1.95 for air travel. This equates to an average of 1.0 $\pm$ 0.6 tCO2e per participant per meeting. The total travel distance adds up to roughly 1.5 Astronomical Units, that is, 1.5 times the distance between the Earth and the Sun. We present scenarios for the reduction of this value, for instance with virtual conferencing or hub models, while still prioritizing the benefits conferences bring to the scientific community.
- [31] arXiv:2405.00111 [pdf, other]
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Title: Vorticity Suppression by Particle Lag Effects in Shock-Driven Multiphase InstabilityComments: 36 pages, 16 figuresSubjects: Fluid Dynamics (physics.flu-dyn)
Shock-driven multiphase mixing occurs in many physical systems such as explosive dispersal of chemical or biological agents, in the evolution of supernova remnants, and in supersonic and detonative combustion engines. This mixing process is driven by the Shock Driven Multiphase Instability (SDMI), a derivative of the canonical Richtmyer-Meshkov Instability (RMI). The SDMI deviates from the RMI as particle lag effects become significant, where a higher momentum deficit leads to longer equilibration times and a reduction in hydrodynamic mixing. In this work, the effect of particle lag (rate of momentum transfer) on the SDMI evolution was isolated and investigated utilizing solid nondeforming and nonevaporating particles of differing sizes while holding the effective density ratio (mass of particles in the interface) constant. Three particle sizes were selected with increasing velocity relaxation times. Experiments were conducted by accelerating a cylindrical interface comprised of air and seeded particles surrounded by clean (particle-free) air with a Mach 1.35 shock wave. The development of the multiphase interface was measured using particle imaging velocimetry (PIV). Circulation measurements showed a decrease in mixing with increasing particle size. Finally, a new model, derived from theory, is proposed to predict circulation deposition, mixing energy, in the SDMI based on shock strength, effective density ratio, and particle response times.
- [32] arXiv:2405.00143 [pdf, ps, other]
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Title: Organ Dose Equivalents of Albedo Protons and Neutrons Under Exposure to Large Solar Particle Events during Lunar Human Landing MissionsComments: Pre-print with 25 pagesSubjects: Space Physics (physics.space-ph)
Astronauts participating in lunar landing missions will encounter exposure to albedo particles emitted from the lunar surface as well as primary high-energy particles in the spectra of galactic cosmic rays (GCRs) and solar particle events (SPEs). While existing studies have examined particle energy spectra and absorbed doses in limited radiation exposure scenarios on and near the Moon, comprehensive research encompassing various shielding amounts and large SPEs on the lunar surface remains lacking. Additionally, detailed organ dose equivalents of albedo particles in a human model on the lunar surface have yet to be investigated. This work assesses the organ dose equivalents of albedo neutrons and protons during historically large SPEs in August 1972 and September 1989 utilizing realistic computational anthropomorphic human phantom for the first time. Dosimetric quantities within human organs have been evaluated based on the PHITS Monte Carlo simulation results and quality factors of the state-of-the-art NASA Space Cancer Risk (NSCR) model, as well as ICRP publications. The results with the NSCR model indicate that the albedo contribution to organ dose equivalent is less than 3% for 1 g/cm2 aluminum shielding, while it increases to more than 20% in some organs for 20 g/cm2 aluminum shielding during exposure to low-energy-proton-rich SPEs.
- [33] arXiv:2405.00150 [pdf, other]
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Title: An Invertible All-optical Logic Gate on ChipSubjects: Optics (physics.optics); Quantum Physics (quant-ph)
We demonstrate an invertible all-optical gate on chip, with the roles of control and signal switchable by slightly adjusting their relative arrival time at the gate. It is based on quantum Zeno blockade driven by sum-frequency generation in a periodic-poled lithium niobate microring resonator. For two nearly-identical nanosecond pulses, the later arriving pulse is modulated by the earlier arriving one, resulting in 2.4 and 3.9 power extinction between the two, respectively, when their peak power is 1 mW and 2 mW. Our results, while to be improved and enriched, herald a new paradigm of logical gates and circuits for exotic applications.
- [34] arXiv:2405.00193 [pdf, other]
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Title: Thawed Gaussian wavepacket dynamics with $Δ$-machine learned potentialsComments: 12 pages, 3 figuresSubjects: Chemical Physics (physics.chem-ph); Quantum Physics (quant-ph)
A method for performing variable-width (thawed) Gaussian wavepacket (GWP) variational dynamics on machine-learned potentials is presented. Instead of fitting the potential energy surface (PES), the anharmonic correction to the global harmonic approximation (GHA) is fitted using kernel ridge regression -- this is a $\Delta$-machine learning approach. The training set consists of energy differences between ab initio electronic energies and values given by the GHA. The learned potential is subsequently used to propagate a single thawed GWP using the time-dependent variational principle to compute the autocorrelation function, which provides direct access to vibronic spectra via its Fourier transform. We applied the developed method to simulate the photoelectron spectrum of ammonia and found excellent agreement between theoretical and experimental spectra. We show that fitting the anharmonic corrections requires a smaller training set as compared to fitting total electronic energies. We also demonstrate that our approach allows to reduce the dimensionality of the nuclear space used to scan the PES when constructing the training set. Thus, only the degrees of freedom associated with large amplitude motions need to be treated with $\Delta$-machine learning, which paves a way for reliable simulations of vibronic spectra of large floppy molecules.
- [35] arXiv:2405.00203 [pdf, ps, other]
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Title: A simple truth hidden in plain sight: All molecules are entangled according to chemical common senseAuthors: Jing KongSubjects: Chemical Physics (physics.chem-ph)
An equation that determines the numbers of electrons for molecules is proposed based on chemical common sense. It shows that all molecules are entangled in number of electrons and results in the fundamental assumption of molecular energy convexity that underpins molecular quantum mechanics. It also leads to the concept of fractional numbers of electrons for molecules in a statistical sense. The energy of a molecule is piecewise linear with respect to its continuous number of electrons. Wavefunction interpretation of this equation of nature shows that an individual molecule with noninteger number of electrons is locally physical, whereas a molecule with integer number of electrons is locally real. The complete theoretical proof of the equation is still to be had.
- [36] arXiv:2405.00211 [pdf, other]
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Title: Healing Gradient Degradation in Nb3Sn SRF Cavities Using a Recoating MethodSubjects: Accelerator Physics (physics.acc-ph)
Despite having advantageous superconducting properties, Nb3Sn superconducting radiofrequency (SRF) cavities still have practical challenges compared to Nb SRF cavities due to the brittle nature of Nb3Sn. Performance degradation can occur when a Nb3Sn SRF cavity experiences mechanical stresses such as during handling and tuning of the cavity. In this study, we present a potential treatment for SRF cavities that have experienced stress induced performance degradation that involves a recoating procedure. The degraded cavity is coated with a small amount of Sn using a single step vapor-diffusion methodology. Using this approach we can recover a significant portion of the lost performance of a Nb3Sn SRF cavity.
- [37] arXiv:2405.00241 [pdf, ps, other]
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Title: Fast MRI Reconstruction Using Deep Learning-based Compressed Sensing: A Systematic ReviewSubjects: Medical Physics (physics.med-ph)
Magnetic resonance imaging (MRI) has revolutionized medical imaging, providing a non-invasive and highly detailed look into the human body. However, the long acquisition times of MRI present challenges, causing patient discomfort, motion artifacts, and limiting real-time applications. To address these challenges, researchers are exploring various techniques to reduce acquisition time and improve the overall efficiency of MRI. One such technique is compressed sensing (CS), which reduces data acquisition by leveraging image sparsity in transformed spaces. In recent years, deep learning (DL) has been integrated with CS-MRI, leading to a new framework that has seen remarkable growth. DL-based CS-MRI approaches are proving to be highly effective in accelerating MR imaging without compromising image quality. This review comprehensively examines DL-based CS-MRI techniques, focusing on their role in increasing MR imaging speed. We provide a detailed analysis of each category of DL-based CS-MRI including end-to-end, unroll optimization, self-supervised, and federated learning. Our systematic review highlights significant contributions and underscores the exciting potential of DL in CS-MRI. Additionally, our systematic review efficiently summarizes key results and trends in DL-based CS-MRI including quantitative metrics, the dataset used, acceleration factors, and the progress of and research interest in DL techniques over time. Finally, we discuss potential future directions and the importance of DL-based CS-MRI in the advancement of medical imaging. To facilitate further research in this area, we provide a GitHub repository that includes up-to-date DL-based CS-MRI publications and publicly available datasets - https://github.com/mosaf/Awesome-DL-based-CS-MRI.
- [38] arXiv:2405.00245 [pdf, other]
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Title: Flexible multi-bunch-length operation for continuous-wave x-ray free-electron lasersSubjects: Accelerator Physics (physics.acc-ph)
The X-ray free-electron lasers (XFELs) are cutting-edge instruments pivotal in a broad range of fields, providing high-power X-ray pulses with durations spanning from femtoseconds to attoseconds. One of the critical challenges in XFEL facilities is the simultaneous accommodation of diverse requirements for XFEL operation modes and photon properties across different undulator lines. This paper proposes a dipole-kicker combination in the bunch compressors to vary the electron bunch length for the continuous-wave XFEL facilities driven by a superconducting linac. This method enables optimization of the electron bunch length on a per-bunch basis, tailored to each specific needs of each undulator. Through start-to-end simulations based on the parameters of the Shanghai high-repetition-rate XFEL and extreme light facility, we demonstrate the feasibility of this technique. The results show its effectiveness in enabling simultaneous operations of self-amplified spontaneous emission and externally seeded FEL across different undulator lines, ensuring optimal electron bunch compression for each undulator line.
- [39] arXiv:2405.00259 [pdf, ps, other]
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Title: Optimization of Dark-Field CT for Lung ImagingSubjects: Medical Physics (physics.med-ph); Image and Video Processing (eess.IV)
Background: X-ray grating-based dark-field imaging can sense the small angle scattering caused by an object's micro-structure. This technique is sensitive to lung's porous alveoli and is able to detect lung disease at an early stage. Up to now, a human-scale dark-field CT has been built for lung imaging. Purpose: This study aimed to develop a more thorough optimization method for dark-field lung CT and summarize principles for system design. Methods: We proposed a metric in the form of contrast-to-noise ratio (CNR) for system parameter optimization, and designed a phantom with concentric circle shape to fit the task of lung disease detection. Finally, we developed the calculation method of the CNR metric, and analyzed the relation between CNR and system parameters. Results: We showed that with other parameters held constant, the CNR first increases and then decreases with the system auto-correlation length (ACL). The optimal ACL is nearly not influenced by system's visibility, and is only related to phantom's property, i.e., scattering material's size and phantom's absorption. For our phantom, the optimal ACL is about 0.21 {\mu}m. As for system geometry, larger source-detector and isocenter-detector distance can increase the system's maximal ACL, helping the system meet the optimal ACL more easily. Conclusions: This study proposed a more reasonable metric and a task-based process for optimization, and demonstrated that the system optimal ACL is only related to the phantom's property.
