Quantum Physics
Programmable photonic state fusion via heralded storage of asynchronously generated resources
Mustafa Gündoğan and Dennis Rätzel
Probabilistic photonic sources generate elementary states in different trials, whereas multiphoton protocols require them to interfere in common temporal modes. We propose a fusion protocol that overcomes this mismatch by successively loading independently heralded photonic states into active storage loops. Conditioning on
vacuum in monitored dump modes selects events in which each newly generated state is transferred into the same circulating modes as the
photons already stored, thereby removing its generation time label. Provided the two alternatives of each elementary state undergo the same loading transformation, the accumulated state is described by a product of programmable linear factors, allowing a target superposition to be constructed by
polynomial factorization. Adjusting the storage loop coupling as the state grows substantially improves the loading efficiency, changing the faster-than-exponential penalty of fixed balanced couplers to exponential scaling. We apply the protocol to two-
photon path–frequency states for photonic clock interferometry and estimate the detected rate including source waiting time and round-trip loss.
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Materials Science
Constrained Optimization of Higher-Order Cluster-Expansion Hamiltonians for Alloys Using Simulated Bifurcation
Kazuhide Ichikawa, Satoru Ohuchi, Tomoyasu Yokoyama et al. (+2 more)
Identifying ground-state and low-energy atomic configurations is a central problem in
alloy design. The cluster-expansion (CE) method represents configurational energetics on a fixed
lattice as an effective
Hamiltonian; for binary
alloys, higher-order CE models become
polynomial Ising
Hamiltonians. Using Au-Cu as a model binary
alloy, we formulate cubic and quartic cluster-expansion
Hamiltonians as penalty-augmented
polynomial unconstrained binary optimization (PUBO) problems under fixed-composition constraints. We optimize these PUBO problems using SQBM+, a simulated-bifurcation-based solver that can treat higher-order
polynomial binary objectives directly. This direct PUBO treatment avoids the need to construct an explicit quadratic reformulation with auxiliary variables. Composition constraints are imposed through quadratic penalty terms, whose weights are estimated from derivative coefficients of the continuous relaxation of the CE objective.
Benchmark calculations for systems up to 2048 atoms show that SQBM+ robustly obtains low-energy feasible configurations for cubic CE models and remains effective for many quartic instances. Formation-energy convex hulls constructed from the optimized configurations recover the CuAu and Cu3Au ordering trends and reveal finite-size effects at off-stoichiometric compositions. These results demonstrate simulated bifurcation as a practical route to constrained higher-order CE optimization for
alloy configuration search.
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All authors Kazuhide Ichikawa, Satoru Ohuchi, Tomoyasu Yokoyama, Takuma Saito, Yoshiki Matsuda
High Energy Physics (Phenomenology)
An improved partial-wave projection of the one-particle exchange in relativistic three-body scattering
Nicholas C. Chambers and Andrew W. Jackura
A critical component of relativistic three-body scattering amplitudes is the one-particle exchange (OPE) process, wherein a single particle is exchanged between incoming and outgoing two-body subsystems. We present an improved, finite-sum expression for the partial-wave OPE that is valid for three massive, spinless particles in arbitrary angular momentum configurations. A collection of analytic and numerical checks demonstrate that our finite-sum expression reproduces the known properties of the partial-wave OPE, including its threshold scaling behavior and singularity structure. Compared with previous work, this result more efficiently handles the rapid proliferation of partial waves contributing to any total angular momentum $J$, enabling the construction of robust wavesets for three-body amplitude analyses.
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Mathematical Physics · Cross-listed from math.PR
Canonical Local Equilibrium and Cutoff Profiles for the Symmetric Exclusion Process on Discrete Tori
Joe P. Chen
We prove a canonical (or fixed-population) local
equilibrium theorem for the symmetric simple exclusion process on the discrete
torus $\mathbb T_N^D$, $D\ge2$, at particle densities bounded away from $0$ and $1$, uniformly over all deterministic initial configurations with the prescribed particle number. At times \[ t_N(s)=\frac{\log(N^D)+s}{2\gamma_N}, \qquad \gamma_N=2-2\cos\left(\frac{2\pi}{N}\right), \] the Radon–Nikodym density of the process relative to
equilibrium converges in $L^2$ to a canonical exponential tilt generated by the unique small mean-zero calibration field whose one-site marginals match the evolving one-particle heat profile. Consequently, whenever the profile coordinate converges, the corresponding total variation profile is a Gaussian shift. More precisely, for a deterministic initial sequence $(S_N)$, if the covariance-normalized squared amplitude $\mathfrak q_N^{S_N}(s)$ converges to a scalar $\mathfrak q$ at a fixed $s$, then the distance to stationarity converges to $ 2\Phi\!\left({\sqrt{\mathfrak q}}/2\right)-1 $, where $\Phi$ is the standard normal distribution function. The profile coordinate is asymptotically determined by the one-particle eigenspace corresponding to the smallest nonzero
eigenvalue. The proof combines a calibrated canonical comparison, a fixed-degree comparison between independent and exclusion dynamics, and all-degree control obtained from pair energy estimates and preservation of the Strong–Rayleigh property.
