Disordered Systems and Neural Networks
Storing Infinite Dynamical Attractors in Nonreciprocal Associative Neural Networks
Miguel Aguilera and Daniele De Martino
We develop a dynamical mean-field theory for nonreciprocal associative networks that store an extensive number of dynamical attractors, from limit cycles to strange attractors. Using a path integral calculation under quenched disorder, we derive self-consistent dynamical mean-field equations for pattern overlaps, autocorrelations and response functions.
Memory retrieval capacity is governed by the spectral structure of the coupling
matrices encoding stored patterns. When their
eigenvalues are coherently aligned, retarded self-interactions and quenched noise feed back destructively: at zero eigenphase (fixed point attractors) the classical
equilibrium capacity bound is recovered, while for limit cycles
retrieval collapses far below it. In contrast, for uniformly distributed eigenphases, retarded self-interactions and much of the quenched noise cancels, reducing the dynamics to an effective single-
spin process and amplifying capacity substantially. We validate the theory against microscopic simulations for limit-cycle and chaotic attractors, identifying
eigenvalue decoherence as the mechanism enabling enhanced storage of dynamical
memories.
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Quantum Physics
Phase estimation in spontaneous nonlinear interferometry for enhanced quantum imaging
Jonas L. Moos, Cristofero Oglialoro, Enno Giese et al. (+1 more)
Bicolor
quantum imaging can reach, in principle, phase supersensitivity approaching the Heisenberg limit using squeezed light from high-gain parametric down-conversion, but established
quantum-imaging setups typically operate in the low-gain, spontaneous regime, where such scaling is inaccessible. Here, we show experimentally and theoretically that a symmetric nonlinear interferometer, even in the spontaneous regime, retains a phase-sensitivity advantage over configurations where
entanglement is not exploited as a
quantum-metrological resource, although the achievable phase sensitivity remains shot-noise-limited. This advantage appears as a shift of the optimal working point toward the dark fringe, the low-gain signature of the mechanism underlying high-gain supersensitivity. We derive design choices for phase-optimized nonlinear interferometers accordingly, favoring configurations that exploit
entanglement as a metrological resource and specifying their optimal operating point.
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All authors Jonas L. Moos, Cristofero Oglialoro, Enno Giese, Markus Gräfe
Pattern Formation and Solitons
Novel Transition Mechanisms of Vector Localized Waves Induced by the Fourth-Order Effect
Rong Han, Muchen Dong and Lei Wang
We investigate novel vector localized wave solutions in the coupled Lakshmanan-Porsezian-Daniel equa?tions, which describe the dynamics of the Heisenberg
ferromagnetic spin chain. We present Tajiri-Watanabe breathers, rogue waves and resonant modes in both the degenerate and non-degenerate regions, together with the degenerate beating
solitons. The fourth-order effect induces state transitions in both regions. In particular, the degenerate breathers can be transformed into
solitons, whereas such transitions are absent in the coupled Hirota equations. Moreover, beating
solitons can be converted into stable
solitons only in the degenerate region, the phenomena not found in the Manakov system. We further uncover the state transitions of the resonant modes and derive the corresponding transition conditions for each branch. We derive the physical spectra and subsequently identify the state transition conditions in the spectral domain for both the degenerate and non-degenerate cases. These spectra provide an additional characterization of the transition dynamics. Finally, direct numerical simulations are performed to verify the validity of the exact solutions.
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Earth and Planetary Astrophysics
A semi-analytical Ring-Arc model for Plutino perturbations
Yue Chen and Jian Li
Neptune's 2:3 mean motion resonance induces an asymmetric spatial distribution of Plutinos. We previously proposed a 9000-point-mass arc model that successfully captures the resulting influence on planetary ephemerides. However, integrating thousands of point masses involves significant computational cost. In this paper, to more efficiently simulate the total perturbation of Plutinos, we develop a semi-analytical Ring-Arc model described by gravitational potentials. This model consists of an outer ring and two inner arcs, representing the resonant spatial distribution of Plutinos. The model parameters are derived from observed Plutinos and theoretical sampling, yielding consistent structures. Numerical simulations show that the perturbations on the Sun-Neptune and Sun-Saturn distances from the semi-analytical Ring-Arc model agree with those from the 9000-point-mass arc model within 4% over 50 years, while outperforming a simple ring model in comparison with the bias-corrected Plutino population. Our semi-analytical approach preserves the dynamical characteristics while significantly enhancing computational efficiency, offering a state-of-the-art tool for ephemeris modelling.