- [40] arXiv:2405.00279 [pdf, other]
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Title: Beyond a Richardson-Gaudin mean-field: Slater-Condon rules and perturbation theoryAuthors: Paul A. JohnsonSubjects: Chemical Physics (physics.chem-ph); Strongly Correlated Electrons (cond-mat.str-el)
Richardson-Gaudin states provide a basis of the Hilbert space for strongly correlated electrons. In this study, optimal expressions for the transition density matrix elements between Richardson-Gaudin states are obtained with a cost comparable with the corresponding reduced density matrix elements. Analogues of the Slater-Condon rules are identified based on the number of near-zero singular values of the RG state overlap matrix. Finally, a perturbative approach is shown to be close in quality to a configuration interaction of Richardson-Gaudin states while being feasible to compute.
- [41] arXiv:2405.00284 [pdf, other]
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Title: Sub-terahertz optomechanicsSubjects: Optics (physics.optics); Applied Physics (physics.app-ph)
We demonstrate optomechanics in the sub-terahertz regime. An optical racetrack resonator, patterned from thin-film lithium niobate, is suspended to support mechanical structures oscillating at these extremely high frequencies, which are read out through cavity optomechanical coupling. Our hybrid platform paves the way for advancing mechanical systems in the quantum regime at elevated temperatures.
- [42] arXiv:2405.00286 [pdf, ps, other]
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Title: Ultrafast Photocurrent Hysteresis in Photoferroelectric α-In2Se3Subjects: Optics (physics.optics)
The photon-electron interactions are generally volatile and the intricate multiphysics details of photoexcited carrier dynamics are not yet distinguished. How to nonvolatile control the physical state through all-optical means and clarify the intricate physical processes has been a long-term goal pursued in polar materials. Photoferroelectric {\alpha}-In2Se3 holds the great potential for capturing multimodal nonvolatile states due to the spontaneous reversible in-plane and out-of-plane polarizations and its tunable light-matter interactions arising from the electronic degree of freedom. Here we uncover a nonvolatile zero-bias ultrafast photocurrent hysteresis response with an all-optical scheme, diagnosed by in-plane and out-of-plane terahertz waves emitted from the photoferroelectric {\alpha}-In2Se3. The mechanism of such ultrafast photocurrent hysteresis emerges as a result of anomalous bulk linear and circular photovoltaic effect synchronously driven by local polarization rearrangement. Utilizing anisotropic ferroelectric kinetics-induced relative phase between the in-plane and out-of-plane directions, we further show flexibly selective chirality, tunable rotational angle, and optimizable ellipticity of terahertz wave polarizations. Our finding offers a promising avenue towards direct ultrafast nonvolatile processing of photocurrent signals through an all-optical scheme.
- [43] arXiv:2405.00288 [pdf, other]
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Title: Intrinsic phase based proper orthogonal decomposition (IPhaB POD): a method for physically interpretable modes in near-periodic systemsSubjects: Fluid Dynamics (physics.flu-dyn)
Fluid dynamics systems driven by dominant, nearly periodic large-scale dynamics are common across wakes, jets, rotating machinery, and high-speed flows. Traditional decomposition techniques such as proper orthogonal decomposition and dynamic mode decomposition have been used to gain insight into these flows, but can require many modes to represent physical processes. With the aim of generating modes that intuitively convey the underlying physical mechanisms, we propose an intrinsic phase-based proper orthogonal decomposition (IPhaB POD) method. IPhaB POD creates energetically ranked modes that evolve along a characteristic cycle of a driving near-periodic large scale. Our proposed formulation is set in the time domain, which is particularly useful in cases where the large-scale dynamics are imperfectly periodic. We formally derive IPhaB POD within a proper orthogonal decomposition framework, and it inherits the optimal representation inherent to POD. As part of this derivation, a dynamical systems representation of the large scale is utilized, facilitating a definition of phase relative to the large scale within the time domain. An expectation operator and inner product are also constructed relative to this definition of phase in a manner that allows for the various cycles within the data to demonstrate imperfect periodicity. The formulation is tested on two sample problems: a simple, low Reynolds number airfoil wake, and a complex, high-speed pulsating shock wave problem. The resulting modes are shown to better isolate the large-scale dynamics in the first mode than space-only proper orthogonal decomposition, and to highlight meaningful small-scale dynamics in higher modes for the shock flow problem.
- [44] arXiv:2405.00339 [pdf, ps, other]
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Title: Canonized then Minimized RMSD for Three-Dimensional StructuresSubjects: Chemical Physics (physics.chem-ph)
Existing molecular canonization algorithms typically operate on one-dimensional (1D) string representations or two-dimensional (2D) connectivity graphs of a molecule and are not able to differentiate equivalent atoms based on three-dimensional (3D) structures. The stereochemical tags on each atom are in fact determined according to established Cahn-Ingold-Prelog (CIP) rules for comparing grades, which can help to further differentiate atoms with similar environment. Therefore, a stereochemical-rule-based canonization algorithm that is capable of assigning canonical indices using 3D structural information is of great value. On top of the Schneider-Sayle-Landrum (SSL) partition-based canonization algorithm, we propose an enhanced canonization algorithm to expand its applicability. The initial index assignment rules are redesigned, so that the obtained canonical indices are compatible with the most of the common CIP Sequence Rules, which greatly eases the stereochemical assignment. Furthermore, a branching tiebreaking step is added to secure an accurate evaluation of the structural difference through the minimized root-mean-square deviation (RMSD) between structures, with an option to include hydrogen atoms or not. Our algorithm is implemented with Python and can efficiently obtain minimized RMSD taking into account of the symmetry of molecular systems , contributing to the fields of drug design, molecular docking, and data analysis of molecular dynamics simulation.
- [45] arXiv:2405.00343 [pdf, other]
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Title: From Compton Scattering of photons on targets to Inverse Compton Scattering of electron and photon beamsSubjects: Accelerator Physics (physics.acc-ph)
We revisit the kinematics of Compton Scattering (electron-photon interactions producing electrons and photons in the exit channel) covering the full range of energy/momenta distribution between the two colliding particles, with a dedicated view to statistical properties of secondary beams that are generated in beam-beam collisions. Starting from the Thomson inverse scattering, where electrons do not recoil and photons are back-scattered to higher energies by a Lorentz boost effect (factor $4\gamma^2$), we analyze three transition points, separating four regions. These are in sequence, given by increasing the electron recoil (numbers are for transition points, letters for regions): a) Thomson back-scattering, 1) equal sharing of total energy in the exit channel between electron and photon, b) deep recoil regime where the bandwidth/energy spread of the two interacting beams are exchanged in the exit channel, 2) electron is stopped, i.e. taken down at rest in the laboratory system by colliding with an incident photon of $mc^2/2$ energy, c) electron back-scattering region, where incident electron is back-scattered by the incident photon, 3) symmetric scattering, when the incident particles carry equal and opposite momenta, so that in the exit channel they are back-scattered with same energy/momenta, d) Compton scattering ($a'$ $la$ Arthur Compton, see ref.4), where photons carry an energy much larger than the colliding electron energy. For each region and/or transition point we discuss the potential effects of interest in diverse areas, like generating mono-chromatic gamma ray beams in deep recoil regions with spectral purification, or possible mechanisms of generation and propagation of very high energy photons in the cosmological domain.
- [46] arXiv:2405.00430 [pdf, ps, other]
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Title: Continuous sPatial-Temporal Deformable Image Registration (CPT-DIR) for motion modelling in radiotherapy: beyond classic voxel-based methodsSubjects: Medical Physics (physics.med-ph); Computer Vision and Pattern Recognition (cs.CV)
Background and purpose: Deformable image registration (DIR) is a crucial tool in radiotherapy for extracting and modelling organ motion. However, when significant changes and sliding boundaries are present, it faces compromised accuracy and uncertainty, determining the subsequential contour propagation and dose accumulation procedures. Materials and methods: We propose an implicit neural representation (INR)-based approach modelling motion continuously in both space and time, named Continues-sPatial-Temporal DIR (CPT-DIR). This method uses a multilayer perception (MLP) network to map 3D coordinate (x,y,z) to its corresponding velocity vector (vx,vy,vz). The displacement vectors (dx,dy,dz) are then calculated by integrating velocity vectors over time. The MLP's parameters can rapidly adapt to new cases without pre-training, enhancing optimisation. The DIR's performance was tested on the DIR-Lab dataset of 10 lung 4DCT cases, using metrics of landmark accuracy (TRE), contour conformity (Dice) and image similarity (MAE). Results: The proposed CPT-DIR can reduce landmark TRE from 2.79mm to 0.99mm, outperforming B-splines' results for all cases. The MAE of the whole-body region improves from 35.46HU to 28.99HU. Furthermore, CPT-DIR surpasses B-splines for accuracy in the sliding boundary region, lowering MAE and increasing Dice coefficients for the ribcage from 65.65HU and 90.41% to 42.04HU and 90.56%, versus 75.40HU and 89.30% without registration. Meanwhile, CPT-DIR offers significant speed advantages, completing in under 15 seconds compared to a few minutes with the conventional B-splines method. Conclusion: Leveraging the continuous representations, the CPT-DIR method significantly enhances registration accuracy, automation and speed, outperforming traditional B-splines in landmark and contour precision, particularly in the challenging areas.
- [47] arXiv:2405.00432 [pdf, other]
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Title: Dynamic Mueller matrix polarimetry using generalized measurementsAuthors: Amy McWilliam, Mustafa A. Al Khafaji, Sphinx J. Svensson, Sebastião Pádua, Sonja Franke-ArnoldSubjects: Optics (physics.optics)
Mueller matrices provide a complete description of a medium's response to excitation by polarized light, and their characterization is important across a broad range of applications from ellipsometry in material science to polarimetry in biochemistry, medicine and astronomy. Here we introduce single-shot Mueller matrix polarimetry based on generalized measurements performed with a Poincar\'e beam. We determine the Mueller matrix of a homogeneous medium with unknown optical activity by detecting its optical response to a Poincar\'e beam, which across its profile contains all polarization states, and analyze the resulting polarization pattern in terms of four generalized measurements, which are implemented as a path-displaced Sagnac interferometer. We illustrate the working of our Mueller matrix polarimetry on the example of tilted and rotated wave plates and find excellent agreement with predictions as well as alternative Stokes measurements. After initial calibration, the alignment of the device stays stable for up to 8 hours, promising suitability for the dynamic characterization of Mueller matrices that change in time.
