Physics and Society
The number of communities in real networks grows as a power law of their size
Alexei Vazquez
Most networks, from friendships to the internet, break up into communities: groups of nodes more densely connected to one another than to the rest. A basic question has remained open: how many communities should a network have, and how does that number grow with size? Simple models bracket the possibilities. In a small-world network built from dense modules – a caveman graph of cliques – each module is a community, so the number grows in proportion to size, as $n$. In self-similar, fractal networks it grows far more slowly, as the square root. Real networks could lie anywhere between. Here we measure the number of communities across close to a hundred real networks spanning four orders of magnitude, from a $34$-member club to millions of nodes, and within individual systems followed over decades as they grow. We find a power law with an exponent between one half and two thirds – above the fractal value and below the linear limit. Simple models of network growth by local rules reproduce the same super-fractal exponent, a stable and measurable property of network organization. In short, network
evolution herds a system's components into clusters, whose number grows as a power law of size.
Read the full abstract ▾
General Physics
Quantum number conservation: a tool in the design and analysis of high energy experiments
D.J.Newman
The Clifford Unification
algebra $Cl_{7,7}$ is shown to provide a unified description of all the elementary
fermions and
hadrons in terms of seven binary
quantum numbers. Four of these are defined in existing theories, namely
spin-direction,
fermion/anti-
fermion pairing and the two commuting generators in the SU(3) description of
quark colour. A $Cl_{3,3}$ sub-
algebra integrates the $Cl_{1,3}$ space-time and Dirac
algebras providing a new definition of time direction and identifying parity as a new
quantum number. A further two
quantum numbers are related to the commuting generators of an SU(3) description of
fermion generations. All seven are conserved in the decays and interactions of charged particles, suggesting that
quantum number conservation provides a useful tool in the design and interpretation of high energy experiments. This is especially relevant when neutral particles and parity are involved.
Read the full abstract ▾
General Physics
Growth-of-Structure Constraints on the Variable Chaplygin Gas Model
Rishabh Jain, Shruti Thakur and Geetanjali Sethi
A unified description of dark matter and the late-time acceleration of the Universe offers an attractive framework for explaining the dark sector. Among such models, the Variable Chaplygin Gas (VCG) model provides a unified description but faces challenges, particularly in the
evolution of cosmological perturbations. We investigate the
evolution of linear density perturbations in the VCG model assuming adiabatic perturbations and constrain its parameters using recent $f\sigma_8$ growth measurements within a Markov Chain Monte Carlo (MCMC) framework. Gaussian priors are adopted from our previous analysis of background observations, including Type Ia
supernovae (Pantheon),
baryon acoustic oscillations (BAO), Hubble parameter $H(z)$ measurements, fast
radio bursts (FRB), and gamma-ray bursts (GRB). We find that growth data favour a markedly different region of the parameter space than the background observations. In particular, the growth analysis prefers a substantially larger value of the model parameter $n$ ($n \simeq 2.3$) compared with the background constraint ($n \sim 1$). This tension indicates that parameter values providing an excellent fit to the background expansion fail to simultaneously reproduce the observed growth of
cosmic structures. Our results demonstrate that growth-of-structure observations provide a stringent and independent test of unified dark sector models and underscore the importance of combining background and perturbation data when assessing the cosmological viability of the Variable Chaplygin Gas model.
Read the full abstract ▾
Physics and Society
Quantized Mereology
Thomas Bittner
This paper investigates quantized mereology, which merges
quantum information theory with classical mereology, the formal analysis of the part-whole relationship. It emphasizes that information about crisp mereological relations is captured by classical bits, whereas mereological vagueness involves the use of
quantum bits, or
qubits, to capture mereological information. Transitioning from classical bits to
qubits offers a new understanding of part-whole relations among entities that are subject to mereological vagueness. This paper methodically studies the quantized mereology that arises from the classical RCC5 formalism, one of the most widely studied formalisms in Qualitative
Reasoning (QR), a subfield of Artificial Intelligence. The argument is made that this method can be extended to quantize more sophisticated QR formalisms, mirroring how strategies are used in physics to transition from classical to
quantum systems. The study explores: (i) the conversion of bits to
qubits while understanding that these (qu)bits convey mereological information; (ii) the representation of
qubit states via set partitions, acknowledging that set theory aligns more closely with classical logic than with the complex vector spaces employed in
quantum physics; (iii) demonstrating that classical QR formalisms can be seen as special cases within quantized formalisms; and (iv) showing that
qubits more effectively encapsulate information about vague phenomena.