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Materials Science
Structural and Electronic Properties of Bulk $\beta$(2H)-GaSe from First-Principles DFT Calculations with van der Waals Corrections
Julián A. Aros-González, Camilo A. Huertas-Archila and Miguel J. Espitia-Rico
Gallium selenide (GaSe) is a layered III-VI
semiconductor whose bulk
crystal serves as the essential energetic reference for modeling the isolated monolayer. We present a systematic density-functional-theory (DFT) study of the centrosymmetric $\beta$(2H)-GaSe polymorph, employing the GGA-PBE functional supplemented with a semiempirical Grimme DFT-D2 dispersion correction to accurately capture the weak van der Waals interlayer coupling. The optimized in-plane
lattice parameter agrees well with experimental values (within about 1.3%), while the out-of-plane parameter c is overestimated by the DFT-D2 correction relative to experiment, a known limitation of this dispersion scheme when the pairwise $C_6$ coefficients are not specifically fitted for the compound class under study. Electronic structure calculations confirm a non-
magnetic, direct-gap profile (1.12 eV). Although this magnitude reflects the well-known underestimation of semilocal functionals, the qualitative band
topology accurately captures the intrinsic two-dimensional carrier confinement within the bulk material. Consequently, this optimized three-dimensional framework provides a consistent energetic baseline for quantifying exfoliation processes, offering a reliable starting point for future theoretical explorations of the two-dimensional limit, such as surface functionalization for potential spintronic applications.
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Astrophysics of Galaxies
From stardust to interstellar grain growth in the first galaxies: a cosmological transition in dust evolution near z ~ 8.9
Denis Burgarella, Tom J. L. C. Bakx, Raffaella Schneider et al. (+7 more)
When and how did
dust begin to shape
galaxies? Motivated by the identification of an apparent
redshift break in
galaxy dust masses, suggesting substantially lower
dust masses at $z \gtrsim 9$, we investigate
dust enrichment during the first billion years of
cosmic history. We aim to determine whether the observed
evolution marks a transition in the dominant
dust-production mechanism and to identify the physical conditions under which such a transition is expected to occur. Using JWST, ALMA, and NOEMA observations, we measure ultraviolet
dust attenuation and
dust masses. We apply a censored change-point analysis and compare the observations with
dust evolution modelling. The analysis identifies a preferred transition near
redshift z ~ 8.9, corresponding to about 570 Myr after the Big Bang. The evidence for a break is strongest in
dust mass and
dust-to-
stellar mass ratio, mostly estimated from JWST NIRSpec spectrophotometric fitting but also partly from sub-mm data. The ultraviolet attenuation measurements are consistent with a transition at the same epoch but do not independently require one. The models are consistent with the onset of efficient interstellar grain growth above a characteristic
metallicity. We interpret the transition near z ~ 8.9 as the emergence of grain-growth-dominated
dust evolution from an earlier regime dominated by
supernova-produced grains. Population III enrichment can modify the earliest chemical-enrichment history but leaves the timing of the
dust transition nearly unchanged and is not required for its emergence.
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All authors Denis Burgarella, Tom J. L. C. Bakx, Raffaella Schneider, Hiddo S. B. Algera, Chloe Aurin, Tim Dewachter, Clarke Esmerian, Luca Graziani, Kirsten Knudsen, Koki Otaki
Quantum Physics · Cross-listed from cs.CC
On the Limits of Quantum Multiparty Simultaneous Communication
Pedro Montealegre, Ivan Rapaport and Jorge Valenzuela
We study the relative power of public randomness and
quantum communication in the multiparty Simultaneous Message Passing (SMP) model. By analyzing a total Boolean function and a relational problem, we establish
polynomial and exponential separations between classical public-coin protocols and
quantum protocols without shared randomness or prior
entanglement. We first introduce XOR Equality, a total Boolean function in which each of $k$ players receives an unrestricted string $x_j\in\{0,1\}^n$, and the referee must decide whether $x_1\oplus\cdots\oplus x_k=0^n$. For $k\ge8$ and worst-case error at most $1/3$, we prove
quantum lower bounds of $\Omega(\min\{n,k^2\})$ on total communication and $\Omega(\min\{n/k,k\})$ on maximum message length. A classical public-coin protocol uses two bits per player with error at most $1/4$. For $n=k^2$ and worst-case error at most $1/3$, we prove that
quantum protocols require maximum message length $\Omega(\sqrt n)$
qubits, whereas two public-coin bits per player suffice. We then turn to relations, for which we obtain exponential separations. Specifically, we study Multiparty Index Coordination, a $k$-player generalization of the two-player relation studied by Gavinsky, Kempe, Regev, and de Wolf (STOC 2006). We prove an unambiguous
quantum lower bound of $\Omega(n^{1-1/k})$ on maximum message length, matched by a classical private-coin protocol. For any fixed error $\varepsilon\in(0,1/8)$, we also prove a bounded-error
quantum lower bound of $\Omega(n^{(k-1)/(k+1)})$ while we show that public-coin protocols solve the relation unambiguously with maximum message length $O(\log n)$, giving exponential separations in both regimes. The implicit constants are independent of $k$, and both
quantum lower bounds become linear when $k\ge c\log n$ for any fixed $c>0$.