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Statistical Mechanics
Emergent Equilibrium Structure Along a Critical Cluster Recursion
Shuo Wei, Abbas Ali Saberi and Youjin Deng
Critical universality does not determine the microscopic conditional structure of a probability measure. We study a bicolored cluster recursion constrained to remain critical at every generation, with no
equilibrium spin measure or fixed coupling imposed. In both two and three dimensions, the resulting history-dependent sequence develops a common Ising/Fortuin–Kasteleyn (FK) compatibility structure: the second-shell dependence of a one-site conditional law is strongly suppressed, nearest-neighbor effective couplings move progressively toward one another near the critical Ising value, and cluster and interface observables organize around the corresponding FK geometry. An exact cluster-coloring factorization singles out $q=2$ as the point where the residual connectivity weight disappears from the two-color
spin marginal. Thus
equilibrium-compatible conditional structure can emerge along a trajectory that remains critical throughout.
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Mesoscale and Nanoscale Physics
Unveiling the Scaling Potential of Drain Merge through Active (DMtA) in CFETs: Breaking the Super-Via Bottlenecks and Unlocking New PPA Boosters
Jingru Jiang, Haoran Lu, Kairong Guo et al. (+11 more)
Drain merge (DM), a super via vertically connecting the common S/D terminals of stacked n/pFETs in Complementary FETs (CFETs), blocks further parasitic optimization and
cell scaling. For the first time, this work systematically investigates the state-of-the-art Drain Merge through Active (DMtA), a revolutionary technology reported recently with the DM embedded in the active region, through a comprehensive DTCO framework spanning process integration, contact-configuration-dependent (CTCD) compact modeling, standardcell design, RO evaluation and block-level PPA
benchmark on a 32-bit RISC-V Ibex core. By reducing DM parasitics and enabling DM-width optimization, DMtA improves RO frequency by 11.7% over its conventional Drain Merge through field (DMtF) counterpart. Active widening and Area Borrowing, the latter first reported in [8] and exploiting spatial slack in adjacent
cells to further enlarge the nanosheet width (WNS), increase the maximum Ibex-core frequency by up to 34.8%. More importantly, DMtA also enables the once GAA-exclusive Hyper-
cells on CFETs by merging the active regions across adjacent
cell rows, providing a further 8.7% frequency gain. A post-routing floating-output-pin-aware optimization further removes redundant S/D contacts (CTs) and reduces power by 5.3%. Finally, DMtA facilitates more area-efficient 2.5T
cell scaling by preserving single-row
cell compatibility, reducing post-PR core area by 25.7%.
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All authors Jingru Jiang, Haoran Lu, Kairong Guo, Yibo Zhang, Yifei Chen, Wanyue Peng, Yu Liu, Jiacheng Sun, Xiaoyan Xu, Ming Li, Yibo Lin, Runsheng Wang, Ru Huang, Heng Wu
Fluid Dynamics · Cross-listed from math.NA
A new formulation of Discontinuous Galerkin method for interface capturing approaches
W. Herri, K. Benmoussa, R. Bouydou et al. (+1 more)
In computational fluid dynamics, the numerical simulation of free-surface flows using interface capturing approaches (level set, pseudo-concentration) requires accurate resolution of a transport equation. In the present work, this equation is solved using a new formulation of the Lesaint–Raviart discontinuous Galerkin method, which is particularly suitable for problems without inflow boundaries. The motion is described by the incompressible Navier–Stokes equations with surface tension, discretized using the standard $P2-P1$ Taylor–Hood finite element method in space. Surface tension effects are represented using the so-called Continuum Surface Force model. Finally, the proposed approach is implemented and tested on several
benchmarks, including the single rising bubble and the Rayleigh–Taylor instability.
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All authors W. Herri, K. Benmoussa, R. Bouydou, D. Yakoubi
General Relativity and Quantum Cosmology
Exact Cancellation of Horizon Modes in Kerr Ringdown
Kei-ichiro Kubota, Yusuke Manita, Hayato Motohashi et al. (+1 more)
Ringdown gravitational waves probe black hole spacetimes via quasinormal modes (QNMs). Recent studies have reported oscillatory features in QNM-filtered waveforms, and have led to conflicting interpretations as to whether they represent a near-horizon "direct wave". Reexamining a particle plunging into a Kerr black hole, we show that the saddle-point approximation underlying the proposed interpretation fails near the horizon. Our exact analysis reveals that every source-induced horizon-mode pole is canceled by an infinite tower of Matsubara zeros, independently of orbital and black-hole parameters. The first four stages of this sequential screening are also confirmed by time-domain numerical integration. Thus, within the near-horizon perturbative framework, source-induced horizon-mode signals do not survive at late times.