Read the full abstract ▾
General Physics
A Covariant Curvature-History Field Formulation for State-Dependent Infinite-Derivative Gravity
G.M. Rhythm
We construct a covariant auxiliary-field formulation for state-dependent infinite-derivative
gravity. Null-congruence
curvature-history integrals provide a natural motivation for state dependence, but they suffer from variational ambiguities and loss of smooth metric dependence in the presence of caustics and branch changes. We replace the curve-dependent history variable by a local scalar field \(C(x)\) satisfying a covariant
hyperbolic equation sourced by the Kretschmann invariant. The history equation is enforced at the level of the action by a conjugate auxiliary field \(\chi(x)\). Since the dynamical nonlocality scale depends on \(C(x)\), the variation of the nonlocal form factor involves noncommuting operators; this variation is evaluated using Duhamel's formula. Treating \(C\) and \(\chi\) as independent local fields, we derive the coupled field equations and show that the stress-energy exchange between the nonlocal
memory sector and the auxiliary history sector cancels on shell. The resulting local Noether identity ensures covariant conservation of the combined
memory-history stress-energy tensor and compatibility with the contracted Bianchi identity.
Read the full abstract ▾
Instrumentation and Detectors
Contribution of cosmic alphas to generation of albedo neutrons and gammas in lunar regolith: A computational study based on GEANT4 simulations
Harshala Gaonkar and A. Ilker Topuz
The lunar surface is constantly and directly exposed to
Galactic Cosmic Rays (GCRs) due to the lack of the atmosphere and the
magnetic field around it. The high-energetic alpha particles subsequently contribute to the generation of the secondary
neutrons through either the spallation reaction or the low-energetic $(\alpha, n)$ process along with the
cosmic protons. In this study, the contribution of the alpha particles to the production of the albedo
neutrons as well as the albedo gamma rays in the lunar regolith is studied by using the Monte Carlo simulations based on the GEANT4 toolkit. The incident alpha particles are referenced from the PAMELA spectrometer over the interval between 0.14 and 52 GeV and executed as a probability-based primary particle source. The present simulations demonstrate the production of the albedo
neutrons and gamma rays upon the process of
cosmic alpha irradiation in the lunar regolith. The albedo
neutron production is predominantly situated within the near-surface region of the lunar regolith and progressively diminishes with the increasing depth. The population of the secondary
neutrons is primarily distributed over the low-energy region and reduces towards the high energies. These results imply that the
cosmic alpha particles have also quantifiable contribution in the generation of the secondary radiation at the lunar surface together with the
cosmic protons, and this study demonstrates a computational framework in the evaluation of the lunar albedo, the radiation transport, the surface composition, and the radiation environment for the further lunar exploration missions.
Read the full abstract ▾
Instrumentation and Detectors
Femtoscopy Measurement with S$\pi$RIT TPC in Radioactive BeamHeavy-ion Collisions
Y. J. Wang, C. K. Tam, Z. G. Xiao et al. (+64 more)
Femtoscopy is a powerful tool for exploring the dynamic emitting structure in heavy-ion collisions, while radioactive beam heavy-ion collisions enable the investigation of
nuclear matter under extreme isospin conditions. Here, we successfully perform femtoscopy measurements using the S$\pi$RIT Time Projection Chamber (TPC). A dedicated correction scheme for track merging and splitting is proposed, which is well applicable to rectangular TPCs housed inside dipole magnets and effectively improves the reconstructed correlation functions at small relative momenta. Focusing on the
proton-
proton (p-p) correlation function in the 270 MeV/u $^{132}\text{Sn}+^{124}\text{Sn}$ system, we successfully apply the track merging and splitting correction; additionally, the TPC angular acceptance exhibits a negligible impact on the correlation function. A systematic uncertainty quantification framework is established. The experimental results of the p-p correlation function confirm the feasibility of the S$\pi$RIT TPC for femtoscopy measurements and provide technical support for high-precision femtoscopy studies using rectangular TPCs in radioactive beam heavy-ion collisions.