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High Energy Physics (Experiment)
Operation and performance of the Probe for Luminosity Measurement at LHCb
F. Alessio, S. Barsuk, C. Beigbeder et al. (+40 more)
The Probe for LUminosity MEasurement (PLUME) detector is a dedicated luminosity monitor at the LHCb interaction point. It is a hodoscope comprising 48 Hamamatsu R760 photomultiplier tubes that detect Cherenkov light produced by particles travelling in the direction opposite to the LHCb spectrometer acceptance. PLUME provides real-time, bunch-by-bunch luminosity measurements during LHCb data taking and serves as the primary detector for controlling the luminosity levelling process at LHCb. In addition, its data are used offline, together with other dedicated counters from LHCb sub-systems, to determine the integrated luminosity delivered to the experiment. This paper reports on the detector's operational performance during the 2024-2026 data-taking period of Run 3. The integrated luminosity recorded by the LHCb experiment in $pp$ collisions at $\sqrt{s} = 13.6$ TeV during this period, as measured by the PLUME online luminosity counters for detector performance monitoring, amounts to $\mathcal{L} = (26.71 \pm 1.07)$ fb$^{-1}$. The luminosity values used in physics analyses are determined separately through dedicated offline calibrations based on van der Meer scans and Beam Gas Imaging techniques, and will be reported in a dedicated publication, as they are beyond the scope of this paper.
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All authors F. Alessio, S. Barsuk, C. Beigbeder, A. Bellavista, O. Bezshyyko, I. Boiaryntseva, C. Bourgeois, A. Boyarintsev, M. Briere, L. Burmistrov, A. Carbone, G. Cavallero, V. Chaumat, S. Cholak, D. Douillet, O. Duarte, P. Durante, F. Ferrari, E. Franzoso, C. Gaspar, L. Golinka-Bezshyyko, L.A. Granado Cardoso, E. Graverini, D. Hohov, G. Iaquaniello, V. Kushnir, R. Matev, P. Mayencourt, V. Mytrochenko, V. Orlov, V. Puill, D. Reynet, P. Robbe, P. Rosier, L. Shchutska, Y. Song, E. Spedicato, L. Toscano, M. van Dijk, A. Villa, G. Vouters, V. Yeroshenko, V. Zhovkovska
High Energy Astrophysical Phenomena
Associating binary black holes with galactic centres using lensed gravitational waves
Laura Uronen, Tian Li, Qiuhan He et al. (+4 more)
Binary black holes (BBHs) have been theorised to form through various different channels, but current LIGO-Virgo-KAGRA (LVK) sky locations make the direct study of formation channels a challenge. Association of strongly lensed BBHs to their hosts has been shown to be possible with current detector networks at upgraded sensitivity and survey
telescopes like Euclid, with localisations that can reach sub-
galactic scales in the source plane. With Hubble Space
Telescope-like high-resolution imaging, we report that strong-
lensing localisation of BBHs allows us to confidently associate the BBH with specific structures within their host
galaxies, specifically,
galactic centres (GCs). We demonstrate that a BBH localised to the GC of the
galaxy can reject light-tracing BBH populations ($p < 5\%$) in a single observation, and in most cases demonstrate high confidence rejection ($p < 1\%$), providing a conservative basis to exclude light-tracing spatial distributions associated with field-like or non-central formation channels. Such association therefore directly supports formation channels confined to GCs, such as active
galactic nuclei and
nuclear stellar clusters.
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All authors Laura Uronen, Tian Li, Qiuhan He, Justin Janquart, Thomas Collett, Léon V.E. Koopmans, Otto Hannuksela
Quantum Physics
Solving wave propagation problems via geometric quantum state preparation on dispersion manifolds
Yakov Solomons, Lee Peleg, Netanel Barel et al. (+3 more)
We present a
quantum algorithm for solving partial differential equations through a linear-system formulation, focusing on wave propagation problems described by the discretized Helmholtz equation in frequency domain. Although
quantum linear-system solvers offer exponential compression of the system degrees of freedom, their runtime complexity is generally governed by the condition number of the discretized operator. Exploiting the analytic structure of the differential operator can provide an alternative to explicit
matrix inversion, as illustrated for the screened Poisson equation through an explicit
quantum circuit. For the Helmholtz equation, however, the inverse operator becomes singular on the dispersion surface $k^2=\omega^2/c^2$, rendering direct
Fourier-space state-preparation methods exponentially inefficient. We address this challenge by directly preparing
quantum states supported on the resonant
manifold and encoding source locations through
Fourier phases. The resulting
algorithm eliminates the exponentially large overhead associated with post-selection on the resonant
manifold, yielding a success probability that depends linearly on the number of sources and is independent of the computational domain size. More generally, our approach applies to
hyperbolic differential equations whose
Fourier-space solutions possess singular support on dispersion
manifolds, recasting their solution as a problem of
geometric quantum state preparation.
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All authors Yakov Solomons, Lee Peleg, Netanel Barel, Jonathan Nemirovsky, Amit Ben-Kish, Yotam Shapira
Physics and Society · Cross-listed from cs.SI
How neighbourhood ideology shapes misinformation belief in densely tied social networks
Soroush Karimi, Marcos Oliveira and Diogo Pacheco
With the rapid spread of news on social media, understanding the propagation of misinformation is becoming increasingly important. One factor that affects individuals' vulnerability to false information is their ideological predisposition. Despite the large number of
agent-based models that focus on social influence as a driver of the spread of false claims, they often fail to explicitly integrate personal ideological biases into belief formation. In this work, we explore how misinformation spreads through the interaction between individuals' ideological biases and social influence. Our model accounts for both the strength of individuals' ideological biases and the extent to which a false claim aligns with their ideology. Social influence modifies the effects of ideological intensity and false claim
alignment through network interactions. Notably, the influence of neighbours' ideological intensity on belief is strongly affected by how well those neighbours are connected to one another. These results highlight the importance of considering both network structure and personal ideological biases when modelling misinformation propagation.