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All authors Kei-ichiro Kubota, Yusuke Manita, Hayato Motohashi, Daiki Watarai
Chemical Physics
Strong Evidence for Formation of Hydroxyl Anion via 2-Particle-1-Hole Feshbach Resonances
Siddique Ali, Meenakshi Rana, Soumya Ghosh et al. (+3 more)
This study investigates the formation of the hydroxyl anion (OH$^-$) via dissociative electron attachment in 2-propanol as a model system for studying both organic and inorganic molecules. Using high-level CAP-EOM-EA-CCSD calculations and advanced ToF mass spectrometry, we demonstrate that OH$^-$ formation at electron energies between 7 and 11 eV is dominated by two-particle-one-hole (2p-1h) Feshbach resonances. The potential-energy curves reveal a dense
manifold of anionic states coupled through numerous avoided crossings, facilitating nonadiabatic population transfer during C-OH bond dissociation. Survival-probability analysis identifies a subset of six long-lived resonances that persist long enough to drive fragmentation, with states 25 and 28 acting as primary drivers by funneling the attached electron into the localized $\sigma^*(\mathrm{C{-}OH})$ antibonding orbital. These theoretical predictions are confirmed by experimental observations of a prominent OH$^-$ yield peaking at 8.6 eV, supporting a site-specific fragmentation mechanism that generalizes to the broader class of molecules.
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All authors Siddique Ali, Meenakshi Rana, Soumya Ghosh, Narayan Kundu, Aryya Ghosh, Dhananjay Nandi
General Relativity and Quantum Cosmology
Darboux Isospectrality Constraints on Quasinormal Modes Deformed by Bumps
Zhen-Xiao Zhang, Chen Lan and Yan-Gang Miao
A localized Gaussian or Pöschl-Teller bump is widely used to probe the sensitivity of Schwarzschild quasinormal modes, where it is typically added to both the Regge-Wheeler and Zerilli potentials. We show that such an additive prescription is generically incompatible with the Darboux transformation connecting the two parity sectors. The reason is that such a transformation restricts a parity-blind bump to a fixed family of bumps with an unavoidable $r^{-2}$ tail, excluding any Gaussian or Pöschl-Teller profile with arbitrary amplitude, center, or width in the additive prescription. We give the complete classification of Darboux-admissible axial and polar pairs of bumps and propose two consistent scenarios: Darboux generator prescription in which a Gaussian or Pöschl-Teller profile is retained as a generator of the bump pair rather than as the bump itself, and Riccati completion prescription in which a Gaussian or Pöschl-Teller profile is regarded as one of the bump pair and its partner will be solved from the Riccati equation. Our frequency-domain calculations confirm that a finite and spurious axial-polar splitting of quasinormal modes will be produced if the Darboux-consistent scenarios are absent, while the centroid shift of the fundamental mode is nearly unchanged.
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Materials Science
Modular and Cost-effective Scanning Photocurrent Microscopy System for Sub-micron characterization of 2D optoelectronic devices
Nuria Jiménez-Arévalo, Dan Zheng, Yong Xie et al. (+8 more)
Scanning photocurrent microscopy (SPCM) is a powerful technique for probing local optoelectronic phenomena in 2D semiconducting devices. However, commercial setups remain costly, complex and often lack flexibility and adaptability. In this work, we present a home-built SPCM platform built around the retrofitting of a conventional metallographic microscope by coupling it with different light sources (single-mode fiber-coupled
lasers and multimode fiber-coupled high-power LEDs), a motorized XY stage, a digital camera and an electronic readout module. This system enables simultaneous acquisition of photocurrent and reflection intensity maps, requiring minimal modifications of the microscope. We reached sub-micron spatial resolution and high imaging fidelity by correlating photocurrent maps with reflection maps, optical micrographs and AFM topography data on different devices fabricated with different materials (InSe, MoS2, WSe2, Gr), on different substrates (Si/SiO2, compact disk). This work provides a reliable, accessible and reproducible high-performance SPCM platform that can be easily implemented in most laboratories for microscale optoelectronic characterization of 2D devices.