Read the full abstract ▾
All authors Y. J. Wang, C. K. Tam, Z. G. Xiao, W. G. Lynch, C. Y. Tsang, J. Barney, G. Jhang, J. Estee, M. B. Tsang, R. S. Wang, M. Kaneko, J. W. Lee, J. Park, Z. Chajęcki, G. Verde, T. Isobe, M. Kurata-Nishimura, T. Murakami, D. S. Ahn, L. Atar, T. Aumann, H. Baba, K. Boretzky, J. Brzychczyk, G. Cerizza, N. Chiga, N. Fukuda, I. Gasparic, B. Hong, A. Horvat, K. Ieki, N. Inabe, Y. J. Kim, T. Kobayashi, Y. Kondo, P. Lasko, H. S. Lee, Y. Leifels, J. Łukasik, J. Manfredi, A. B. McIntosh, P. Morfouace, T. Nakamura, N. Nakatsuka, S. Nishimura, H. Otsu, P. Pawłowski, K. Pelczar, D. Rossi, H. Sakurai, C. Santamaria, H. Sato, H. Scheit, R. Shane, Y. Shimizu, H. Simon, A. Snoch, A. Sochocka, T. Sumikama, H. Suzuki, D. Suzuki, H. Takeda, S. Tangwancharoen, H. Toernqvist, Y. Togano, S. J. Yennello, Y. Zhang
Fluid Dynamics · Cross-listed from nlin.CD
A Measure-Theoretic Approach to Spontaneous Stochasticity
Wandrille Ruffenach, Eric Simonnet and Nicolas Valade
Spontaneous stochasticity (SpSt), originating in Richardson's picture of turbulent dispersion and Lorenz's Eulerian view of finite-time loss of predictability, was later formulated under this name by Gawędzki and collaborators and developed in shell models by Mailybaev and collaborators. Whether it occurs in fully developed
turbulence remains a major open question. Beyond a few specific classes of systems, however, SpSt has lacked a general mathematical definition. We introduce a measure-theoretic formalism in which it is understood as a measure-selection principle. Given an inviscid problem, a well-posed regularization, and an ambient measure, we study the pushforward of that measure by the regularized flow. Strong SpSt occurs when these pushforward measures converge to a non-Dirac probability law, replacing classical deterministic selection by statistical selection. For finite-dimensional systems, we establish several structural results. Our central attainability
theorem shows that, whenever the inviscid problem is nonunique, any probability measure supported on the set of inviscid states can be selected as the limiting law of a suitable regularization. We also identify singular sets in the inviscid dynamics, detected through Dini-type directional growth, as necessary obstructions underlying nonuniqueness. We analyze the relation between SpSt and sensitivity to initial data, clarifying the scope and limitations of
turbulence-inspired finite-time separation criteria. Finally, we develop a renormalization-(semi)group viewpoint in which limiting statistics arise as statistical attractors. Explicit examples illustrate how ambient measures, inviscid singularities, regularization scales, and initial-data sensitivity interact in the emergence of SpSt.
Read the full abstract ▾
Optics
Dynamics of confined acoustic phonon modes in nanocrystalline silicon membranes
Tiago E. C. Magalhães, Tânia M. Ribeiro, Oili M. E. Ylivaara et al. (+2 more)
We report femtosecond time-resolved measurements of confined acoustic
phonons in free-standing nanocrystalline silicon membranes and compare them with the crystalline silicon counterpart. While the latter exhibit well-resolved higher-order modes, a strong suppression of these modes is observed in nanocrystalline samples. The suppression is strongly frequency dependent and becomes more pronounced as the
phonon wavelength approaches the characteristic grain size. Analysis of the
phonon lifetimes reveals an additional frequency-dependent scattering mechanism in nanocrystalline silicon, with a scattering rate that scales approximately as $f^2$, where $f$ is the
phonon frequency. The measured sound velocity is consistent with previous reports for nanocrystalline silicon and indicates an effective elastic response arising from multiple crystallographic orientations. These results establish coherent
phonons as a sensitive probe of microstructure-dependent scattering in nanocrystalline materials and indicate that grain boundaries act as an effective spectral filter for high-frequency acoustic
phonons.
Read the full abstract ▾
All authors Tiago E. C. Magalhães, Tânia M. Ribeiro, Oili M. E. Ylivaara, Jouni Ahopelto, Clivia M. Sotomayor Torres
Data Analysis and Statistics · Cross-listed from math-ph
On Factorizing Aggregate Counting Distributions into Independent Latent Processes
Israel Klich
Given only the probability distribution of an aggregate counting variable, what independent latent counting processes are compatible with the observation? Equivalently, when does a probability-generating function admit a factorization into normalized
polynomials with nonnegative coefficients? We develop a mathematical theory of such positive factorizations. We introduce the positive factorization poset, whose elements are all positive factorizations ordered by refinement, and define the factorization
entropy, measuring the maximal latent Shannon
entropy compatible with the observed distribution. We prove a sharp
entropy inequality, characterize the equality case by injectivity of the latent addition map, show that
entropy optimization may be restricted to maximal atomizations, and exhibit examples where distinct maximal atomizations have different
entropy. We further establish support-based obstructions to positive factorization, characterize the real-rooted and Hurwitz-stable sectors, prove a local stability
theorem for coprime factorizations, determine exactly the factorable regions in degrees two and three, obtain an exact quartic Hurwitz volume, and investigate the geometry of the factorable region inside the probability simplex through exact calculations and Monte Carlo experiments. These results identify the positive factorization poset as a natural algebraic object associated with probability-generating functions and provide a framework for studying latent independent structure in aggregate counting statistics.
Read the full abstract ▾
Computational Physics · Cross-listed from cs.ET
Unified Uncertainty Quantification Framework Bridging Noisy Quantum Backends Across Variational Quantum Algorithms and Quantum Signal Processing
Priyabrata Senapati, Vibin Abraham, Qiang Guan et al. (+1 more)
We present an uncertainty quantification (UQ) framework for application level benchmarking and characterization of noisy
quantum backends. The framework compares two workload classes under one statistical pipeline: noisy intermediate scale
quantum (NISQ) variational
quantum algorithms (VQAs) and
Quantum Singular Value Transformation (QSVT) based Green's function reconstruction. For the VQA branch, we evaluate ten
benchmark families spanning chemistry, optimization, simulation, compiling, linear solving, partial differential equations, metrology, error correction,
tomography, and channel fidelity estimation. For the QSVT branch, we reconstruct orbital resolved Green's functions and spectral peaks from a block encoded real time propagator. The workflow combines
Bayesian optimization, posterior distribution refinement, sensitivity analysis, robust parameter density estimation, backend ranking, noise correlation, and resource estimation analysis. Instead of reporting only one best parameter vector, the framework identifies robust parameter regions, residual gaps to ideal behavior, backend specific failure modes, and calibration sensitive uncertainty. The result is a common
benchmark for variational and non-variational workloads that measures how reliably each backend reaches useful task level behavior.