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High Energy Physics (Theory)
Unorientable supersymmetric compactifications of M-theory
Ilarion V. Melnikov and Ruben Minasian
We discuss orbifold compactifications of the type II string, where the orbifold combines a free action on a base
manifold and the $(-1)^{\boldsymbol{F}_{\text{L}}}$
symmetry which acts by -1 on left-moving Ramond sectors. Such backgrounds can preserve minimal supersymmetry and lift to M-theory compactification on smooth unorientable
manifolds.
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Astrophysics of Galaxies
Cosmic-ray electron propagation in the peculiar barred spiral galaxy NGC 2442
Shengtao Wang, Xiaohui Sun, Volker Heesen et al. (+13 more)
Face-on spiral
galaxies offer a favorable geometry for studying
magnetic-field structures and
cosmic-ray (CR) propagation because projection effects and structural overlap are reduced. We investigate
cosmic-ray electron (CRE) transport in the nearby face-on spiral
galaxy NGC 2442 and assess how its environment and
magnetic-field structure influence propagation. We combine
radio continuum (RC) observations from ASKAP at 943 MHz, MeerKAT at 1.28 and 1.7 GHz, and ATCA at 5 GHz with optical H$\alpha$ and infrared data, and compare them with 2D CRE transport simulations. NGC 2442 has a steep integrated RC spectrum, with $\alpha=-0.96\pm0.04$ for the total emission and $\alpha_{\rm nt}=-1.21\pm0.04$ for the synchrotron emission over 408 MHz-5 GHz. A break near 1 GHz indicates substantial radiative aging. Under equipartition, we derive a mean
magnetic-field strength of $10.8\,\mu{\rm G}$. RC-SFR smoothing gives effective CRE propagation lengths of $\sim0.65$-$0.89$ kpc at 943-1700 MHz and $\sim0.44$ kpc at 5 GHz, corresponding to
diffusion coefficients of order $10^{28}\,{\rm cm^2\,s^{-1}}$. We identify a steep-spectrum synchrotron “island” in the southeast, with $\alpha\sim-1.09$ and no clear H$\alpha$, infrared, FUV, or NUV counterpart, indicating that CREs are unlikely to be injected in situ. Our 2D CRPropa simulations show that anisotropic
diffusion along ordered
magnetic fields enables CREs to reach the island more efficiently than isotropic
diffusion. NGC 2442 therefore shows that environmental disturbances and ordered
magnetic fields can strongly regulate CRE propagation in disturbed spiral
galaxies.
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All authors Shengtao Wang, Xiaohui Sun, Volker Heesen, George Heald, Jiangtao Li, Chao-Wei Tsai, Stefan W. Duchesne, Andrew J. Battisti, Yik Ki Ma, Amit Seta, Jun Xu, Naomi McClure-Griffiths, Christopher J. Riseley, Sam Taziaux, Jacco Th. van Loon, Tayyaba Zafar
Instrumentation and Detectors
Optimization and Underground Implementation of the KAPAE Phase II Detector for an Invisible New Particle Search in Positronium Decay
Dongwoo Jeong, Jaeyoung Cho, Doohyeok Lee et al. (+4 more)
The KAPAE Phase II detector was developed to search for invisible decays of positronium as a probe of physics beyond the Standard Model. The detector geometry was optimized with Geant4 simulations, and the scintillation and readout performance were evaluated experimentally. The temperature dependence of the BGO scintillator and several readout configurations were studied to find the operating condition giving the best energy resolution. The background level was then measured both at the surface and underground. At the surface, the positron-gamma coincidence background was of order 1 Hz, with occasional bursts up to about 65 Hz. Underground, it decreased to below about 3 \times 10^{-4} Hz, more than three orders of magnitude lower.
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All authors Dongwoo Jeong, Jaeyoung Cho, Doohyeok Lee, Jaehyeok Kim, HyeoungWoo Park, Yun-Tao Wu, H. J. Kim
Astrophysics of Galaxies
The solar Galactocentric distance and local kinematic parameters from Gaia DR3 using Bottlinger's equations
D. V. Odynets, V. S. Akhmetov and S. I. Denyshchenko
The
solar Galactocentric distance, $R_0$, together with the local kinematic parameters of the Milky Way, provides fundamental constraints on the
Galactic structure and rotation. Their accurate determination has become possible with the hight astrometric precision of
Gaia DR3 catalogue. We determine the Galactocentric distance, the
Solar peculiar motion components $(u_0,v_0,w_0)$, and the local angular velocity of
Galactic rotation, $\omega_0$, using a self-consistent approach based on Bottlinger's equations within a nonlinear least-squares framework. Bottlinger's equations were applied to approximately 13 million luminous
giant stars $(M_G<4)$ selected from
Gaia DR3. The analysis was carried out for two subsamples: a thin disk dominated sample (|z|<0.5 kpc) and a mixed thin and thick disk sample (|z|<1.0 kpc). The kinematic parameters were estimated using a nonlinear generalized least-squares method. We obtained $R_0=8.165\pm0.024$kpc and a local angular velocity of
Galactic rotation $\omega_0=28.477\pm0.002$ km/s/kpc for the thin disk dominated sample. The
Solar peculiar motion components are $(u_0,v_0,w_0)=(9.261\pm0.006,16.593\pm0.008,7.686\pm0.008)$km/s. Including mixed thin and thick disk
stars resulted in a systematic shift in $R_0$, yielding $R_0=8.333\pm0.022$kpc, while the
Solar peculiar motion and local angular velocity remain consistent within uncertainties. The
Galactic kinematic parameters derived are consistent with recent independent determinations. The
Solar peculiar motion parameters and the local angular velocity remain stable for different vertical selections, the recovered Galactocentric distance exhibits a systematic dependence on the adopted
stellar sample, indicating that the vertical structure of the tracer population should be taken into account when determining $R_0$.