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All authors Nuria Jiménez-Arévalo, Dan Zheng, Yong Xie, Peng Cheng, Yi Liu, Rafael Luque Merino, Haiwen Yu, Tao Wang, Riccardo Frisenda, Andres Castellanos-Gomez, Qinghua Zhao
Earth and Planetary Astrophysics
That's no moon: Exomoon survival and detection limitations
Alicia Pérez-Rodrigo and Isabel Rebollido
While moons are ubiquitous in the
Solar System, exomoons have not yet been unambiguously confirmed despite the discov- ery of over 5,600
exoplanets. We investigated the reasons for this lack of detections by reviewing high-impact literature searches, assessing dynamical stability and detectability constraints, and comparing these with the moon population in the
Solar System. We compiled a homogeneous catalogue of 24 proposed exomoon candidates, including
stellar, planetary, and inferred lunar parameters. For each case we applied Hill, Roche, and Laplace stability criteria and estimated detectability limits for current and forth- coming instruments. In addition, we tested 6038 confirmed
exoplanets against the same stability and mission-specific observational filters for a given range of moon parameters. A large fraction of the potential exomoon candidates investigated in the literature are either inconsistent with long-term stability or produce signals below Kepler sensitivity. Only 8 of the 13 candidates meet at least one of the stability criteria. Our extended analysis highlights 27 promising targets for exomoon searches with PLATO, while moons with
Solar-System-like properties remain below current thresholds. The lack of exomoon detections is likely due to a combination of the inefficient formation of stable massive moons and limited instrumental sensitivity. Other processes, such as early moon loss during planetary migration or
giant impacts, may also influence moon survival. Future searches should prioritise systems that combine long-term dynamical stability with favourable observational conditions for next-generation photometric and astrometric facilities.
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Quantum Physics
Symmetry-resolved tree tensor network analysis of Bell-state discrimination with ancilla-assisted passive linear optics
Anand Kumar, Wojciech Roga, Devendra Kumar Mishra et al. (+1 more)
Ancillary
photons allow passive linear-optical Bell-state discrimination to exceed the one-half probability of success limit achievable with
vacuum auxiliary modes. For a fixed analyzer and ancillary resource, the discrimination probability is determined by the
photon-counting patterns that occur uniquely for each Bell input. We develop a
photon-number-resolved tree tensor network method for evaluating these detector supports in recursively structured analyzers.
Photon-number conservation and mode
symmetries separate most of the Bell-state outputs before the remaining detector support is examined. We establish a tree tensor network based construction to evaluate the remaining support without need of recalling all relevant
photon detector patterns separately. We apply the method to recursive, product, and asymmetric ancillary states with up to $32$ optical modes and reproduce known analytical and literature
benchmarks. For factorized ancillary resources with fixed
photon numbers in halves of the analyzer and the
symmetry property used in our analysis, we also derive an exact composition relation; for reflected asymmetric pairings the success probability is the arithmetic mean of the corresponding symmetric configurations. The complete enumeration for smaller systems, permanent-based amplitude calculations, and independent evaluations provide additional checks of the numerical results.
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All authors Anand Kumar, Wojciech Roga, Devendra Kumar Mishra, Masahiro Takeoka
Optics
Planar metal-semiconductor Yagi-Uda type antennas for tunable narrow-linewidth quantum dot emitters
Ievgen Brytavskyi, Andreas Kitzmüller, Santanu Manna et al. (+13 more)
Tunable photonic architectures that improve the extraction efficiency of light from embedded epitaxial
quantum dots across a wide spectral range are key enablers for developing bright sources of single and indistinguishable
photons. In this study, we experimentally demonstrate planar multilayer
antenna structures consisting of epitaxially grown AlGaAs and InGaAs membranes containing
quantum dots sandwiched between metallic Au (or Ag) reflector and director layers together with Al$_2$O$_3$ spacer layers. We show that the linewidths and fine-structure splitting of the neutral
exciton emission remain comparable to those measured in the corresponding unprocessed samples, demonstrating that the fabrication process preserves the optical quality of the emitters. In addition to broadband operation, we demonstrate that the planar architecture is compatible with electrical tuning via integrated diode structures, and strain tuning using piezoelectric actuators. In spite of limitations related to optical losses in the ultrathin metallic layers, the demonstrated fabrication simplicity, scalability, and compatibility with tunable
quantum emitters establish planar
antennas as a promising platform for solid-state
quantum photonic devices.