Read the full abstract ▾
All authors Priyabrata Senapati, Vibin Abraham, Qiang Guan, Bo Peng
Optics
Smooth-Curvature Bend Design Guided by Variational Analysis for Adiabatic Multimode Integrated Photonics
Yutong Shi, Shijin Yu, Ye Huang et al. (+2 more)
Multimode photonic integrated
circuits enable ultralow-loss on-chip optical interconnects and microwave-photonic processing, yet waveguide bends dominate both chip footprint and excess loss. A high-performance multimode waveguide bend (MWB) must transmit the working mode with low loss while suppressing intermodal coupling, forcing a trade-off among bending radius, operating bandwidth, and fabrication tolerance. Here we formulate constant-width MWB design as a
curvature-dependent variational problem. By constructing a figure of merit that incorporates higher-order-mode excitation, fundamental-mode mismatch, and sidewall field intensity, we derive a necessary condition for adiabatic optimality: the
curvature profile must approach infinite differentiability throughout the bend, including its junctions with the input and output straight waveguides. This condition explains the limitations of circular and Euler bends and motivates a smooth
polynomial curvature (SPC) family with a closed-form beta-function representation. We further introduce an optimized SPC hybrid (SPCh) bend that balances junction smoothness and the interior
curvature gradient. On the 220 nm silicon-on-
insulator platform, SPCh bends achieve a mode extinction ratio below $-37$ dB from 1500-1600 nm at an effective radius of $16\,\mu\mathrm{m}$, providing more than 22 dB stronger mode suppression than a representative Euler bend at the same radius. The simulated response remains robust to $\pm 60$ nm waveguide-width deviations. Fabricated SPCh-based microring resonators reach an intrinsic quality factor of up to $7.53 \times 10^6$ and a free spectral range of up to 100 GHz through a standard silicon foundry process. The resulting design strategy provides compact, broadband, and fabrication-tolerant multimode bends for high-density optical interconnects and microwave-photonic systems.
Read the full abstract ▾
All authors Yutong Shi, Shijin Yu, Ye Huang, Yuan Yu, Xinliang Zhang
Physics and Society · Cross-listed from q-bio.PE
Infectious Disease Induces Emergent Oscillations, Extinction and Changes in Community Persistence in a Food Chain
Hooman Saveh and Fakhteh Ghanbarnejad
Food webs have been extensively studied from both ecological and mathematical aspects. However, most of the models studied in this area do not capture the effects of infectious diseases simultaneously. Recently, the idea of including an infectious disease in a food web model has been investigated. We study and simulate a small food chain consisting of only prey, predators, and apex predators governed by the generalized Lotka-Volterra equations, and we implement the Susceptible-Infected-Recovered (SIR) model on only one of the species at a time in the food chain. To study the effects of an infectious disease on the food chain, we introduce a new parameter that increases the predation rate by a factor of $w$ and decreases the hunting rate by a factor of $1/w$ for infected species. When the infectious disease is present in predators, we observe that predators do not become extinct under any set of parameters; however, an oscillation in their population size occurs under some circumstances, which we do not observe in ordinary SIR or the generalized Lotka-Volterra equations alone. When an infectious disease is present in apex predators, oscillations in the population size do not happen; but if the set of parameters is in a specific range the apex predators may become extinct. Furthermore, the chance of survival of the community, known as community persistence, increases for the predators and decreases for the apex predators.
Read the full abstract ▾
Accelerator Physics
Foundation of Three-Dimensional Spiral Beam Injection Using Canonical Angular Momentum and Symplectic Eigen-Modes
Hiromi Iinuma
Aiming for high injection efficiency in three-dimensional spiral injection, the underlying physical principles governing beam formation and matching should be systematically organized within a unified canonical framework. However, a general theoretical framework explaining why particular beam distributions become naturally matched has not yet been established. In this work, a canonical description of three-dimensional spiral injection is developed based on the eigensystem of the
symplectic covariance
matrix $J\Sigma$. Canonical modal families are introduced to represent the underlying beam structure, and statistically broadened beam distributions are synthesized around the corresponding modal skeletons while preserving their canonical
topology. Unlike conventional beam-matching methods based on Twiss parameters or eigen-emittance analysis, the proposed framework employs canonical
symplectic modes as design variables for beam-family synthesis. It provides a unified description of beam geometry and canonical angular momentum in terms of canonical
symplectic modes, and enables beam distributions to be interpreted in terms of their dominant modal structures. Beyond providing a canonical design representation of three-dimensional spiral injection, this approach establishes a direct connection between canonical beam dynamics and experimentally realizable injection beams, thereby providing a theoretical basis for systematic beam synthesis and injection-beam design. The framework further enables the systematic representation, synthesis, and evaluation of statistical distributions of spiral-injection beams in canonical modal space.