- [48] arXiv:2405.00455 [pdf, ps, other]
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Title: The Maxwell evolution equation of electromagnetic resonators: a mathematical proof with explicit derivationSubjects: Optics (physics.optics); Mathematical Physics (math-ph)
In a recent publication [1], the authors employ electromagnetic quasinormal-mode theory to establish an "exact" Maxwell evolution (EME) equation governing resonator dynamics. This resulting equation bears resemblance to the classical evolution equation proposed heuristically in the temporal coupled-mode theory (CMT), yet it also presents differences. One significant difference is that the driving force in the EME equation is proportional to the derivative of the incident field, whereas in the CMT evolution equation, it is proportional to the incident field itself. This unexpected finding was substantiated by a numerical test and a mathematical demonstration in [1]. The test remains undisputed in this study. However, the demonstration unfortunately relies on unjustified shortcuts. We promptly highlight these shortcuts while proposing an alternative demonstration that is direct and indisputable. The new demonstration provides a firm mathematical foundation for the EME equation and reinforces its credibility.
- [49] arXiv:2405.00478 [pdf, ps, other]
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Title: Dual-frequency optical-microwave atomic clocks based on cesium atomsAuthors: Tiantian Shi, Qiang Wei, Xiaomin Qin, Zhenfeng Liu, Kunkun Chen, Shiying Cao, Hangbo Shi, Zijie Liu, Jingbiao ChenComments: 8 pages, 4 figuresSubjects: Atomic Physics (physics.atom-ph); Optics (physics.optics); Quantum Physics (quant-ph)
$^{133}$Cs, which is the only stable cesium (Cs) isotope, is one of the most investigated elements in atomic spectroscopy and was used to realize the atomic clock in 1955. Among all atomic clocks, the cesium atomic clock has a special place, since the current unit of time is based on a microwave transition in the Cs atom. In addition, the long lifetime of the $6{\text{P}}_{3/2}$ state and simple preparation technique of Cs vapor cells have great relevance to quantum and atom optics experiments, which suggests the use of the $6{\text{S}} - 6{\text{P}}$ D2 transition as an optical frequency standard. In this work, using one laser as the local oscillator and Cs atoms as the quantum reference, we realized two atomic clocks in the optical and microwave frequencies, respectively. Both clocks could be freely switched or simultaneously output. The optical clock based on the vapor cell continuously operated with a frequency stability of $3.89 \times {10^{ - 13}}$ at 1 s, decreasing to $2.17 \times {10^{ - 13}}$ at 32 s, which was frequency stabilized by modulation transfer spectroscopy and estimated by an optical comb. Then, applying this stabilized laser for an optically pumped Cs beam atomic clock to reduce the laser frequency noise, we obtained a microwave clock with a frequency stability of $1.84 \times {10^{ - 12}}/\sqrt \tau $, reaching $5.99 \times {10^{ - 15}}$ at $10^5$ s. This study demonstrates an attractive feature for the commercialization and deployment of optical and microwave clocks and will guide further development of integrated atomic clocks with better stability. Thus, this study lays the groundwork for future quantum metrology and laser physics.
- [50] arXiv:2405.00484 [pdf, ps, other]
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Title: Spin Hamiltonians in the Modulated Momenta of LightComments: 18 pages, 5 figuresSubjects: Optics (physics.optics); Statistical Mechanics (cond-mat.stat-mech); Quantum Physics (quant-ph)
Photonic solvers that are able to find the ground states of different spin Hamiltonians can be used to study many interactive physical systems and combinatorial optimization problems. Here, we establish a real-and-momentum space correspondence of spin Hamiltonians by spatial light transport. The real-space spin interaction is determined by modulating the momentum-space flow of light. This principle is formulated as a generalized Plancherel theorem, allowing us to implement a simple optical simulator that can find the ground states for any displacement-dependent spin interactions. Particularly, we use this principle to reveal the exotic magnetic phase diagram from a J1-J2-J3 model, and we also observe the vortex-mediated Berezinskii-Kosterlitz-Thouless dynamics from the XY model. These experiments exhibit high calculation precision by subtly controlling spin interactions from the momentum space of light, offering a promising scheme to explore novel physical effects.
- [51] arXiv:2405.00506 [pdf, ps, other]
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Title: Significant tuning of internal mode coupling in doubly clamped MEMS beam resonators by thermal effectSubjects: Applied Physics (physics.app-ph)
Intermodal coupling has been demonstrated to be a promising mechanism for the development of advanced micro/nanoelectromechanical devices. However, strong mode coupling remains a key challenge limiting the practical application of intermodal coupling. Furthermore, the insight into physical mechanisms underlying mode coupling and the capability to quantitatively tune the mode coupling is also limited. Here, we experimentally and theoretically demonstrate the significant tunability of mode coupling by using the thermal tuning effect, yet in an asymmetric doubly-clamped MEMS beam resonator, enabling various coupling strength to be implemented for practical applications. In this system, two out-of-plane vibrational modes are mechanically coupled through displacement-induced tension, and their mode coupling strength arises from both hardening and softening nonlinearities of the two modes, thus allowing for the tuning of mode coupling strength by thermally enhancing the softening nonlinearity of the MEMS beam. Our results demonstrate a feasible approach to tune the mode coupling and offer insights into fundamental mechanism of mode coupling in MEMS beam resonators, paving the way for the development of MEMS resonators with enhanced performance and application-specific tunability.
- [52] arXiv:2405.00512 [pdf, other]
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Title: Quantum rates in dissipative systems with spatially varying frictionAuthors: Oliver Bridge, Paolo Lazzaroni, Rocco Martinazzo, Mariana Rossi, Stuart C. Althorpe, Yair LitmanSubjects: Chemical Physics (physics.chem-ph)
We investigate whether making the friction spatially dependent introduces quantum effects into the thermal reaction rates for dissipative reactions. We calculate the quantum rates using the numerically exact multi-configuration time-dependent Hartree (MCTDH) method, as well as the approximate ring-polymer molecular dynamics (RPMD), ring-polymer instanton (RPI) methods, and classical mechanics. By conducting simulations across a wide range of temperatures and friction strengths, we can identify the various regimes that govern the reactive dynamics. At high temperatures, in addition to the spatial-diffusion and energy-diffusion regimes predicted by Kramer's rate theory, a (coherent) tunnelling-dominated regime is identified at low friction. At low temperatures, incoherent tunnelling dominates most of Kramer's curve, except at very low friction when coherent tunnelling becomes dominant. Unlike in classical mechanics, the bath's influence changes the equilibrium time-independent properties of the system, leading to a complex interplay between spatially dependent friction and nuclear quantum effects even at high temperatures. More specifically, we show that a realistic friction profile can lead to an increase (decrease) of the quantum (classical) rates with friction within the spatial-diffusion regime, showing that classical and quantum rates display qualitatively different behaviours. Except at very low frictions, we find that RPMD captures most of the quantum effects in the thermal reaction rates.
- [53] arXiv:2405.00521 [pdf, other]
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Title: Temperature dependence of Coherent versus spontaneous Raman ScatteringAuthors: Giovanni Batignani, Emanuele Mai, Miles Martinati, Mohanan M. Neethish, Shaul Mukamel, Tullio ScopignoSubjects: Optics (physics.optics); Chemical Physics (physics.chem-ph)
Due to their sub picosecond temporal resolution, coherent Raman spectroscopies have been proposed as a viable extension of Spontaneous Raman (SR) thermometry, to determine dynamics of mode specific vibrational energy content during out of equilibrium molecular processes. Here we show that the presence of multiple laser fields stimulating the vibrational coherences introduces additional quantum pathways, resulting in destructive interference. This ultimately reduces the thermal sensitivity of single spectral lines, nullifying it for harmonic vibrations and temperature independent polarizability. We demonstrate how harnessing anharmonic signatures such as vibrational hot bands enables coherent Raman thermometry.
- [54] arXiv:2405.00547 [pdf, other]
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Title: Transport of topological defects in a biphasic mixture of active and passive nematic fluidsAuthors: KVS Chaithanya, Aleksandra Ardaševa, Oliver J. Meacock, William M. Durham, Sumesh P. Thampi, Amin DoostmohammadiSubjects: Biological Physics (physics.bio-ph); Soft Condensed Matter (cond-mat.soft)
Collectively moving cellular systems often contain a proportion of dead cells or non-motile genotypes. When mixed, nematically aligning motile and non-motile agents are known to segregate spontaneously. However, the role that topological defects and active stresses play in shaping the distribution of the two phases remains unresolved. In this study, we investigate the behaviour of a two-dimensional binary mixture of active and passive nematic fluids to understand how topological defects are transported between the two phases and, ultimately, how this leads to the segregation of topological charges. When the activity of the motile phase is large, and the tension at the interface of motile and non-motile phases is weak, we find that the active phase tends to accumulate $+1/2$ defects and expel $-1/2$ defects so that the motile phase develops a net positive charge. Conversely, when the activity of the motile phase is comparatively small and interfacial tension is strong, the opposite occurs so that the active phase develops a net negative charge. We then use these simulations to develop a physical intuition of the underlying processes that drive the charge segregation. Lastly, we quantify the sensitivity of this process on the other model parameters, by exploring the effect that anchoring strength, orientational elasticity, friction, and volume fraction of the motile phase have on topological charge segregation. As $+1/2$ and $-1/2$ defects have very different effects on interface morphology and fluid transport, this study offers new insights into the spontaneous pattern formation that occurs when motile and non-motile cells interact.
- [55] arXiv:2405.00563 [pdf, other]
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Title: Physics-Informed Acoustic Liner Optimization: Balancing Drag and NoiseSubjects: Fluid Dynamics (physics.flu-dyn)
We present pore-resolved Direct Numerical Simulations (DNS) of turbulent flows grazing over acoustic liners with aerodynamically and/or acoustically optimized orifice configurations. Our DNS explore a large parameter space, studying various families of orifice geometries, including the influence of orifice shape, orientation, and the number of orifices. All flow cases show an increase in drag compared to the smooth wall. However, the added drag can be reduced by as much as $\sim$55\% as compared to conventional acoustic liners by simply altering the shape of the orifice or its orientation, in the case of a non-circular orifice. Complementary acoustic simulations demonstrate that this reduced drag may be achieved while maintaining the same noise reduction properties over a wide range of frequencies.