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All authors Ievgen Brytavskyi, Andreas Kitzmüller, Santanu Manna, Gabriel Undeutsch, Christian Weidinger, Thomas Oberleitner, Ailton J. Garcia, Jr., Saimon Filipe Covre da Silva, Josef Resl, Raphael Joos, Robert Sittig, Michael Jetter, Simone L. Portalupi, Peter Michler, Armando Rastelli
Mathematical Physics · Cross-listed from math.PR
Christoffel transform and symplectic skew Howe duality
Anton Nazarov, Pavel Nikitin and Anton Selemenchuk
For a symmetric weight $w(x)$ on a finite discrete
lattice and its Christoffel transforms $x^{2}w(x),x^{2}(x^{2}w(x)),\dots$, we prove that, at each Christoffel step, the conjugated projection associated with the transformed Christoffel–Darboux kernel differs from the original orthogonal projection by a rank-one operator on the subspace of functions vanishing at the origin. This provides a general mechanism for transferring local asymptotic results from an orthogonal
polynomial ensemble to its Christoffel-transformed counterpart as the
lattice size tends to infinity. As a main application, we study local fluctuations of random Young diagrams arising from skew $(\mathrm{Sp}_{2n},\mathrm{Sp}_{2k})$ Howe duality. The corresponding particle ensemble is obtained from the Krawtchouk orthogonal
polynomial ensemble on a quadratic
lattice by a Christoffel transform. We identify four asymptotic regimes of local fluctuations in the limit $n,k\to\infty$ with $n/k\to c\in(0,\infty)$. Besides the universal bulk fluctuations governed by the discrete sine kernel and universal Airy fluctuations at the right edge of the limit shape, we obtain the discrete Hermite kernel in the critical regime $(k-n)/\sqrt{n+k}\longrightarrow r\in\mathbb{R}$, and the discrete hard-wall sine kernel at the left corner.
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Mathematical Physics
Big Crunch on Julia and Anti-Julia Sets in the Integrable Limit
Masatomi Iizawa, Satoru Saito, Yasuhito Narita et al. (+3 more)
The Julia set is defined by the closure of repelling periodic points in chaotic systems. Why does this structure not appear in integrable systems? In this paper, we address this question by demonstrating the existence of the closure of divergences of the periodic equations, which we designate as the "anti-Julia set." We also call the sets before taking the closures the pre-Julia and pre-anti-Julia sets, respectively. We illustrate the transition mechanism by considering a complex map that interpolates between integrable and non-integrable dynamics, by introducing a real deformation parameter $a$. For $0<a\le 1/2$, we show that the Julia set and the anti-Julia set coincide in the complex plane, although the pre-Julia and pre-anti-Julia sets remain completely disjoint. At the integrable limit $a\to 0$, these two dual structures undergo a critical collision and subsequent annihilation, reminiscent of a cosmological Big Crunch. When $1/2<a<1$, on the other hand, the boundary of the pre-anti-Julia set includes the Julia set. We analytically characterize these phenomena, focusing in particular on the asymptotic behavior of the pre-anti-Julia set as it approaches the integrable limit, and provide numerical visualizations that elucidate the underlying mechanisms of this Big Crunch phenomenon.
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All authors Masatomi Iizawa, Satoru Saito, Yasuhito Narita, Yasuyuki Maeda, Hiromitsu Harada, Akira Shudo
Quantum Physics
Momentum-Space-Engineered Spatial Photonic Ising Machine for Long-Range Interactions
Haijun Zhou, Hengyang Li, Maolin Wang et al. (+4 more)
Long-range Ising models (LRIMs) with dense nonlocal and competing interactions are central to statistical physics,
quantum simulation, and complex networks. Although the spatial photonic Ising machine (SPIM) exploits intrinsic optical parallelism for Ising computation, its ability to faithfully encode dense long-range couplings and capture the resulting thermodynamic signatures remains underexplored. Here, we present a momentum-space-engineered SPIM framework that maps prescribed long-range coupling kernels onto momentum-space masks for parallel
Hamiltonian evaluation. Based on a high-fidelity optical field propagation model, the annealing dynamics of LRIMs with power-law and Ruderman-Kittel-Kasuya-Yosida (RKKY) interactions are systematically investigated. For the power-law model, we investigate the modulation of the estimated critical temperature by the decay exponent {\sigma} and coupling cutoff radius R. For the RKKY model, we reproduce diverse ordered states induced by complex competing long-range interactions. A proof-of-principle experiment demonstrates the physical feasibility of our approach. This framework broadens the class of many-body systems accessible to the SPIM platform.