Read the full abstract ▾
Optics · Cross-listed from cs.NI
Transition-Aware Routing in Hybrid Hollow-Core/Single-Mode Fiber Networks: A Cost–Throughput Investigation
Md Ghulam Saber and Zhiping Jiang
Incremental deployment of hollow-core fiber (HCF) in single-mode-fiber (SMF) networks introduces a routing tradeoff: reducing HCF-SMF transitions can improve physical-layer feasibility, but overly transition-averse routing incurs harmful path detours. We study this tradeoff using a common event-driven simulator that compares six protected routing schemes spanning fiber-blind, generalized signal-to-noise ratio (GSNR)-aware, and explicitly transition-aware designs on hybrid HCF/SMF
topologies. The model includes a per-transition GSNR penalty and an exploratory splice-failure availability term. Across six reference
topologies, five HCF deployment fractions, and dynamic loads at 300 Erlang, the strongest transition minimizers, transition-penalty-aware routing (TPAR) and the GSNR/fiber-transition joint scheme (GFJ), halve the mean transition count at a 20-25% carried-traffic penalty. Among the intermediate designs, GSNR- maximal routing with transition-aware reranking (GMR-T) cuts transitions by approximately 22% relative to distance-adaptive routing and spectrum assignment (DA-RSA) at a 3% throughput cost, while bounded-detour TPAR (BD-TPAR) cuts transitions by approximately 11% at only a 1% cost. Deployment pattern also matters: contiguous HCF rollout lowers transitions by approximately 40% on average while improving carried traffic, reducing the benefit of aggressive transition-aware routing. These results support BD-TPAR as a practical default under fragmented deployment, GMR-T as a lower-complexity alternative, and TPAR or GFJ only where the external cost of transitions is high.
Read the full abstract ▾
Fluid Dynamics
Interfacial-Thermo-Fluid-Adhesion Dynamics of Evaporating Capillary Bridges between Curved Surfaces
Arnov Paul, Subhadeep Mondal and Purbarun Dhar
We probe the evaporation mechanism, and the associated adhesion dynamics of
liquid capillary bridges connecting two curved, solid substrates. The coupled thermo fluid species transport and the transient
evolution of capillary adhesion during evaporation are systematically examined. An accurate, fully coupled transient numerical framework is developed, wherein the
equilibrium capillary profiles are first determined from level set method. Next, the evaporation is simulated via Arbitrary Lagrangian Eulerian ALE framework to accurately track the moving
liquid vapor interface. The combined influence of substrate
curvature, surface wettability, and solid thermal conductivity on evaporation and capillary adhesion character is comprehensively analysed. The simulation methodology is robustly validated against published literature for capillary profiles, evaporation rates, and capillary forces, demonstrating good agreement. Our results reveal that the evaporation characteristics of both hydrophilic and superhydrophobic SH
liquid bridges are strongly governed by substrate
curvature and thermal conductivity, and increasing values pose favourable condition for augmented interfacial mass transfer rate. The innately non uniform vapour flux generates spatially varying evaporative cooling, producing surface tension gradients that drive internal thermo capillary circulation. A non dimensional scaling analysis shows that Marangoni flow dominates buoyancy induced flow throughout. Also, increasing substrate
curvature decreases the overall capillary force, owing to the reduced
curvatures of the
liquid bridge, while the temporal
evolution of the adhesion force is strongly influenced by both substrate
curvature and wettability.
Read the full abstract ▾
Applied Physics · Cross-listed from quant-ph
Towards a monolithic platform for coupling superconducting circuits to low-loss microwave phonons in AlScN on 4H-SiC
Yuanchen Deng, William W. Roberts, Sueli Skinner-Ramos et al. (+12 more)
Hybrid superconducting-
phonon quantum processing is promising for cavity QED, measurement-based
quantum computing, and other
quantum applications. Relative to microwave
photons at the same frequency,
phonons can provide ultra-compact footprints, extremely low losses, and greater connectivity.