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Other Condensed Matter · Cross-listed from cs.CE
Integrated Population Balance and Multiphysics Modeling for Predicting Undesired Agglomeration in Small Molecule Manufacturing
Prakitr Srisuma, Peter Hou, Shashank Venkat Muddu et al. (+3 more)
Agitated filter dryers (AFDs) are a crucial unit operation in small molecule manufacturing that enables simultaneous filtration, washing, and drying of active pharmaceutical ingredients. One of the key challenges in AFDs is associated with undesired agglomeration, where the presence of hard agglomerates results in off-spec products, equipment damage, and additional downstream processing. This article presents a novel mechanistic model that describes the formation of soft and hard agglomerates during agitated filter drying. By integrating population balance and multiphysics modeling, the model can accurately predict the
evolution of the product temperature, moisture content, and particle size distribution, and hence quantify the extend and impact of undesired agglomeration across various operating conditions. Our proposed model-based framework enables the rational design and operation of AFDs for improving the product quality and process reliability.
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All authors Prakitr Srisuma, Peter Hou, Shashank Venkat Muddu, Neda Nazemifard, Allan S. Myerson, Richard D. Braatz
Optics
Surrogate-Assisted Inverse Design and Temperature-Dependent Electrothermal Analysis of an All-Oxide Narrowband Thermophotovoltaic Emitter
Bibekananda Nath, Kawshik Nath and Ahmed Zubair
A narrowband emitter aligning with the bandgap of the underlying
solar cell is essential for improving the spectral efficiency and thermal stability of thermophotovoltaic (TPV) systems. Emitters based on
oxide materials present a promising solution to the optical and mechanical performance degradation of traditional emitters, which employ metal-dielectric structures that experience metal oxidation and structural deterioration at high temperatures. Here, we presented a surrogate-assisted inverse-design framework for a narrowband 1D grating emitter comprising ITO and Al2O3 layers on a sapphire substrate. We performed
Bayesian optimization over the trained ExtraTrees surrogates on a penalty-augmented objective containing a peak-emission constraint (E_peak > 0.90) while minimizing the full width at half maximum (FWHM) and maximizing the fraction of emission concentrated within the selected peak-centered spectral band to acquire a high, narrowband peak emission. The surrogate model was trained using a
dataset of emission spectra obtained from the finite-difference time-domain (FDTD) by systematically varying the layers' thicknesses and the structure's period as the input features, and the narrowband emission's figure of merit (FOM) ((E_peak), wavelength of peak emission (_peak), FWHM, in-band fraction (f_in) for determining the amount of emission outside the peak band, and concentration of peak emission near the peak) was used as the prediction target. The resulting set of predictions for the optimized structure was further validated using the FDTD method.
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General Relativity and Quantum Cosmology
Pulsar Timing Response and Spatial Correlations of Shear Modes in Torsionless Palatini Spacetime
Tian-Shi Li, Yu-Mei Wu and Chang Liu
In the nanohertz band, spatial correlations between
pulsar timing residuals provide a key observable for characterizing
stochastic gravitational-wave backgrounds and probing their polarization content. In torsionless Palatini spacetime, nonmetricity can generate two additional shear modes, referred to as the shear-$x$ and shear-$y$ modes. In this work, we investigate the
pulsar timing response produced by the shear-induced motions of the emitting
pulsar and the receiving Earth. Assuming that the electromagnetic field is minimally coupled to the physical metric and that the Earth and
pulsar possess non-negligible effective hypermomentum responses, we derive the single-
pulsar redshift, the frequency-domain two-point correlation function, and the corresponding spatial correlation. For a stationary and isotropic
stochastic shear background, the normalized overlap reduction function (ORF) for distinct
pulsars reduces in the short-wavelength limit to the pure dipolar form $\Gamma_{ab}^{\mathrm{sh}}(\zeta)=\cos\zeta$, where $\zeta$ is the angular separation between the two
pulsars. The same dipolar correlation can also be produced by isotropic
Solar System ephemeris errors, leading to a spatial degeneracy between the two signals. This degeneracy highlights the importance of information beyond the angular correlation for identifying Palatini shear signatures in PTA data.