- [56] arXiv:2405.00591 [pdf, other]
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Title: The origin of wall-shear stress fluctuations in wall-bounded turbulenceSubjects: Fluid Dynamics (physics.flu-dyn)
The origin of wall shear-stress fluctuations in wall turbulence was studied through energy dissipation at the wall. While confirming the universality in wall dissipation at small inner scales, the dissipation at larger scales is a consequence of near-wall scale interactions. In particular, the energy transport from the universal small to larger scale strengthens with Reynolds number due to the growing number of intermediate scales associated with the log layer. We anticipate that these insights broadly apply to all canonical wall-bounded turbulence for sufficiently high Reynolds numbers.
- [57] arXiv:2405.00636 [pdf, other]
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Title: Robustness of graph embedding methods for community detectionComments: 17 pages, 26 figures, 3 tables. Comments are welcomeSubjects: Physics and Society (physics.soc-ph); Machine Learning (cs.LG); Social and Information Networks (cs.SI); Data Analysis, Statistics and Probability (physics.data-an)
This study investigates the robustness of graph embedding methods for community detection in the face of network perturbations, specifically edge deletions. Graph embedding techniques, which represent nodes as low-dimensional vectors, are widely used for various graph machine learning tasks due to their ability to capture structural properties of networks effectively. However, the impact of perturbations on the performance of these methods remains relatively understudied. The research considers state-of-the-art graph embedding methods from two families: matrix factorization (e.g., LE, LLE, HOPE, M-NMF) and random walk-based (e.g., DeepWalk, LINE, node2vec). Through experiments conducted on both synthetic and real-world networks, the study reveals varying degrees of robustness within each family of graph embedding methods. The robustness is found to be influenced by factors such as network size, initial community partition strength, and the type of perturbation. Notably, node2vec and LLE consistently demonstrate higher robustness for community detection across different scenarios, including networks with degree and community size heterogeneity. These findings highlight the importance of selecting an appropriate graph embedding method based on the specific characteristics of the network and the task at hand, particularly in scenarios where robustness to perturbations is crucial.
- [58] arXiv:2405.00640 [pdf, other]
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Title: Stochastic fluids with transport noise: Approximating diffusion from data using SVD and ensemble forecast back-propagationAuthors: James WoodfieldSubjects: Fluid Dynamics (physics.flu-dyn); Computational Physics (physics.comp-ph)
We introduce and test methods for the calibration of the diffusion term in Stochastic Partial Differential Equations (SPDEs) describing fluids. We take two approaches, one uses ideas from the singular value decomposition and the Biot-Savart law. The other backpropagates through an ensemble forecast, with respect to diffusion parameters, to minimise a probabilistic ensemble forecasting metric. We describe the approaches in the specific context of solutions to SPDEs describing the evolution of fluid particles, sometimes called inviscid vortex methods. The methods are tested in an idealised setting in which the reference data is a known realisation of the parameterised SPDE, and also using a forecast verification metric known as the Continuous Rank Probability Score (CRPS).
- [59] arXiv:2405.00647 [pdf, other]
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Title: Screening of BindingDB database ligands against EGFR, HER2, Estrogen, Progesterone and NF-kB receptors based on machine learning and molecular dockingSubjects: Medical Physics (physics.med-ph); Machine Learning (cs.LG)
Breast cancer, the second most prevalent cancer among women worldwide, necessitates the exploration of novel therapeutic approaches. To target the four subgroups of breast cancer "hormone receptor-positive and HER2-negative, hormone receptor-positive and HER2-positive, hormone receptor-negative and HER2-positive, and hormone receptor-negative and HER2-negative" it is crucial to inhibit specific targets such as EGFR, HER2, ER, NF-kB, and PR.
In this study, we evaluated various methods for binary and multiclass classification. Among them, the GA-SVM-SVM:GA-SVM-SVM model was selected with an accuracy of 0.74, an F1-score of 0.73, and an AUC of 0.94 for virtual screening of ligands from the BindingDB database. This model successfully identified 4454, 803, 438, and 378 ligands with over 90% precision in both active/inactive and target prediction for the classes of EGFR+HER2, ER, NF-kB, and PR, respectively, from the BindingDB database. Based on to the selected ligands, we created a dendrogram that categorizes different ligands based on their targets. This dendrogram aims to facilitate the exploration of chemical space for various therapeutic targets.
Ligands that surpassed a 90% threshold in the product of activity probability and correct target selection probability were chosen for further investigation using molecular docking. The binding energy range for these ligands against their respective targets was calculated to be between -15 and -5 kcal/mol. Finally, based on general and common rules in medicinal chemistry, we selected 2, 3, 3, and 8 new ligands with high priority for further studies in the EGFR+HER2, ER, NF-kB, and PR classes, respectively. - [60] arXiv:2405.00649 [pdf, other]
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Title: Electronic Coherences in Molecules: The Projected Nuclear Quantum Momentum as a Hidden AgentSubjects: Chemical Physics (physics.chem-ph)
Electronic coherences are key to understanding and controlling photo-induced molecular transformations. We identify a crucial quantum-mechanical feature of electron-nuclear correlation, the projected nuclear quantum momenta, essential to capture the correct coherence behavior. In simulations, we show that, unlike traditional trajectory-based schemes, exact-factorization-based methods approximate these correlation terms, and correctly capture electronic coherences in a range of situations, including their spatial dependence, an important aspect that influences subsequent electron dynamics and that is becoming accessible in more experiments.
Cross-lists for Thu, 2 May 24
- [61] arXiv:2405.00018 (cross-list from cs.DC) [pdf, other]
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Title: Proof-of-concept: Using ChatGPT to Translate and Modernize an Earth System Model from Fortran to Python/JAXSubjects: Distributed, Parallel, and Cluster Computing (cs.DC); Atmospheric and Oceanic Physics (physics.ao-ph)
Earth system models (ESMs) are vital for understanding past, present, and future climate, but they suffer from legacy technical infrastructure. ESMs are primarily implemented in Fortran, a language that poses a high barrier of entry for early career scientists and lacks a GPU runtime, which has become essential for continued advancement as GPU power increases and CPU scaling slows. Fortran also lacks differentiability - the capacity to differentiate through numerical code - which enables hybrid models that integrate machine learning methods. Converting an ESM from Fortran to Python/JAX could resolve these issues. This work presents a semi-automated method for translating individual model components from Fortran to Python/JAX using a large language model (GPT-4). By translating the photosynthesis model from the Community Earth System Model (CESM), we demonstrate that the Python/JAX version results in up to 100x faster runtimes using GPU parallelization, and enables parameter estimation via automatic differentiation. The Python code is also easy to read and run and could be used by instructors in the classroom. This work illustrates a path towards the ultimate goal of making climate models fast, inclusive, and differentiable.
- [62] arXiv:2405.00057 (cross-list from cond-mat.mtrl-sci) [pdf, other]
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Title: Microstructural and Transport Characteristics of Triply Periodic Bicontinuous MaterialsComments: 16 pages, 6 figures, and 5 tablesSubjects: Materials Science (cond-mat.mtrl-sci); Applied Physics (physics.app-ph)
3D bicontinuous two-phase materials are increasingly gaining interest because of their unique multifunctional characteristics and advancements in techniques to fabricate them. Due to their complex topological and structural properties, it still has been nontrivial to develop explicit microstructure-dependent formulas to predict accurately their physical properties. A primary goal of the present paper is to ascertain various microstructural and transport characteristics of five different models of triply periodic bicontinuous porous materials at a porosity $\phi_1=1/2$: those in which the two-phase interfaces are the Schwarz P, Schwarz D and Schoen G minimal surfaces as well as two different pore-channel structures. We ascertain their spectral densities, pore-size distribution functions, local volume-fraction variances, and hyperuniformity order metrics and then use this information to estimate certain effective transport properties via closed-form microstructure-property formulas. Specifically, we estimate the recently introduced time-dependent diffusion spreadability exactly from the spectral density. Moreover, we accurately estimate the fluid permeability of such porous materials from the second moment of the pore-size function and the formation factor, a measure of the tortuosity of the pore space. We also rigorously bound the permeability from above using the spectral density. For the five models with identical cubic unit cells, we find that the permeability, inverse of the specific surface, hyperuniformity order metric, pore-size second moment and long-time spreadability behavior are all positively correlated and rank order the structures in exactly the same way. We also conjecture what structures maximize the fluid permeability for arbitrary porosities and show that this conjecture must be true in the extreme porosity limits by identifying the corresponding optimal structures.
- [63] arXiv:2405.00151 (cross-list from hep-ph) [pdf, other]
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Title: An analytical formula for signal optimization in stimulated photon-photon scattering setup with three laser pulsesComments: 14 pages, 9 figuresSubjects: High Energy Physics - Phenomenology (hep-ph); Optics (physics.optics)
We consider a setup to detect stimulated photon-photon scattering using high-power lasers. Signal photons are emitted from an overlap of the incoming intense laser pulses focused in vacuum from three sides. We derive and justify a general approximate analytical formula for the angular distribution and total yield of such signal photons in terms of the parameters of the incoming pulses, including their intensity, carrier frequencies, durations, focusing, polarizations, mutual orientation and overlap. Using the obtained formula a parametric study of the signal is carried out and optimization is performed.
- [64] arXiv:2405.00174 (cross-list from astro-ph.SR) [pdf, other]
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Title: Using sunRunner3D to interpret the global structure of the heliosphere from in situ measurementsComments: 31 pages, 9 figures, 3 tables, accepted for publication in the Journal of Space Weather and Space ClimateSubjects: Solar and Stellar Astrophysics (astro-ph.SR); Space Physics (physics.space-ph)
Understanding the large-scale three-dimensional structure of the inner heliosphere, while important in its own right, is crucial for space weather applications, such as forecasting the time of arrival and propagation of coronal mass ejections (CMEs). This study uses sunRunner3D (3D), a 3-D magnetohydrodynamic (MHD) model, to simulate solar wind (SW) streams and generate background states. SR3D employs the boundary conditions generated by CORona-HELiosphere (CORHEL) and the PLUTO code to compute the plasma properties of the SW with the MHD approximation up to 1.1 AU in the inner heliosphere. We demonstrate that SR3D reproduces global features of Corotating Interaction Regions (CIRs) observed by Earth-based spacecraft (OMNI) and the Solar TErrestial RElations Observatory (STEREO)-A for a set of Carrington rotations (CRs) that cover a period that lays in the late declining phase of solar cycle 24. Additionally, we demonstrate that the model solutions are valid in the corotating and inertial frames of references. Moreover, a comparison between SR3D simulations and in-situ measurements shows reasonable agreement with the observations, and our results are comparable to those achieved by Predictive Science Inc.'s Magnetohydrodynamic Algorithm outside a Sphere (MAS) code. We have also undertaken a comparative analysis with the Space Weather Adaptive Simulation Framework for Solar Wind (SWASTi-SW), a PLUTO physics-based model, to evaluate the precision of various initial boundary conditions. Finally, we discuss the disparities in the solutions derived from inertial and rotating frames.