Phonons can also couple strongly to superconducting
circuits through the piezoelectric effect. However, this promise rests on scalable platforms that achieve these benefits without degrading superconducting
circuit performance. This motivates a monolithic platform combining low phononic loss, strong electromechanical coupling, and superconducting-
circuit compatibility without requiring suspended phononics. Here, we characterize a monolithic
quantum acoustic platform combining aluminum superconducting
circuits on exposed silicon carbide (SiC) with piezoelectric aluminum scandium nitride (AlScN) on SiC for integrated phononics. This architecture is enabled by selective removal of AlScN from selected chip regions, allowing aluminum superconducting microwave resonators to be fabricated directly on the SiC while preserving adjacent AlScN-on-SiC regions for
phonon transduction. The resulting Al-on-SiC resonators exhibit a coherent lifetime of 2.9 {\mu}s, demonstrating compatibility with aluminum superconducting
quantum devices. In parallel, cryogenic surface acoustic delay-line measurements on the retained AlScN-on-SiC regions show low phononic propagation loss at 4.05 GHz, corresponding to an estimated
phonon lifetime of 7.6 {\mu}s. Together with a previously demonstrated electromechanical coupling coefficient of about 4.3% and a theoretical upper bound of 8%, these results establish Al-on-SiC/AlScN-on-SiC as a promising monolithic platform for integrating superconducting microwave
circuits with piezoelectric phononic components for
quantum acoustic networking and hybrid
quantum systems.
Read the full abstract ▾
All authors Yuanchen Deng, William W. Roberts, Sueli Skinner-Ramos, Dalton Anderson, Katherine Hewey, Xingyu Du, Michael Miller, Brandon Smith, Hwijong Lee, Pingping Chen, Charles Thomas Harris, Roy H. Olsson III, Lisa Hackett, Rupert Lewis, Matt Eichenfield
Plasma Physics · Cross-listed from quant-ph
An end-to-end quantum algorithm for weakly nonlinear plasma physics with superquadratic speedup
Bjorn K. Berntson, David Jennings, Matteo Lostaglio et al. (+1 more)
Nonlinear kinetic
plasma simulation is high-dimensional and classically demanding, while
quantum algorithms face different bottlenecks:
embedding nonlinear dynamics into a linear computation, loading dense field-interaction data, and efficiently extracting information. We present an end-to-end
quantum algorithm, with rigorous convergence guarantees, for a weakly nonlinear kinetic
plasma model. The system describes a 3D electron-ion
plasma with adiabatic electrons, kinetic ions, Debye screening, and Krook relaxation. After
Fourier-Hermite truncation, the dynamics reduces to a high-dimensional quadratic ordinary differential equation. To tackle
quantum bottlenecks we combine three key ingredients. First, we use a
plasma free energy to identify a Lyapunov transform under which a Carleman linear
embedding converges exponentially in the truncation order within a certified weakly nonlinear regime. Second, we develop a hierarchical block-encoding protocol for dense
matrices, exploiting the spatial decay of the field to avoid
polynomial overhead from sparse access encodings. Third, we introduce a subroutine for information extraction that exploits nonlinear components encoded in the full Carleman history state to improve the estimation of linear observables. We construct a
quantum algorithm to estimate the spacetime-averaged kinetic energy using $\widetilde{O}\!\left( N_F N_H^{1/2} \operatorname{polylog}\!\left(\frac{T}{\epsilon}\right)\frac{1}{\epsilon}\right)$ gates and $\widetilde{O}\!\left(\log\!\left(N_F N_H^{1/2}T\right)\log\!\left(\frac{1}{\epsilon}\right)\right)$
qubits, where $N_F$ and $N_H$ are the
Fourier and Hermite cutoffs. Relative to a
Fourier-Hermite spectral solver, this yields exponential
memory savings and superquadratic improvements in time. Together, these results establish a controlled nonlinear
plasma benchmark for
quantum simulation.
Read the full abstract ▾
All authors Bjorn K. Berntson, David Jennings, Matteo Lostaglio, Scott Parker
Physics Education
Assessing AI in Introductory Physics Problem Solving
Amir Bralin and N. Sanjay Rebello
Reasoning or inference-scaling models are the new generation of Large
Language Models (LLMs) capable of complex problem solving. To investigate their problem-solving capability in physics, we evaluated model o4-mini by OpenAI on solving traditional, end-of-chapter problems from Halliday and Resnick's "Fundamentals of Physics," spanning core topics in the undergraduate physics curriculum. Performance was analyzed across modality and problem difficulty. The model solved the problems with overall accuracy of about 90%, but performance depended strongly on representation: accuracy was much higher on text-only problems (96%) than on problems requiring coordinated interpretation of text and images (79%). Accuracy also declined significantly as the problem difficulty increased from low to medium to high. These results show that state-of-the-art LLMs can solve much of the standard introductory physics problems, but that their performance remains uneven and constrained by problem modality and problem difficulty.