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Quantum Physics
An analysis of iterative refinement for quantum linear system solvers
Adrian Harkness, Mohammadhossein Mohammadisiahroudi, Brandon Augustino et al. (+2 more)
We present and analyze an iterative refinement (IR) framework for improving the precision dependence of
algorithms that combine a
quantum linear system
algorithm (QLSA) with
quantum state
tomography. Existing QLSAs achieve polylogarithmic dependence on the inverse error tolerance to prepare a
quantum state encoding the solution, but extracting a classical description of such a state via
tomography typically introduces a
polynomial dependence on the target precision. To retain polylogarithmic dependence in the inverse error tolerance throughout the entire process, we develop an IR scheme that solves a sequence of related linear systems to progressively refine the solution while requiring only fixed-precision
quantum subroutines, finally obtaining a classical description of a high-precision solution. We analyze the proposed framework under three input models:
quantum-read/classical-write RAM (QRAM), linear combinations of
unitaries (LCU), and sparse-access oracles. We evaluate the proposed scheme through numerical experiments on both
quantum simulators and real
quantum hardware. The results demonstrate that iterative refinement efficiently improves the precision of the solution and exhibits robustness to hardware noise.
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All authors Adrian Harkness, Mohammadhossein Mohammadisiahroudi, Brandon Augustino, Giacomo Nannicini, Tamás Terlaky
Geophysics
Holistic law of aftershocks
A.V. Guglielmi
The paper is devoted to the phenomenological theory of aftershocks occurring in the source of a tectonic earthquake following the main shock. The theory was developed by the author jointly with A.D. Zavyalov and O.D. Zotov during the course of a long-term study of aftershocks. The theory is based on the concepts of source deactivation and the source's proper time. The holistic law governing the decay of aftershock activity over proper time follows from the theory. The damping decrement is equal to the source deactivation coefficient. The main focus of this paper is the analysis of the logical structure of the theory. The paper also contains a brief description of the experimental results obtained using the theory. Keywords: earthquake source, aftershocks, Omori's law, Utsu's law, deactivation coefficient, proper time, underground clock, foreshock convergence, aftershock divergence.
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Soft Condensed Matter
Characterizing particle rearrangements in sheared highly polydisperse materials
Waad Paliwal and Eric R. Weeks
We compare three particle-scale measures of rearrangement in highly polydisperse materials under driven flow: (a) nonaffine motion defined relative to the time-averaged mean flow, (b) changes in nearest-neighbor connectivity, and (c) $D^2_{\min}$, which measures nonaffine motion relative to an affine deformation fitted locally in space and time [Falk and Langer, Phys. Rev. E 57, 7192 (1998)]. We apply these measures to previously published two-dimensional simulations [Jiang, Sussman, and Weeks, Phys. Rev. E 108, 054605 (2023)] and granular-flow experiments [Illing and Weeks, Phys. Rev. E 111, 045422 (2025)] with polydispersities up to $\delta\approx0.50$. Changes in connectivity and $D^2_{\min}$ both require a definition of neighboring particles, making the choice of neighborhood nontrivial in highly polydisperse systems. For detecting changes in connectivity, we recommend radical Delaunay triangulation, which provides a size-aware topological definition of neighbors. For calculating $D^2_{\min}$, we recommend a size-aware pairwise cutoff distance method. We further show that changing the neighborhood definition can reverse the apparent dependence of $D^2_{\min}$ on particle size in experimental data. Thus, trends in $D^2_{\min}$ cannot be interpreted independently of the neighborhood used to calculate it. Overall, the three measures presented provide complementary information about rearrangements in highly polydisperse systems.
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Computational Physics · Cross-listed from math.NA
Order elevation of directly self-starting sub-step implicit integrators for transient dynamics
Jinze Li, Yaokun Liu, Kewei Chen et al. (+2 more)
Directly self-starting implicit methods are attractive for transient analysis because they avoid auxiliary starting procedures while retaining the original first- or second-order governing equations. However, most existing formulations usually fix the last sub-step at the end of each time interval, which restricts the attainable order. This study develops a generalized $s$-sub-step implicit framework by releasing this constraint and treating all sub-step locations as design variables. The resulting methods admit a unified Runge–Kutta representation for both first- and second-order transient systems and preserve identical effective
matrices over all sub-steps. Accuracy conditions are derived by simultaneously matching the numerical amplification factor and load operator, thereby accounting for both homogeneous and forced responses. For $s=1,~\cdots,~6$, two complementary families are obtained: $s$th-order members with user-controllable high-frequency numerical dissipation and adjustable sub-step locations, and $(s+1)$th-order members obtained by selecting the sub-step locations, with fixed dissipation. The latter reach up to seventh-order accuracy without increasing the number of sub-steps, although some high-order members are $A(\alpha)$-stable with stability angles extremely close to $90^\circ$. Analytical amplitude and phase errors further reveal parity-dependent superconvergence in undamped systems, and appropriate parameter selections can substantially increase either phase or amplitude accuracy beyond the formal order. Numerical
benchmarks confirm the predicted convergence orders and the controllable suppression of spurious high-frequency responses.