- [65] arXiv:2405.00190 (cross-list from quant-ph) [pdf, other]
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Title: Distribution of lowest eigenvalue in $k$-body bosonic random matrix ensemblesComments: 18 pages, 9 figuresSubjects: Quantum Physics (quant-ph); Data Analysis, Statistics and Probability (physics.data-an); Applications (stat.AP)
We numerically study the distribution of the lowest eigenvalue of finite many-boson systems with $k$-body interactions modeled by Bosonic Embedded Gaussian Orthogonal [BEGOE($k$)] and Unitary [BEGUE($k$)] random matrix Ensembles. Following the recently established result that the $q$-normal describes the smooth form of the eigenvalue density of the $k$-body embedded ensembles, the first four moments of the distribution of lowest eigenvalues have been analyzed as a function of the $q$ parameter, with $q \sim 1$ for $k = 1$ and $q = 0$ for $k = m$; $m$ being the number of bosons. Our results show the distribution exhibits a smooth transition from Gaussian like for $q$ close to 1 to a modified Gumbel like for intermediate values of $q$ to the well-known Tracy-Widom distribution for $q=0$.
- [66] arXiv:2405.00299 (cross-list from cond-mat.mtrl-sci) [pdf, ps, other]
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Title: Thermal stability and phase transformation of $α$-, $κ(ε)$-, and $γ$-Ga$_2$O$_3$ thin films to $β$-Ga$_2$O$_3$ under various ambient conditionsComments: 15 pages, 6 figures, 1 tableSubjects: Materials Science (cond-mat.mtrl-sci); Applied Physics (physics.app-ph)
Phase transitions in metastable $\alpha$-, $\kappa(\epsilon)$-, and $\gamma$-Ga$_2$O$_3$ films to thermodynamically stable $\beta$-Ga$_2$O$_3$ during annealing in air, N$_2$, and vacuum have been systematically investigated via in-situ high-temperature X-ray diffraction and scanning electron microscopy. These respective polymorphs exhibited thermal stability to around 471-525$^\circ$C, 773-825$^\circ$C, and 490-575$^\circ$C before transforming into $\beta$-Ga$_2$O$_3$, across all tested ambient conditions. Particular crystallographic orientation relationships were observed before and after the phase transitions, i.e., (0006) $\alpha$-Ga$_2$O$_3$ $\parallel$ $(\overline{4}02)$ $\beta$-Ga$_2$O$_3$, (004) $\kappa(\epsilon)$-Ga$_2$O$_3$ $\parallel$ (310) and $(\overline{4}02)$ $\beta$-Ga$_2$O$_3$, and (400) $\gamma$-Ga$_2$O$_3$ $\parallel$ (400) $\beta$-Ga$_2$O$_3$. The phase transition of $\alpha$-Ga$_2$O$_3$ to $\beta$-Ga$_2$O$_3$ resulted in catastrophic damage to the film and upheaval of the surface. The respective primary and possibly secondary causes of this damage are the +8.6% volume expansion and the dual displacive and reconstructive transformations that occur during this transition. The $\kappa(\epsilon)$- and $\gamma$-Ga$_2$O$_3$ films converted to $\beta$-Ga$_2$O$_3$ via singular reconstructive transformations with small changes in volume and unchanged surface microstructures.
- [67] arXiv:2405.00317 (cross-list from math.DS) [pdf, other]
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Title: Input gradient annealing neural network for solving low-temperature Fokker-Planck equationsSubjects: Dynamical Systems (math.DS); Computational Physics (physics.comp-ph)
We present a novel yet simple deep learning approach, called input gradient annealing neural network (IGANN), for solving stationary Fokker-Planck equations. Traditional methods, such as finite difference and finite elements, suffer from the curse of dimensionality. Neural network based algorithms are meshless methods, which can avoid the curse of dimensionality. However, at low temperature, when directly solving a stationary Fokker-Planck equation with more than two metastable states in the generalized potential landscape, the small eigenvalue introduces numerical difficulties due to a large condition number. To overcome these problems, we introduce the IGANN method, which uses a penalty of negative input gradient annealing during the training. We demonstrate that the IGANN method can effectively solve high-dimensional and low-temperature Fokker-Planck equations through our numerical experiments.
- [68] arXiv:2405.00336 (cross-list from astro-ph.SR) [pdf, ps, other]
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Title: Comparison of Ion-Proton Differential Speed between ICMEs and Solar Wind near 1 auAuthors: Xuechao Zhang, Hongqiang Song, Chengxiao Zhang, Hui Fu, Leping Li, Jinrong Li, Xiaoqian Wang, Rui Wang, Yao ChenComments: 14 pages, 8 figuresSubjects: Solar and Stellar Astrophysics (astro-ph.SR); Space Physics (physics.space-ph)
The elemental abundance of ICMEs and solar wind near 1 au is often adopted to represent the abundance in the corresponding coronal sources. However, the absolute abundance of heavy ions (relative to hydrogen) near 1 au might be different from the coronal abundance due to the ion-proton differential speed ($V_{ip}$). To illustrate the $V_{ip}$ characteristics and explore whether it influences the absolute abundance analysis for ICMEs and solar wind, we perform a statistical study on the $V_{ip}$ for He$^{2+}$, C$^{5+}$, O$^{6+}$, and Fe$^{10+}$ in both ICMEs and solar wind based on measurements of Advanced Composition Explorer. The results show that the $V_{ip}$ is negligible within ICMEs and slow solar wind ($<$ 400 km s$^{-1}$), while obvious in the intermediate (400 -- 600 km s$^{-1}$) and fast wind ($>$ 600 km s$^{-1}$). Previous studies showed that the $V_{ip}$ in ICMEs keeps negligible during propagation from 0.3 to 5 au, but in solar wind it increases with the decreasing heliocentric distance. Therefore, it might be questionable to infer the absolute abundance of coronal sources through in-situ abundance near 1 au for solar wind. Fortunately, the ion-oxygen (O$^{6+}$) differential speed ($V_{io}$) is negligible for He$^{2+}$, C$^{5+}$, and Fe$^{10+}$ within both ICMEs and solar wind, and previous studies suggested that the $V_{io}$ does not vary significantly with the heliocentric distance. This indicates that various heavy ions always flow at the same bulk speed and their relative abundance (relative to oxygen) near 1 au can represent the coronal abundance for both ICMEs and solar wind.
- [69] arXiv:2405.00400 (cross-list from quant-ph) [pdf, other]
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Title: A Dual Open Atom Interferometer for Compact, Mobile Quantum SensingAuthors: Yosri Ben-Aïcha, Zain Mehdi, Christian Freier, Stuart S. Szigeti, Paul B. Wigley, Lorcán O. Conlon, Ryan Husband, Samuel Legge, Rhys H. Eagle, Joseph J. Hope, Nicholas P. Robins, John D. Close, Kyle S. Hardman, Simon A. Haine, Ryan J. ThomasSubjects: Quantum Physics (quant-ph); Atomic Physics (physics.atom-ph)
We demonstrate an atom interferometer measurement protocol compatible with operation on a dynamic platform. Our method employs two open interferometers, derived from the same atomic source, with different interrogation times to eliminate initial velocity dependence while retaining precision, accuracy, and long term stability. We validate the protocol by measuring gravitational tides, achieving a precision of 4.5 {\mu}Gal in 2000 runs, marking the first demonstration of inertial quantity measurement with open atom interferometry that achieves long-term phase stability.
- [70] arXiv:2405.00405 (cross-list from quant-ph) [pdf, other]
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Title: Pure State Inspired Lossless Post-selected Quantum Metrology of Mixed StatesAuthors: Jing YangComments: 7 pages, 2 figuresSubjects: Quantum Physics (quant-ph); Optics (physics.optics)
Given an ensemble of identical pure quantum states that depend on an unknown parameter, recently it was shown that the quantum Fisher information can be losslessly compressed into a subensemble with a much smaller number of samples. However, generalization to mixed states leads to a technical challenge that is formidable to overcome directly. In this work, we avoid such technicality by unveiling the physics of a featured lossless post-selection measurement: while the post-selected quantum state is unchanged, the parametric derivative of the density operator is amplified by a large factor equal to the square root of the inverse of the post-selection success probability. This observation not only clarifies the intuition and essence of post-selected quantum metrology but also allows us to develop a mathematically compact theory for the lossless post-selection of mixed states. We find that if the parametric derivative of the density operator of a mixed state, or alternatively the symmetric logarithmic derivative, vanishes on the support of the density matrix, lossless post-selection can be achieved with an arbitrarily large amplification factor. We exemplify with the examples of superresolution imaging and unitary encoding of mixed initial states. Our results are useful for realistic post-selected quantum metrology in the presence of decoherence and of foundational interests to several problems in quantum information theory.
- [71] arXiv:2405.00425 (cross-list from cond-mat.str-el) [pdf, other]
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Title: Quantum Monte Carlo study of the phase diagram of the two-dimensional uniform electron liquidSubjects: Strongly Correlated Electrons (cond-mat.str-el); Plasma Physics (physics.plasm-ph); Quantum Physics (quant-ph)
We present a study of spin-unpolarized and spin-polarized two-dimensional uniform electron liquids using variational and diffusion quantum Monte Carlo (VMC and DMC) methods with Slater-Jastrow-backflow trial wave functions. Ground-state VMC and DMC energies are obtained in the density range $1 \leq r_\text{s} \leq 40$. Single-particle and many-body finite-size errors are corrected using canonical-ensemble twist-averaged boundary conditions and extrapolation of twist-averaged energies to the thermodynamic limit of infinite system size. System-size-dependent errors in Slater-Jastrow-backflow DMC energies caused by partially converged VMC energy minimization calculations are discussed. We find that, for $1 \leq r_\text{s} \leq 5$, optimizing the backflow function at each twist lowers the twist-averaged DMC energy at finite system size. However, nonsystematic system-size-dependent effects remain in the DMC energies, which can be partially removed by extrapolation from multiple finite system sizes to infinite system size. We attribute these nonsystematic effects to the close competition between fluid and defected crystal phases at different system sizes at low density. The DMC energies in the thermodynamic limit are used to parameterize a local spin density approximation correlation functional for inhomogeneous electron systems. Our zero-temperature phase diagram shows a single transition from a paramagnetic fluid to a hexagonal Wigner crystal at $r_\text{s}=35(1)$, with no region of stability for a ferromagnetic fluid.