Read the full abstract ▾
Fluid Dynamics
Orientation Dynamics of Rigid Fibers in a Microfluidic Burgers-like Vortex
Marine Aulnette, Mathis Coutadeur, Clément Bielinski et al. (+2 more)
Fiber suspensions are common in biological and environmental flows and are widely used in industrial applications. Fiber transport and orientation dynamics are affected by interactions with the surrounding fluid and strongly depend on the nature of the flow. The complexity of realistic flows, which are often heterogeneous or time-dependent, hinders a full understanding of fiber dynamics. In this study, we combine microfluidic experiments, theory and numerical simulations to investigate the orientation dynamics of rigid neutrally buoyant fibers in a well-controlled model system, a streamwise stationary
vortex at moderate Reynolds number. Despite the three-dimensional nature of the flow, the orientation dynamics are remarkably simple: the fiber orientation is accurately described by Jeffery equations coupled with the Burgers-
vortex model over a large range of particle Reynolds number. We show that fibers undergo uniform precession about the
vortex axis driven by fluid vorticity while simultaneously aligning with the latter due to strain in the
vortex core. These two motions are decoupled, with the
alignment timescale determined by the local strain rate and the fiber aspect ratio. Finite particle size and inertia induce weak deviations from the base flow streamlines while leaving the orientational dynamics largely unaffected. These results establish a simple framework for understanding the behavior of elongated particles in stretched
vortex flows, which constitute key building blocks of
turbulence.
Read the full abstract ▾
All authors Marine Aulnette, Mathis Coutadeur, Clément Bielinski, Blaise Delmotte, Anke Lindner
Instrumentation and Detectors
Comprehensive study of timing resolution in plastic scintillator detectors with wavelength-shifting fiber and silicon photomultiplier readout
Haohui Che and Guang Yang
We present a comprehensive study of the timing resolution achievable in plastic scintillator detectors read out through wavelength-shifting (WLS) fibers coupled to silicon photomultipliers (SiPMs), combining a semi-analytical framework, toy Monte Carlo validation, and full Geant4 optical
photon simulation. The analytical model traces the complete
photon detection chain: scintillation emission, WLS fiber re-emission, optical transit time dispersion, SiPM single-
photon time resolution, and electronics quantization. It expresses the timing resolution $\sigt$ as a function of the detected photoelectron yield $\Npe$, scintillator decay constants ($\taur$, $\taud$), WLS re-emission time ($\tauwls$), fiber numerical aperture, detector geometry, and readout electronics parameters. The analytical predictions are validated at two levels. First, toy Monte Carlo simulations ($2\times 10^5$ events per parameter point across 80 grid points spanning 8 fiber types and $\Npe$ from 5 to 200) achieve analytical-to-MC agreement of $0.9997 \pm 0.0015$. Second, full Geant4 optical
photon simulations track the entire scintillation, wavelength-shifting, and fiber transport chain in realistic detector geometries, confirming the analytical timing predictions and providing first-principles photoelectron yield calibration. A comprehensive parameter scan covering 7 scintillator materials, 8 WLS fiber types, 5 SiPM models, 5 electronics configurations, 3 readout
topologies, and 3 boundary conditions produces quantitative design maps and lookup tables for detector optimization.
Read the full abstract ▾
Computational Physics · Cross-listed from math.NA
A structure-preserving Numerical Method for the Compressible Resistive-Hall-MHD System
Murtazo Nazarov, Rafael Rodriguez-Velasco and Ignacio Tomas
In this paper, we present a structure-preserving method for the compressible resistive
Hall-magnetohydrodynamics (MHD) model. The differential operator is split into two parts: a hydrodynamic part consisting of the compressible Euler equations, and a
magnetic part consisting of a system coupling the Lorentz force and the induction equation. The method uses continuous Lagrange elements for the Euler part and a curl-conforming finite element space for the
magnetic part. The hydrodynamic part preserves the positivity of the density and internal energy, the conservation of total energy, and the minimum principle for the specific
entropy. Owing to the choice of finite elements, the
magnetic part preserves the divergence involution constraint. The fluid part is solved using explicit strong-stability-preserving Runge-Kutta (SSP-RK) methods, whereas the
magnetic part is solved by Crank-Nicholson method, which requires using Newton's method. Coercivity estimates for the Jacobian of the corresponding Newton iteration are presented. We introduce a high-order artificial resistivity to improve the conditioning of the nonlinear residual and the invertibility of the Jacobian. Several challenging
benchmarks, including a smooth whistler wave, the Orszag-Tang
vortex for comparing resistive MHD with resistive
Hall-MHD, and a
magnetic reconnection problem, are solved to validate the robustness and accuracy of the method.
Read the full abstract ▾
Optics
High-resolution single-molecule mass measurement of megadalton assemblies in solution
Tereza Roesel, Evangelos Efraimidis, Niklas Hansen et al. (+5 more)
Resolving heterogeneity in megadalton assemblies requires precise single-molecule mass measurements in solution. Mass photometry infers mass from individual molecular surface-landing events, and event-to-event measurement variability limits precision. Nanofluidic scattering microscopy overcomes this limitation by continuously tracking molecules in motion, enabling repeated sampling and temporal averaging of these fluctuations. Benchmarking with 4.5 MDa DNA origami demonstrates up to a fourfold improved resolution, approaching the performance of ensemble-averaged native mass spectrometry.