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All authors Haijun Zhou, Hengyang Li, Maolin Wang, Yunru Chen, Yingxiong Qin, Xiahui Tang, Gang Xu
Materials Science
Metallic-Phase-Fe$_3$GaTe$_2$ Enabled Interface Engineering for Self-Powered and High-Gain WS$_2$ Photodetectors
Wajid Ali, Ming Huang, Juan Li et al. (+7 more)
Two-dimensional transition-metal dichalcogenides offer strong light-matter interaction but suffer from inefficient carrier separation and contact-related losses in photodetectors. Here, we demonstrate a high-gain WS$_2$/Fe$_3$GaTe$_2$ van der Waals
heterostructure photodetector, where metallic Fe$_3$GaTe$_2$ serves as an active interfacial contact. The work-function mismatch, together with interfacial charge redistribution and asymmetric contact geometry, contributes to a built-in field that supports self-powered photodetection at zero bias. Under 450 nm illumination, the device delivers a zero-bias responsivity of 23.5 A/W and an apparent external
quantum efficiency of 6.4 x 10$^3$%. At -1 V biasing, the
heterostructure exhibits photoresponse at 450, 520 and 633 nm, achieving a responsivity of 9.7 x 10$^3$ A/W and a noise derived specific detectivity of 2.3 x 10$^13$ Jones at 100 Hz under 450 nm illumination. The high photoresponse is attributed to interfacial carrier separation, efficient extraction, and a likely contribution from trap-assisted photogating in multilayer WS$_2$. These results establish Fe$_3$GaTe$_2$-enabled interface engineering as an effective route for self-powered, highly sensitive 2D photodetectors.
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All authors Wajid Ali, Ming Huang, Juan Li, Jianhua Huang, Liuli Yang, Sajid Ur Rehman, Chinmay K. Mohanty, Zahir Muhammad, Ziwei Li, Maciej R. Molas
Computational Physics · Cross-listed from cs.LG
Constitutive State-Space Modeling of Path-Dependent Plasticity: A Resolution-Consistent and Parallelizable Computational Framework
Rui Barreira, Taylan Soydan, Francesco Scipione et al. (+2 more)
Data-driven constitutive models for path-dependent plasticity are commonly formulated using nonlinear recurrent neural networks, whose sequential state
evolution limits parallel training and whose predictions may depend on the discretization of the applied strain path. We introduce a Constitutive State Space (CSS) model that reformulates structured state-space dynamics as an incremental constitutive operator. The strain increment is decomposed into magnitude and direction: the loading direction drives the latent state-space system, while the increment magnitude enters the zero-order-hold discretization of its continuous-time linear recurrence. This mechanics-tailored construction guarantees stationarity under zero increments, strongly reduces sensitivity to strain-path resolution, and retains the parallel-scan structure of S5 for efficient training on long constitutive histories. The CSS and Minimal State
Cell (MSC) architectures are compared for four multiaxial path-dependent material models including isotropic J2 plasticity, pressure-sensitive foam plasticity, and combined isotropic-kinematic hardening. CSS matches or exceeds the prediction accuracy of the MSC, including one order of magnitude lower validation losses for the plastically incompressible materials. Importantly, CSS maintains low errors across large changes in strain-path discretization, whereas the MSC error increases substantially when evaluated at coarser resolutions than used for training. CSS trains substantially faster and requires fewer strain-stress pairs to attain comparable or better accuracy. Analysis of the learned state further reveals latent structure consistent with the dimensionality of the underlying physical constitutive models. These results establish mechanics-tailored structured state-space dynamics as a computational framework for efficient and discretization-robust data-driven constitutive modeling.
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All authors Rui Barreira, Taylan Soydan, Francesco Scipione, Miguel A. Bessa, Dirk Mohr
Applied Physics
An integrated viscoelastic modeling framework combining analytical and FEM approaches: Application to WSe2 coatings
Mohamed Bensalem, Fateh Bahadur, Yue Wang et al. (+2 more)
This work presents an integrated methodology combining analytical and finite element FEM based viscoelastic modeling for characterizing the nanoindentation response of coatings. The proposed framework combines two complementary modeling approaches: an analytical model based on the Burgers formulation to analyze nanoindentation load displacement data and extract rheological parameters, and a numerical FEM model implemented in ABAQUS using a 2D axisymmetric indenter coating substrate configuration with viscoelasticity represented through Prony series. An automated inverse optimization routine employing the Nelder Mead simplex
algorithm minimizes the discrepancy between experimental and simulated responses. The methodology is demonstrated and validated on WSe2 coatings, showing an agreement between the analytical predictions, FEM simulations, and experimental measurements. Despite the
geometric simplifications, the FEM approach provides accurate predictions while maintaining high computational efficiency of time dependent mechanical behavior. The proposed framework provides a robust tool for characterizing viscoelastic behavior from nanoindentation data while enabling access to internal stress and strain fields, thereby offering deeper insight into plastic deformation, crack initiation, and failure mechanism.