- [72] arXiv:2405.00459 (cross-list from cs.SI) [pdf, other]
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Title: U.S. Election Hardens Hate UniverseSubjects: Social and Information Networks (cs.SI); Human-Computer Interaction (cs.HC); Adaptation and Self-Organizing Systems (nlin.AO); Physics and Society (physics.soc-ph)
Local or national politics can trigger potentially dangerous hate in someone. But with a third of the world's population eligible to vote in elections in 2024 alone, we lack understanding of how individual-level hate multiplies up to hate behavior at the collective global scale. Here we show, based on the most recent U.S. election, that offline events are associated with a rapid adaptation of the global online hate universe that hardens (strengthens) both its network-of-networks structure and the 'flavors' of hate content that it collectively produces. Approximately 50 million potential voters in hate communities are drawn closer to each other and to the broad mainstream of approximately 2 billion others. It triggers new hate content at scale around immigration, ethnicity, and antisemitism that aligns with conspiracy theories about Jewish-led replacement before blending in hate around gender identity/sexual orientation, and religion. Telegram acts as a key hardening agent - yet is overlooked by U.S. Congressional hearings and new E.U. legislation. Because the hate universe has remained robust since 2020, anti-hate messaging surrounding not only upcoming elections but also other events like the war in Gaza, should pivot to blending multiple hate 'flavors' while targeting previously untouched social media structures.
- [73] arXiv:2405.00462 (cross-list from astro-ph.HE) [pdf, other]
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Title: Saturation Level of Ion Weibel Instability and Isotropization Length Scale in Electron-Ion Weibel-Mediated ShocksComments: Accepted for publication in MNRAS. 11 pages, 15 figuresSubjects: High Energy Astrophysical Phenomena (astro-ph.HE); Plasma Physics (physics.plasm-ph)
Ion Weibel instability is considered to be the dominant physics for the dissipation in high-Mach number astrophysical shocks such as supernova remnant shocks and gamma-ray burst shocks. We study the instability dependence on various parameters using theory and particle-in-cell simulations. We demonstrate that electron physics determines the saturation level of the Weibel-generated magnetic field, even though the instability is driven by the ions. We discuss the application to astrophysical and laboratory laser experiment environments to clarify the roles of the ion Weibel instability. We develop a model for the isotropization length scale in Weibel-mediated shocks and compare its value to other characteristic length scales of each system. We find that electron heating to near equipartition is crucial for the formation of ultra-relativistic Weibel-mediated shocks. On the other hand, our results imply that non-relativistic shocks in typical interstellar medium are not purely mediated by the Weibel instability.
- [74] arXiv:2405.00517 (cross-list from cond-mat.mtrl-sci) [pdf, ps, other]
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Title: Contrasting Irradiation Behavior of Dual Phases in Ti-6Al-4V Alloy at Low-Temperature Due to Omega-phase Precursors in Beta-phase MatrixComments: 36 pages, 15 figuresSubjects: Materials Science (cond-mat.mtrl-sci); Accelerator Physics (physics.acc-ph)
Aiming to simulate the radiation damage effect on a dual alpha+beta phase Ti-6Al-4V alloy utilized as high-intensity accelerator beam window material, a series of irradiation experiments were conducted with a 2.8 MeV-Fe^2+ ion beam in several dpa regions at room temperature. The nano-indentation hardness increased steeply at 1 dpa and unchanged up to 10 dpa, due to the saturation of defect clusters and tangled dislocations in the dominant alpha-phase matrix with a size of 2~3 nm and a density of about 1x10^23 m^-3. In contrast in the intergranular beta-phase, larger loops of 20~30 nm diameter were observed with much less density of about 5x10^20 m^-3. The diffraction pattern showed rectilinear diffuse streaks between the beta-phase reflections, corresponding to the omega-phase precursor, without dose dependency in its intensity. FFT/I-FFT analysis of the HREM revealed a sub-nanometer-sized lattice disorder with local fluctuations, not discrete but continuous, and homogeneously distributed within the matrix beta-phase stably against the irradiation. The significantly low dislocation density and the absence of phase transformation in the beta-phase matrix could be attributed either to the strong sink effect expected for this distinctive sub-nanometer-sized homogeneous lattice disorder or to the anomalous point defect recombination induced by the high mobility of vacancies, both of which are originated from the metastable omega-phase precursors specifically formed in the beta(BCC) phase of group-4 transition metals.
- [75] arXiv:2405.00540 (cross-list from cs.CY) [pdf, other]
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Title: Heat, Health, and Habitats: Analyzing the Intersecting Risks of Climate and Demographic Shifts in Austrian DistrictsSubjects: Computers and Society (cs.CY); General Economics (econ.GN); Atmospheric and Oceanic Physics (physics.ao-ph)
The impact of hot weather on health outcomes of a population is mediated by a variety of factors, including its age profile and local green infrastructure. The combination of warming due to climate change and demographic aging suggests that heat-related health outcomes will deteriorate in the coming decades. Here, we measure the relationship between weekly all-cause mortality and heat days in Austrian districts using a panel dataset covering $2015-2022$. An additional day reaching $30$ degrees is associated with a $2.4\%$ increase in mortality per $1000$ inhabitants during summer. This association is roughly doubled in districts with a two standard deviation above average share of the population over $65$. Using forecasts of hot days (RCP) and demographics in $2050$, we observe that districts will have elderly populations and hot days $2-5$ standard deviations above the current mean in just $25$ years. This predicts a drastic increase in heat-related mortality. At the same time, district green scores, measured using $10\times 10$ meter resolution satellite images of residential areas, significantly moderate the relationship between heat and mortality. Thus, although local policies likely cannot reverse warming or demographic trends, they can take measures to mediate the health consequences of these growing risks, which are highly heterogeneous across regions, even in Austria.
- [76] arXiv:2405.00541 (cross-list from q-bio.PE) [pdf, other]
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Title: New Trends on the Systems Approach to Modeling SARS-CoV-2 Pandemics in a Globally Connected PlanetAuthors: Giulia Bertaglia, Andrea Bondesan, Diletta Burini, Raluca Eftimie, Lorenzo Pareschi, Giuseppe ToscanSubjects: Populations and Evolution (q-bio.PE); Adaptation and Self-Organizing Systems (nlin.AO); Physics and Society (physics.soc-ph)
This paper presents a critical analysis of the literature and perspective research ideas for modeling the epidemics caused by the SARS-CoV-2 virus. It goes beyond deterministic population dynamics to consider several key complexity features of the system under consideration. In particular, the multiscale features of the dynamics from contagion to the subsequent dynamics of competition between the immune system and the proliferating virus. Other topics addressed in this work include the propagation of epidemics in a territory, taking into account local transportation networks, the heterogeneity of the population, and the study of social and economic problems in populations involved in the spread of epidemics. The overall content aims to show how new mathematical tools can be developed to address the above topics and how mathematical models and simulations can contribute to the decision making of crisis managers.
- [77] arXiv:2405.00590 (cross-list from cond-mat.soft) [pdf, other]
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Title: Nonlinear Poisson effect in affine semiflexible polymer networksSubjects: Soft Condensed Matter (cond-mat.soft); Statistical Mechanics (cond-mat.stat-mech); Biological Physics (physics.bio-ph)
Stretching an elastic material along one axis typically induces contraction along the transverse axes, a phenomenon known as the Poisson effect. From these strains, one can compute the specific volume, which generally either increases or, in the incompressible limit, remains constant as the material is stretched. However, in networks of semiflexible or stiff polymers, which are typically highly compressible yet stiffen significantly when stretched, one instead sees a significant reduction in specific volume under finite strains. This volume reduction is accompanied by increasing alignment of filaments along the strain axis and a nonlinear elastic response, with stiffening of the apparent Young's modulus. For semiflexible networks, in which entropic bending elasticity governs the linear elastic regime, the nonlinear Poisson effect is caused by the nonlinear force-extension relationship of the constituent filaments, which produces a highly asymmetric response of the constituent polymers to stretching and compression. The details of this relationship depend on the geometric and elastic properties of the underlying filaments, which can vary greatly in experimental systems. Here, we provide a comprehensive characterization of the nonlinear Poisson effect in an affine network model and explore the influence of filament properties on essential features of the macroscopic response, including strain-driven alignment and volume reduction.
- [78] arXiv:2405.00598 (cross-list from eess.SP) [pdf, ps, other]
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Title: Pseudo-noise pulse-compression thermography: a powerful tool for time-domain thermography analysisComments: 24 paged, 20 figuresSubjects: Signal Processing (eess.SP); Applied Physics (physics.app-ph)
Pulse-compression is a correlation-based measurement technique successfully used in many NDE applications to increase the SNR in the presence of huge noise, strong signal attenuation or when high excitation levels must be avoided. In thermography, the pulse-compression approach was firstly introduced in 2005 by Mulavesaala and co-workers, and then further developed by Mandelis and co-authors that applied to thermography the concept of the thermal-wave radar developed for photothermal measurements. Since then, many measurement schemes and applications have been reported in the literature by several groups by using various heating sources, coded excitation signals, and processing algorithms. The variety of such techniques is known as pulse-compression thermography or thermal-wave radar imaging. Even despite the continuous improvement of these techniques during these years, the advantages of using a correlation-based approach in thermography are still not fully exploited and recognized by the community. This is because up to now the reconstructed thermograms' time sequences after pulse-compression were affected by the so-called sidelobes. This is a severe drawback since it hampers an easy interpretation of the data and their comparison with other thermography techniques. To overcome this issue and unleash the full potential of the approach, this paper shows how it is possible to implement a pulse-compression thermography procedure capable of suppressing any sidelobe by using a pseudo-noise excitation and a proper processing algorithm.
- [79] arXiv:2405.00645 (cross-list from cs.LG) [pdf, other]
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Title: Gradient-based Automatic Per-Weight Mixed Precision Quantization for Neural Networks On-ChipSubjects: Machine Learning (cs.LG); Instrumentation and Detectors (physics.ins-det)
Model size and inference speed at deployment time, are major challenges in many deep learning applications. A promising strategy to overcome these challenges is quantization. However, a straightforward uniform quantization to very low precision can result in significant accuracy loss. Mixed-precision quantization, based on the idea that certain parts of the network can accommodate lower precision without compromising performance compared to other parts, offers a potential solution. In this work, we present High Granularity Quantization (HGQ), an innovative quantization-aware training method designed to fine-tune the per-weight and per-activation precision in an automatic way for ultra-low latency and low power neural networks which are to be deployed on FPGAs. We demonstrate that HGQ can outperform existing methods by a substantial margin, achieving resource reduction by up to a factor of 20 and latency improvement by a factor of 5 while preserving accuracy.