Read the full abstract ▾
All authors Tereza Roesel, Evangelos Efraimidis, Niklas Hansen, Yulia Yancheva, Miroslav Hekrdla, Katarzyna M. Tych, Vladimira Petrakova, Barbora Spackova
Computational Physics · Cross-listed from quant-ph
Worldline-Susceptibility Scheduling for Quantum Annealing Beyond Local-Adiabatic Evolution
Suraj Singh, Lakshya Nagpal, Vikas Chauhan et al. (+1 more)
The performance of
quantum annealing depends critically on how the available annealing time is distributed along the
evolution. Although the Roland Cerf local adiabatic schedule is theoretically optimal, it requires complete knowledge of the instantaneous spectral gap, making it impractical for large optimization problems. We propose a computationally inexpensive surrogate schedule based on the worldline magnetization susceptibility measured during simulated
quantum annealing. The susceptibility is obtained directly from
equilibrium Monte Carlo sampling and identifies the critical region of the anneal without requiring spectral information. Using exact diagonalization of Sherrington Kirkpatrick
spin glass instances as ground truth, we show that the resulting schedule consistently outperforms conventional linear annealing and, for a substantial fraction of instances, also surpasses the exact Roland Cerf schedule. We demonstrate that this unexpected behaviour originates from two finite time failure modes of exact local adiabatic scheduling a boundary gap trap, in which the minimum spectral gap occurs at the end of the anneal, and an oscillatory instability caused by excessively localized time allocation around an interior minimum gap. These results suggest that robust scheduling based on inexpensive
equilibrium observables can outperform exact spectral gap based strategies under realistic finite time conditions. The complete methodology is implemented in the open source Qanneal framework.
Read the full abstract ▾
All authors Suraj Singh, Lakshya Nagpal, Vikas Chauhan, S.R. Hassan
Computational Physics · Cross-listed from cond-mat.str-el
AutoHF: a general Hartree-Fock solver utilizing direct energy minimization with automatic differentiation
Ryan Levy, Brandon Eskridge, Lukas Weber et al. (+2 more)
We present autohf, a general, easy-to-use mean-field solver for
quantum many-
fermion Hamiltonians. It allows the user to bypass the process of deciphering the mean-field form for each many-body
Hamiltonian $H$ and thus avoid setting up a tailored program for each $H$. Rather, autohf finds the optimal Slater determinant $|\Psi\rangle$, written in terms of orbital coefficients and subject to
symmetry constraints, by directly minimizing the variational energy $\langle H \rangle$. By embracing this variational approach, autohf makes use of the growing power of automatic differentiation and optimization tools developed by the machine learning community.
Read the full abstract ▾
All authors Ryan Levy, Brandon Eskridge, Lukas Weber, Miguel A. Morales, Shiwei Zhang
Plasma Physics · Cross-listed from astro-ph.HE
Ultra-long simulations of collisionless relativistic shocks in front-comoving frame: evidence for a steady state and its properties
Mikhail Garasev and Evgeny Derishev
We present a series of unprecedently long 2D3V PIC simulations of unmagnetized relativistic $e^{-}e^{+}$-pair shocks performed in a front-comoving frame. By implementing a moving-wall boundary condition in the downstream together with continuous injection at the upstream boundary, we maintain a fixed simulation domain size, opening the way to perform substantially longer simulations. Our longest runs extend beyond $100000\,\omega_p^{-1}$, exceeding the duration of the previously published simulations by a factor of several. Across a diverse set of simulations – varying upstream/downstream lengths, transverse sizes, and particle-per-
cell counts – we find strong evidence that the shock approaches an asymptotic, time-independent state. In the downstream region, the steady state depends only on the upstream temperature at the injection boundary and does not depend on a particular numerical realization. The upstream precursor evolves slower and retains a dependence on the simulation's upstream length, that may be of minor observational consequence, since radiation from astrophysical shocks predominantly originates from the downstream region. We also find that
Fermi-type acceleration is limited in energy and a true power-law tail never forms. Another important finding is that the downstream
magnetic field has a
soliton-like structure, where individual
magnetic domains evolve independently, each comprising a compact, highly magnetized core embedded within an extended, weakly magnetized region. The
magnetic-field distribution around the centers of these spots has approximately Lorentzian profile.
Read the full abstract ▾
History and Philosophy of Physics
The orientation of the Amazonian geoglyphs as a clue for their interpretation
Giulio Magli
Amazonian earthworks, also called geoglyphs, are thousands of man-made earthen structures, mostly of geometrical shape, which progressively emerged from the tropical forest due to progressive deforestation. They were probably built between the fifth century BC and the end of the first millennium AD, but archaeological investigation on the culture of their builders is yet at the beginning. Nevertheless, a ceremonial rather than practical function seems likely, at least for those having a very regular shape. In the present paper, simple remote-sensing technique, combined with the methodological approach of modern Archaeoastronomy, are applied to study for the first time their orientation. The analysis takes in consideration virtually all known squared and rectangular structures for a total of 326 earthworks. The results show without doubts a non-random choice for their orientation and a clear interest of their builders for the annual cycle of the Sun.
Read the full abstract ▾