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All authors Jinze Li, Yaokun Liu, Kewei Chen, Hua Li, Kaiping Yu
Fluid Dynamics
A stochastic modeling framework to generate 2-D rough-wall high-Reynolds-number turbulent boundary layers
Roozbeh Ehsani and Michele Guala
Atmospheric surface layer flows are computationally challenging, predominantly due to surface roughness and the high Reynolds number, both of which demand exceptionally high spatial resolution in the near-surface region. We have developed a 2-D
stochastic-based model for the generation and the streamwise concatenation of instantaneous, step-like velocity profiles featuring key elements of wall turbulent flows, i.e., uniform momentum zones (UMZ) and shear layers (Ehsani et al. 2024a,b), and
vortices (Ehsani et al. 2026). The model is extended herein to the top of the logarithmic layer to reproduce the high-Reynolds-number, rough-wall, turbulent boundary layer measured by Saddoughi and Veeravalli(2000), without the support of a UMZ
dataset, using only a handful of critical flow parameters: the Taylor microscale {\lambda}T, the boundary layer height {\delta}, the friction velocity u{\tau}, and the aerodynamic roughness length z0. The primary challenge lies in the integration of the
stochastic model with the scaled distributions of the UMZ and
vortex characteristics. The resulting statistical moments, energy spectra, and structure functions are compared against the experimental results. The validated code is made available in a GitHub repository.
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Optics
Optical design for implementing non-collinear circularly polarized high harmonic generation in an enhancement cavity
Pranshu Dave, Thierry Auguste, Olivier Girard et al. (+2 more)
We introduce an original optical cavity design intended to efficiently output-couple extreme ultraviolet (XUV) light produced via cavity-enhanced high harmonic generation (CE-HHG). It supports the amplification of oppositely circularly polarized modes, crossing with a small angle in the high finesse cavity, where circularly polarized HHG scheme (NCP-HHG) will be implemented. We present an analytical model, numerical simulations, and experimental results obtained with a low-power continuous (CW)
laser, demonstrating the strong potential of the cavity as an efficient XUV output coupling method. In particular, it is well suited for producing the 7th harmonic (H7) from an Ytterbium frequency comb at 8.4 eV, which is of particular interest for precision
nuclear spectroscopy of Thorium.
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All authors Pranshu Dave, Thierry Auguste, Olivier Girard, Thierry Ruchon, David Bresteau
Statistical Mechanics
Italian Business-to-Business Invoicing Data: A Network Analysis
Valerio Astuti and Daniele Piras
We present a comprehensive description of the network of Italian Business-to-Business commercial relationships, based on the universe of electronic invoices collected by the Italian Tax Office. The firm-to-firm detail of the data is exploited to describe the distribution of the numbers of buyers (customers) and sellers (suppliers) per firm, the centrality of each firm in the production network, and the average distance between firms. We characterize for the first time the firm-to-firm network describing the Italian production system, and present its geographic and sectoral breakdown. The analysis reveals heavy tailed distributions for the numbers of buyers and sellers per firm, implying a scale-free structure of the network. The distributions of centrality values display heavy tails as well, indicating a strong concentration of importance in a relatively small number of firms. We estimate the tail exponents for all these distributions, finding in all cases lower exponents for downstream (buyer-side) distributions than for the upstream (seller-side) ones.
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General Relativity and Quantum Cosmology
Testing Source Dependence in Gravitational-Wave Tests of General Relativity with Mutual Information
Yi-Fan Wang
Phenomenological deviation parameters used in gravitational-wave tests of general relativity need not represent universal fundamental properties of the sources. Instead, a deviation parameter can be a derived quantity that depends on source properties. Apparent violations of general relativity arising from waveform systematics or data-quality issues can also depend on source properties. In addition to diagnosing individual events, it is helpful to identify systematic trends at the population level. We introduce a nonparametric framework that uses mutual information to test whether the deviations depend on source properties. We validate the framework using simulations with massive graviton waveforms. Assuming we do not have prior knowledge of the underlying theory, massive graviton effects can be captured by a parameterized post-Einstein coefficient that is expected to depend on the luminosity distance and source mass. The results show that the mass and distance dependencies become clear for graviton masses of $\geq 1\times10^{-22}\,\mathrm{eV}$ at detector sensitivities representative of the current fourth observing run, while the controlled general relativity simulations yield null results. We then analyze public real-data products for tests of general relativity from GWTC-4.0 and 4-OGC, including phenomenological parameterized tests, modified dispersion tests, and parity violation tests. The phenomenological deviation parameters have tentative correlations with effective
spin, and correlations of modified-dispersion or parity-violation parameters with source mass are visible. These results demonstrate that catalog-level dependence can identify patterns and thus be used to diagnose the origin of deviations in testing general relativity. The framework therefore complements single-event analyses and parameterized hierarchical population tests.
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Quantum Physics
Information capacity of quantum statistics: Fock-state tests of a discrete binary-sequence model on cloud photonic quantum processors
Chiran Wijesundara, Octavia T. Volpe, Dejan Stojkovic et al. (+2 more)
Our central premise is that
quantum mechanics may be the statistical limit of a more fundamental discrete theory: any such theory equips a physical system with a finite information capacity, and its departure from
quantum statistics is controlled by how much of that capacity the system uses. We show that commercial cloud photonic
quantum processors have reached the precision required to bound this capacity from below, using the binary-sequence model of Powers et al. as the concrete test theory: outcome probabilities arise from counting discrete sequences of length $n$,
quantum mechanics is recovered as $n \to \infty$, and $n$ measures the information capacity of the register behind a prepared state.