- [80] arXiv:2405.00661 (cross-list from gr-qc) [pdf, other]
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Title: Towards quantum gravity with neural networks: Solving quantum Hamilton constraints of 3d Euclidean gravity in the weak coupling limitComments: 46 pages, 14 figuresSubjects: General Relativity and Quantum Cosmology (gr-qc); High Energy Physics - Theory (hep-th); Computational Physics (physics.comp-ph)
We consider 3-dimensional Euclidean gravity in the weak coupling limit of Smolin and show that it is BF-theory with $\text{U(1)}^3$ as a Lie group. The theory is quantised using loop quantum gravity methods. The kinematical degrees of freedom are truncated, on account of computational feasibility, by fixing a graph and deforming the algebra of the holonomies to impose a cutoff on the charge vectors. This leads to a quantum theory related to $\text{U}_q \text{(1)}^3$ BF-theory. The effect of imposing the cutoff on the charges is examined. We also implement the quantum volume operator of 3d loop quantum gravity. Most importantly we compare two constraints for the quantum model obtained: a master constraint enforcing curvature and Gauss constraint, as well as a combination of a quantum Hamilton constraint constructed using Thiemann's strategy and the Gauss master constraint. The two constraints are solved using the neural network quantum state ansatz, demonstrating its ability to explore models which are out of reach for exact numerical methods. The solutions spaces are quantitatively compared and although the forms of the constraints are radically different, the solutions turn out to have a surprisingly large overlap. We also investigate the behavior of the quantum volume in solutions to the constraints.
- [81] arXiv:2405.00663 (cross-list from quant-ph) [pdf, other]
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Title: Quantum cryptographic protocols with dual messaging system via 2D alternate quantum walks and genuine single particle entangled statesComments: 11 pages (including supplementary material), 2 figures and 1 tableSubjects: Quantum Physics (quant-ph); Disordered Systems and Neural Networks (cond-mat.dis-nn); Cryptography and Security (cs.CR); Quantum Algebra (math.QA); Optics (physics.optics)
Single-particle entangled states (SPES) can offer a more secure way of encoding and processing quantum information than their multi-particle counterparts. The SPES generated via a 2D alternate quantum-walk setup from initially separable states can be either 3-way or 2-way entangled. This letter shows that the generated genuine three-way and nonlocal two-way SPES can be used as cryptographic keys to securely encode two distinct messages simultaneously. We detail the message encryption-decryption steps and show the resilience of the 3-way and 2-way SPES-based cryptographic protocols against eavesdropper attacks like intercept-and-resend and man-in-the-middle. We also detail how these protocols can be experimentally realized using single photons, with the three degrees of freedom being OAM, path, and polarization. These have unparalleled security for quantum communication tasks. The ability to simultaneously encode two distinct messages using the generated SPES showcases the versatility and efficiency of the proposed cryptographic protocol. This capability could significantly improve the throughput of quantum communication systems.
- [82] arXiv:2405.00669 (cross-list from astro-ph.CO) [pdf, other]
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Title: Euclid preparation. LensMC, weak lensing cosmic shear measurement with forward modelling and Markov Chain Monte Carlo samplingAuthors: Euclid Collaboration: G. Congedo (1), L. Miller (2), A. N. Taylor (1), N. Cross (1), C. A. J. Duncan (3 and 2), T. Kitching (4), N. Martinet (5), S. Matthew (1), T. Schrabback (6), M. Tewes (7), N. Welikala (1), N. Aghanim (8), A. Amara (9), S. Andreon (10), N. Auricchio (11), M. Baldi (12 and 11 and 13), S. Bardelli (11), R. Bender (14 and 15), C. Bodendorf (14), D. Bonino (16), E. Branchini (17 and 18 and 10), M. Brescia (19 and 20 and 21), J. Brinchmann (22), S. Camera (23 and 24 and 16), V. Capobianco (16), C. Carbone (25), V. F. Cardone (26 and 27), J. Carretero (28 and 29), S. Casas (30), F. J. Castander (31 and 32), M. Castellano (26), S. Cavuoti (20 and 21), A. Cimatti (33), C. J. Conselice (3), L. Conversi (34 and 35), Y. Copin (36), F. Courbin (37), H. M. Courtois (38), M. Cropper (4), et al. (202 additional authors not shown)Comments: 28 pages, 18 figures, 2 tablesSubjects: Cosmology and Nongalactic Astrophysics (astro-ph.CO); Data Analysis, Statistics and Probability (physics.data-an); Computation (stat.CO)
LensMC is a weak lensing shear measurement method developed for Euclid and Stage-IV surveys. It is based on forward modelling to deal with convolution by a point spread function with comparable size to many galaxies; sampling the posterior distribution of galaxy parameters via Markov Chain Monte Carlo; and marginalisation over nuisance parameters for each of the 1.5 billion galaxies observed by Euclid. The scientific performance is quantified through high-fidelity images based on the Euclid Flagship simulations and emulation of the Euclid VIS images; realistic clustering with a mean surface number density of 250 arcmin$^{-2}$ ($I_{\rm E}<29.5$) for galaxies, and 6 arcmin$^{-2}$ ($I_{\rm E}<26$) for stars; and a diffraction-limited chromatic point spread function with a full width at half maximum of $0.^{\!\prime\prime}2$ and spatial variation across the field of view. Objects are measured with a density of 90 arcmin$^{-2}$ ($I_{\rm E}<26.5$) in 4500 deg$^2$. The total shear bias is broken down into measurement (our main focus here) and selection effects (which will be addressed elsewhere). We find: measurement multiplicative and additive biases of $m_1=(-3.6\pm0.2)\times10^{-3}$, $m_2=(-4.3\pm0.2)\times10^{-3}$, $c_1=(-1.78\pm0.03)\times10^{-4}$, $c_2=(0.09\pm0.03)\times10^{-4}$; a large detection bias with a multiplicative component of $1.2\times10^{-2}$ and an additive component of $-3\times10^{-4}$; and a measurement PSF leakage of $\alpha_1=(-9\pm3)\times10^{-4}$ and $\alpha_2=(2\pm3)\times10^{-4}$. When model bias is suppressed, the obtained measurement biases are close to Euclid requirement and largely dominated by undetected faint galaxies ($-5\times10^{-3}$). Although significant, model bias will be straightforward to calibrate given the weak sensitivity.
Replacements for Thu, 2 May 24
- [83] arXiv:2208.02014 (replaced) [pdf, ps, other]
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Title: Myasthenia Gravis Diagnosis with Surface-enhanced Raman SpectroscopySubjects: Medical Physics (physics.med-ph); Optics (physics.optics)
- [84] arXiv:2212.11743 (replaced) [pdf, other]
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Title: Amoeba Formulation of Non-Bloch Band Theory in Arbitrary DimensionsComments: 21 pages, 11 figures, 1 tableJournal-ref: Physical Review X 14, 021011 (2024)Subjects: Mesoscale and Nanoscale Physics (cond-mat.mes-hall); Quantum Gases (cond-mat.quant-gas); Mathematical Physics (math-ph); Optics (physics.optics); Quantum Physics (quant-ph)
- [85] arXiv:2301.10097 (replaced) [pdf, other]
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Title: Canonical variables based numerical schemes for hybrid plasma models with kinetic ions and massless electronsComments: 25 pages, 8 figuresSubjects: Numerical Analysis (math.NA); Plasma Physics (physics.plasm-ph)
- [86] arXiv:2305.07679 (replaced) [pdf, other]
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Title: Version 2.0.0 -- SPARC: Simulation Package for Ab-initio Real-space CalculationsAuthors: Boqin Zhang, Xin Jing, Qimen Xu, Shashikant Kumar, Abhiraj Sharma, Lucas Erlandson, Sushree Jagriti Sahoo, Edmond Chow, Andrew J. Medford, John E. Pask, Phanish SuryanarayanaComments: 13 pages, 2 figuresSubjects: Computational Physics (physics.comp-ph); Materials Science (cond-mat.mtrl-sci)
- [87] arXiv:2305.17108 (replaced) [pdf, other]
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Title: Selective social interactions and speed-induced leadership in schooling fishAuthors: Andreu Puy, Elisabet Gimeno, Jordi Torrents, Palina Bartashevich, M. Carmen Miguel, Romualdo Pastor-Satorras, Pawel RomanczukComments: Main paper (14 pages) + Supplementary Information (18 pages)Journal-ref: Proceedings of the National Academy of Sciences 121 (18), e2309733121 (2024)Subjects: Biological Physics (physics.bio-ph)
- [88] arXiv:2306.05960 (replaced) [pdf, other]
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Title: Acoustic resolvent analysis of turbulent jetsComments: Accepted for publication in TCFDSubjects: Fluid Dynamics (physics.flu-dyn)
- [89] arXiv:2306.15481 (replaced) [pdf, other]
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Title: Zeitlin truncation of a Shallow Water Quasi-Geostrophic model for planetary flowComments: Second version, 19 pages, 5 figures, accepted at JAMESSubjects: Fluid Dynamics (physics.flu-dyn)
- [90] arXiv:2307.00489 (replaced) [pdf, other]
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Title: Theoretical Limits of Energy Extraction in Active FluidsComments: 8+7 pages, 8 figuresSubjects: Soft Condensed Matter (cond-mat.soft); Other Condensed Matter (cond-mat.other); Statistical Mechanics (cond-mat.stat-mech); Fluid Dynamics (physics.flu-dyn)
- [91] arXiv:2307.02091 (replaced) [pdf, ps, other]
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Title: Quantum support vector machines for classification and regression on a trapped-ion quantum computerComments: 31 pages, 8 figures, 3 tables, 2 supplementary figures, 3 supplementary tablesSubjects: Quantum Physics (quant-ph); Chemical Physics (physics.chem-ph)
- [92] arXiv:2307.10182 (replaced) [pdf, other]
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Title: Enhancing Super-Resolution Networks through Realistic Thick-Slice CT SimulationComments: 11 pages, 4 figuresSubjects: Image and Video Processing (eess.IV); Artificial Intelligence (cs.AI); Computer Vision and Pattern Recognition (cs.CV); Medical Physics (physics.med-ph)
- [93] arXiv:2308.05806 (replaced) [pdf, other]
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Title: Gain-compensated metal cavity modes and a million-fold improvement of Purcell factorsJournal-ref: Optica Quantum 2, 85-90 (2024)Subjects: Optics (physics.optics); Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