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All authors Mohamed Bensalem, Fateh Bahadur, Yue Wang, Nabil Daghbouj, Tomas Polcar
Solar and Stellar Astrophysics
Statistical structure and physical interpretation of the fillout factor distribution in contact binary stars
A. Poro, K. Li, E. Paki et al. (+2 more)
Contact binary systems exhibit complex evolutionary behavior governed by mass transfer, angular momentum loss (AML), and Roche geometry. The fillout factor ($f$) is widely used as a descriptor of the degree of overcontact, yet its physical and statistical role remains nonuniformly defined across the literature. We used a compiled observational sample of W UMa-type contact binaries to construct a data-driven classification framework based on $f$ and its relation to fundamental system parameters. Unsupervised clustering applied to the one-dimensional $f$ distribution reveals a robust three-class structure corresponding to shallow-, medium-, and deep-contact configurations. The statistically determined boundaries are located at $f \simeq 0.257$ and $f \simeq 0.561$, with a stable silhouette score of $S \simeq 0.613$. The stability of this classification is confirmed through perturbation tests in $f$ and parameter-conditioned samples. A random forest regression model shows that 60.7% of the variance in $f$ can be explained by the considered physical and
geometric system parameters, with
geometric parameters providing the largest predictive contribution. Among the considered parameters, the mass ratio emerges as the dominant predictor. The identified subclasses therefore appear to reflect a continuous
geometric sequence rather than discrete physical states, governed by the progressive
evolution of the Roche equipotential configuration under mass transfer and AML. Notably, the second boundary separating medium- and deep-contact systems shows lower stability than the first boundary, suggesting that the transition toward deep contact may be more sensitive to the physical composition of the analyzed sample.
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All authors A. Poro, K. Li, E. Paki, F. Alicavus, N. Alan
Quantum Physics
Implementing QESEM's High-Accuracy Error Mitigation on a Quantum Computer: a Water Potential Energy Surface Study
Renato Olarte Hernandez, Emanuele Rossi, Sonia Coriani et al. (+5 more)
Quantum error mitigation (QEM) is essential for extracting chemically accurate results from near-term
quantum hardware. Many widely used QEM methods rely on uncontrolled heuristics whose bias depends on the specific
circuit and noise realization. In this work, we employ QESEM—a characterization-based, unbiased quasi-probabilistic mitigation method—on IBM's Aachen
quantum processor to compute the ground-state potential energy surface (PES) of the symmetrically-stretched water molecule. We consider a classically-optimized, single-layer perfect-pairing tiled
unitary product state ansatz. We map this ansatz to an 8-
qubit register corresponding to a (4,4) active space and the STO-3G basis set. Compared to the statevector reference, we find that raw QPU results typically overestimate the ground-state energy by around 500~mHa across the scanned geometries. On the other hand, QESEM-mitigated results fall approximately within 100~mHa, 30~mHa, or “chemical accuracy” ($\sim$1.5~mHa), depending on the target precision. We
benchmark QESEM at both loose (0.1~Ha) and tight (0.01~Ha) precision targets, evaluating both individual and merged batches of runs. As the precision target is tightened, the accuracy improves systematically, matching or exceeding results reported in the literature. We further quantify the sampling cost of these results, reporting the number of shots required at each precision level. Our results show how, with the current levels of hardware error, reaching the highest accuracies demands substantial QPU time. The results demonstrate that the characterization-based, unbiased error mitigation provided by QESEM allows to measure quantitatively meaningful potential energy surfaces on current
quantum hardware. Concurrently, they highlight the sampling overhead associated with QEM, which remains a central bottleneck en route to larger chemical problems and higher precision.