Photon Fock states $|1\rangle$, $|1,1\rangle$, heralded $|2\rangle$, and cascaded beam-splitter pairs are measured on programmable interferometers with dominant systematics determined in situ. The model's composition-consistent parametrization, singled out by requiring that rotations compose, recovers
quantum mechanics with deviations $1.24/n$; a random-effects likelihood analysis calibrated by parametric bootstrap excludes all $n \le 100$: the information capacity of the register carrying the two-
photon state, if finite, exceeds $10^2$. Cascaded beam splitters test the composition law directly: the data are split-invariant, excluding naive count composition at $8\sigma$ and confirming the interference-sign rule. Model-independently, curve-averaged deviations from the
quantum partition law larger than $2.3\times10^{-2}$ are excluded at 95% CL, and the originally published linear parametrization is excluded outright. Because the compilation offset is frozen per
circuit it is calibratable, opening the $10^{-3}$ floor ($n \sim 10^3$) to current hardware: cloud photonic processors are quantitative instruments for
quantum foundations, and information capacity an experimentally boundable quantity.
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All authors Chiran Wijesundara, Octavia T. Volpe, Dejan Stojkovic, Herbert Fotso, Tim Thomay
High Energy Astrophysical Phenomena
Anisotropic wind in tidal disruption events
Paola Martire, Elena Maria Rossi, Nicholas Chamberlain Stone et al. (+2 more)
Over the coming years, the number of
tidal disruption events (TDEs) is expected to substantially increase with observations from the Vera Rubin Observatory (g and r band) and ULTRASAT (near UV) wide-field surveys. These future samples have great promise to characterize the bottom end of the massive black hole mass function, but existing detections of intermediate mass black hole TDEs are primarily in X-rays, leaving their optical/UV emission largely unexplored. We present a time- and angle-dependent analysis of the
outflow produced by dissipation near pericentre in a three-dimensional end-to-end radiation-hydrodynamics simulation of a TDE by a $10^4 M_\odot$ black hole with realistic parameters, run with the code RICH. We find that
outflow anisotropy produces viewing-angle-dependent observables. Towards the poles and the pericentre region, mass-loss rates are low and bolometric luminosities reach $\sim2$–$3$ times the Eddington luminosity. Towards the stream, the properties show a stronger dependence on latitude: the mass-loss rate increases and the bolometric luminosity decreases as the line of sight approaches the orbital plane. These denser regions favour H$\alpha$ and H$\beta$ emission. Despite these variations, all viewing directions show a common spectral
evolution, with an initial soft X-ray
flare followed (around $1.25t_{\rm fb}\approx3$~days) by the reprocessing of shock-powered emission into the UV and optical bands. Although the optical/UV luminosities we predict for this TDE are likely too dim for past surveys (e.g. ASAS-SN, ZTF), they are within the detection capabilities of LSST and ULTRASAT to horizons of $\sim 790$ and $\sim 340$ Mpc, respectively, for the brightest viewing directions.
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All authors Paola Martire, Elena Maria Rossi, Nicholas Chamberlain Stone, Elad Steinberg, Itamar Giron
Superconductivity
Linear and nonlinear Edelstein effects in Rashba superconductors
Hikaru Ueki and Youichi Yanase
We formulate a quasiclassical theory of the Edelstein effect in
superconductors that incorporates both intraband and interband contributions. To describe the interband contribution, which is absent from the conventional leading-order quasiclassical formulation, we derive augmented Eilenberger equations in the presence of antisymmetric
spin-orbit coupling. The intraband contribution is evaluated using multiband Eilenberger equations. We apply these formulations to supercurrent-induced surface
spin magnetization in $s$-wave Rashba
superconductors and investigate its dependence on temperature, distance from the surface,
spin-orbit coupling strength, and supercurrent. The intraband contribution originates from a supercurrent-induced asymmetry of quasiparticles with opposite momenta and
spin polarizations, whereas the interband contribution arises from the anomalous-velocity term generated by the momentum derivative of the Rashba
spin-orbit potential. In the helicity basis, this anomalous-velocity term is expressed in terms of the Berry connection associated with the momentum dependence of the Rashba eigenstates. The intraband contribution increases linearly with the
spin-orbit coupling strength, whereas the interband contribution exhibits a nonmonotonic dependence and is maximized when the Rashba
spin splitting is comparable to the superconducting gap. Moreover, within the clean $s$-wave Rashba model considered here, we find that the nonlinear dependence of magnetization on the supercurrent arises solely from the interband contribution. Thus, although the intraband contribution dominates the linear Edelstein effect, the nonlinear Edelstein effect can serve as a useful probe of the interband contribution originating from
quantum geometry.
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Quantum Physics
Finite-Particle Quantum Reduction of Thermodynamic Irreversibility
Borhan Ahmadi
Thermodynamics is useful because it lets us predict and control complex systems from a few accessible quantities when microscopic reconstruction is impractical. We ask whether this operational reduction can be less costly in a finite
quantum system than in a matched classical one. We compare a few-
boson Bose–Hubbard chain with its number-conserving classical-field counterpart under the same driving and the same coarse spatial record. The
quantum system relaxes more in the observed particle distribution, yet the retained mean energy resolves more of the microscopic structure hidden by that record, leaving less information unusable and smaller
entropy generation. We then close the process into a heat-engine cycle whose controls use only the measured mean energy and spatial record, not full state
tomography; at matched thermal resources, the smaller
entropy generation gives more work and higher efficiency. The advantage fades as the particle number grows toward the classical-field regime.
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