- [94] arXiv:2308.13096 (replaced) [pdf, other]
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Title: Electronic Structure Prediction of Multi-million Atom Systems Through Uncertainty Quantification Enabled Transfer LearningAuthors: Shashank Pathrudkar, Ponkrshnan Thiagarajan, Shivang Agarwal, Amartya S. Banerjee, Susanta GhoshSubjects: Materials Science (cond-mat.mtrl-sci); Disordered Systems and Neural Networks (cond-mat.dis-nn); Computational Physics (physics.comp-ph); Quantum Physics (quant-ph)
- [95] arXiv:2310.13485 (replaced) [pdf, other]
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Title: Towards nanophotonic optical isolation via inverse design of energy transfer in non-reciprocal mediaSubjects: Optics (physics.optics); Quantum Physics (quant-ph)
- [96] arXiv:2310.18352 (replaced) [pdf, other]
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Title: Theory of Rayleigh-Brillouin optical activity light scattering applicable to chiral liquidsSubjects: Optics (physics.optics); Soft Condensed Matter (cond-mat.soft)
- [97] arXiv:2310.20489 (replaced) [pdf, other]
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Title: Northward Propagating Versus Non-propagating BSISO over South Asia: Horizontal Advection Driven Moisture Mode Within a Vertically Sheared BackgroundComments: 36 pages, 14 figures. Submitted to JGR:AtmospheresSubjects: Atmospheric and Oceanic Physics (physics.ao-ph)
- [98] arXiv:2311.03012 (replaced) [pdf, other]
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Title: The role of viscosity on drop impact forcesComments: version after first round of the reviewSubjects: Fluid Dynamics (physics.flu-dyn); Soft Condensed Matter (cond-mat.soft)
- [99] arXiv:2312.11114 (replaced) [pdf, other]
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Title: 3D surface profilometry using neutral helium atomsComments: 7 pages (including bibliography), 5 figures (including Appendix). Accepted at Applied Physics Letters on 19th April 2024Subjects: Atomic Physics (physics.atom-ph); Applied Physics (physics.app-ph); Instrumentation and Detectors (physics.ins-det)
- [100] arXiv:2312.15796 (replaced) [pdf, other]
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Title: GenCast: Diffusion-based ensemble forecasting for medium-range weatherAuthors: Ilan Price, Alvaro Sanchez-Gonzalez, Ferran Alet, Tom R. Andersson, Andrew El-Kadi, Dominic Masters, Timo Ewalds, Jacklynn Stott, Shakir Mohamed, Peter Battaglia, Remi Lam, Matthew WillsonComments: Main text 11 pages, Appendices 76 pagesSubjects: Machine Learning (cs.LG); Atmospheric and Oceanic Physics (physics.ao-ph)
- [101] arXiv:2401.01347 (replaced) [pdf, ps, other]
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Title: Convex Regions of Opinion Dynamics, Approaches to the Complexity of Binary Consensus with Reference to Addiction and Obliviousness: Integrated Dimer Model PerspectiveAuthors: Yasuko KawahataComments: Discussion Paper: Theory of opinion distribution in human relations where trust and distrust mixed(2020)Subjects: Physics and Society (physics.soc-ph)
- [102] arXiv:2401.04529 (replaced) [pdf, ps, other]
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Title: Comment on Infrared dielectric function of Ga(As,P) semiconductor alloys near the reststrahlen bands (Applied Physics Letters 123, 172102, 2023)Comments: 23 pages, 6 figuresSubjects: Materials Science (cond-mat.mtrl-sci); Applied Physics (physics.app-ph)
- [103] arXiv:2401.16544 (replaced) [pdf, other]
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Title: Stochastic Distinguishability of Markovian TrajectoriesSubjects: Statistical Mechanics (cond-mat.stat-mech); Biological Physics (physics.bio-ph); Quantitative Methods (q-bio.QM)
- [104] arXiv:2402.07378 (replaced) [pdf, other]
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Title: Combination of crystal growth with optical floating zone and evaluation of Nd3+:LaAlO3 crystals with the dynamic nuclear polarization of 139La and 27AlAuthors: Kohei Ishizaki, Ikuo Ide, Masaki Fujita, Hiroki Hotta, Yuki Ito, Masataka Iinuma, Yoichi Ikeda, Takahiro Iwata, Masaaki Kitaguchi, Hideki Kohri, Taku Matsushita, Daisuke Miura, Yoshiyuki Miyachi, Hirohiko M. Shimizu, Masaru YosoiComments: 18 pages, 7 figures, Resubmitted to Review of Scientific InstrumentsSubjects: Instrumentation and Detectors (physics.ins-det)
- [105] arXiv:2402.10932 (replaced) [pdf, ps, other]
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Title: Roadmap on Data-Centric Materials ScienceAuthors: Stefan Bauer, Peter Benner, Tristan Bereau, Volker Blum, Mario Boley, Christian Carbogno, C. Richard A. Catlow, Gerhard Dehm, Sebastian Eibl, Ralph Ernstorfer, Ádám Fekete, Lucas Foppa, Peter Fratzl, Christoph Freysoldt, Baptiste Gault, Luca M. Ghiringhelli, Sajal K. Giri, Anton Gladyshev, Pawan Goyal, Jason Hattrick-Simpers, Lara Kabalan, Petr Karpov, Mohammad S. Khorrami, Christoph Koch, Sebastian Kokott, Thomas Kosch, Igor Kowalec, Kurt Kremer, Andreas Leitherer, Yue Li, Christian H. Liebscher, Andrew J. Logsdail, Zhongwei Lu, Felix Luong, Andreas Marek, Florian Merz, Jaber R. Mianroodi, Jörg Neugebauer, Zongrui Pei, Thomas A. R. Purcell, Dierk Raabe, Markus Rampp, Mariana Rossi, Jan-Michael Rost, James Saal, Ulf Saalmann, Kasturi Narasimha Sasidhar, Alaukik Saxena, Luigi Sbailò, et al. (12 additional authors not shown)Comments: Review, outlook, roadmap, perspectiveSubjects: Materials Science (cond-mat.mtrl-sci); Data Analysis, Statistics and Probability (physics.data-an)
- [106] arXiv:2402.13431 (replaced) [pdf, other]
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Title: Game Design Inspired by Quantum Physics: A Case Study on The Quantum Photo BoothAuthors: Sunanda Prabhu Gaunkar, Denise Fischer, Filip Rozpędek, Umang Bhatia, Shobhit Verma, Ahit Kaan Tarhan, Uri Zvi, Nancy KawalekSubjects: Popular Physics (physics.pop-ph); Quantum Physics (quant-ph)
- [107] arXiv:2402.13801 (replaced) [pdf, other]
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Title: Resilience of Hund's rule in the Chemical Space of Small Organic MoleculesComments: Minor revision. Fig.5 revised, SI Tables reorganizedSubjects: Chemical Physics (physics.chem-ph)
- [108] arXiv:2402.17248 (replaced) [pdf, other]
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Title: Synthesizing Particle-in-Cell Simulations Through Learning and GPU Computing for Hybrid Particle Accelerator BeamlinesAuthors: Ryan T. Sandberg, Remi Lehe, Chad E. Mitchell, Marco Garten, Andrew Myers, Ji Qiang, Jean-Luc Vay, Axel HueblComments: 11 pages, 10 figures. Accepted to PASC24 proceedingsJournal-ref: Proceedings of the Platform for Advanced Scientific Computing Conference PASC24 (2024)Subjects: Accelerator Physics (physics.acc-ph); Computational Physics (physics.comp-ph)
- [109] arXiv:2403.11918 (replaced) [pdf, other]
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Title: The hybrid anti-symmetrized coupled channels method (haCC) for the tRecX codeComments: 26 pages, 8 figuresSubjects: Computational Physics (physics.comp-ph)
- [110] arXiv:2403.12275 (replaced) [pdf, other]
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Title: Fast and accurate nonadiabatic molecular dynamics enabled through variational interpolation of correlated electron wavefunctionsSubjects: Chemical Physics (physics.chem-ph); Strongly Correlated Electrons (cond-mat.str-el); Computational Physics (physics.comp-ph); Quantum Physics (quant-ph)
- [111] arXiv:2404.03685 (replaced) [pdf, other]
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Title: Cooperative Evolutionary Pressure and Diminishing Returns Might Explain the Fermi Paradox: On What Super-AIs Are LikeAuthors: Daniel VallstromComments: 23 pages, 1 figure. Added acknowledgement, clarifications, referencesSubjects: Physics and Society (physics.soc-ph); Artificial Intelligence (cs.AI)
- [112] arXiv:2404.12939 (replaced) [pdf, other]
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Title: Superradiant phase transition in a large interacting driven atomic ensemble in free spaceAuthors: Janne RuostekoskiSubjects: Quantum Physics (quant-ph); Quantum Gases (cond-mat.quant-gas); Atomic Physics (physics.atom-ph); Optics (physics.optics)
- [113] arXiv:2404.14399 (replaced) [pdf, other]
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Title: MLQAOA: Graph Learning Accelerated Hybrid Quantum-Classical Multilevel QAOAComments: 18 pages, 3 figures, 4 tablesSubjects: Quantum Physics (quant-ph); Computational Engineering, Finance, and Science (cs.CE); Computational Physics (physics.comp-ph)
- [114] arXiv:2404.17449 (replaced) [pdf, ps, other]
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Title: On the Meaning of Local Symmetries: Epistemic-Ontological DialecticsComments: 21 pagesSubjects: History and Philosophy of Physics (physics.hist-ph); General Relativity and Quantum Cosmology (gr-qc); High Energy Physics - Theory (hep-th); Differential Geometry (math.DG)
- [115] arXiv:2404.17788 (replaced) [pdf, ps, other]
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Title: Reconfigurable collective resonances induced by liquid crystals in dielectric metasurfacesComments: 21 pages, 12 figuresSubjects: Optics (physics.optics); Applied Physics (physics.app-ph)
- [116] arXiv:2404.18582 (replaced) [pdf, ps, other]
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Title: Dressing vs. Fixing: On How to Extract and Interpret Gauge-Invariant ContentSubjects: History and Philosophy of Physics (physics.hist-ph); High Energy Physics - Phenomenology (hep-ph)
- [117] arXiv:2404.18709 (replaced) [pdf, other]
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Title: Three-state Opinion Dynamics for Financial Markets on Complex NetworksAuthors: Bernardo J. Zubillaga, Mateus F. B. Granha, André L. M. Vilela, Chao Wang, Kenric P. Nelson, H. Eugene StanleyComments: 15 pages, 14 figuresSubjects: Physics and Society (physics.soc-ph); Statistical Mechanics (cond-mat.stat-mech); General Economics (econ.GN)
- [118] arXiv:2404.18916 (replaced) [pdf, ps, other]
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Title: Observation of Generalized t-J Spin Dynamics with Tunable Dipolar InteractionsAuthors: Annette N. Carroll, Henrik Hirzler, Calder Miller, David Wellnitz, Sean R. Muleady, Junyu Lin, Krzysztof P. Zamarski, Reuben R. W. Wang, John L. Bohn, Ana Maria Rey, Jun YeSubjects: Quantum Gases (cond-mat.quant-gas); Atomic Physics (physics.atom-ph)
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