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All authors Renato Olarte Hernandez, Emanuele Rossi, Sonia Coriani, Karl Michael Ziems, Erik Kjellgren, Jacob Kongsted, Tali Shnaider, Stephan P. A. Sauer
Earth and Planetary Astrophysics
The effect of the atmospheric C/O ratio on interiors of hot Jupiters
Esther van Dijk, Yamila Miguel and Paul Mollière
The atmosphere is the outer boundary of a gas
giant exoplanet's interior. Therefore, compositional changes in the atmosphere can affect interior inferences. Typically, only
metallicity is considered in atmospheric boundary conditions, while other elemental ratios, in particular the C/O ratio, are assumed to be
solar. In light of the observational constraints now achievable with JWST, this assumption might no longer be justified. In this work, we investigate the effect of the C/O ratio on atmospheric boundary conditions, interiors and radii of hot Jupiters. We construct an atmospheric boundary grid, consisting of one-dimensional atmospheric models in radiative-convective and thermochemical
equilibrium. This grid is coupled to a static interior structure model at the radiative-convective boundary (RCB). Because in the temperature regime of hot Jupiters, the C/O ratio determines the dominant species in the atmosphere, it can significantly alter the opacity and, consequently, the pressure and temperature at the RCB. This temperature change propagates into the convective interior, thus affecting the calculated radius. The radius difference relative to a
solar C/O-atmosphere significantly exceeds observed radius uncertainties of 3 per cent for
planets with
equilibrium temperatures $\gtrsim$ 1500 K and super-
solar atmospheric
metallicities. As an example, we demonstrate that, for WASP-19~b, higher C/O ratios result in higher inferred intrinsic temperatures. These results highlight the importance of treating atmospheric composition and interior structure as a coupled system. As atmospheric constraints improve, incorporating measured C/O ratios into atmospheric boundary conditions is necessary to obtain robust inferences of hot Jupiter interiors.
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Mathematical Physics
Renormalization group bounds on Araki relative entropy
Edoardo D'Angelo
This paper derives a multiscale Bakry-Émery criterion for an upper bound on the Araki relative
entropy of perturbations of an
equilibrium state in relativistic QFT. Using
stochastic positivity, affiliated perturbations of the relativistic bosonic field can be put in correspondence with perturbations of the massive Euclidean free field. This gives a Feynman-Kac formula, which in turns is used to derive a probabilistic expression for the Araki relative
entropy. The description of the massive Euclidean free field as an abstract Wiener space provides the infinite-dimensional framework to derive a Polchinski equation. Extending the methods of Bauerschmidt, Bodineau, and Dagallier to this context yields a probabilistic bound on the Araki relative
entropy, which can be formulated entirely in operator-algebraic terms. Using the criterion, it is shown that the Lorentzian massive Sine-Gordon model in the ultraviolet finite regime satisfies the relative
entropy bound.
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Chemical Physics
Mixed quantum-classical evolution in open molecular systems
Michael Galperin and Abraham Nitzan
We consider a mixed
quantum-classical formulation for open nonequilibrium molecular systems. We employ the pseudoparticle nonequilibrium Green's function (PP-NEGF) method as a fully
quantum description and a starting point for introducing classical
nuclear dynamics for an open system. We use this formulation to derive a density-
matrix equation of motion describing the
quantum-classical
evolution. We compare our results with previous formulations and highlight important differences related to the nonequilibrium and open character of the molecular system. We also analyze the approximations needed to reduce full
quantum-classical dynamics to the fewest-switches surface hopping (FSSH) method and show that these approximations are unreasonable when adiabatic surfaces come close to each other.
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Atomic Physics
Magnetic characterization of electronic components for portable atomic sensors using a zero-field optically pumped magnetometry platform
Hyeonjae Kim, Sangkyung Lee, Sin Hyuk Yim et al. (+2 more)
We present a zero-field optically pumped magnetometry platform for
magnetic characterization of a photodetector (PD) board and a resistance temperature detector (RTD) used in a portable atomic magnetometer. For each component, the static
magnetic field along the measurement axis is determined from the shift in the center of the dispersive response, while response distortion caused by off-axis
magnetic-field components is assessed from the absorptive admixture.
Magnetic-field noise is evaluated based on the quadrature difference in the amplitude spectral density (ASD). The platform achieved a -3 dB bandwidth of 71.5 Hz and a median ASD of 57.6 $\mathrm{fT}/\sqrt{\mathrm{Hz}}$ over 20-70 Hz. For the unpowered PD board, static
magnetic fields of approximately 8 nT in magnitude and opposite signs were measured in the front- and back-facing orientations. The back-facing orientation also exhibited a degraded dispersive response consistent with
magnetic-field inhomogeneity. The
magnetic-noise contributions associated with the PD board were estimated at 36.0 and 63.2 $\mathrm{fT}/\sqrt{\mathrm{Hz}}$ in the front- and back-facing orientations, respectively. By contrast, operation of the RTD readout generated a static
magnetic field of -0.6 nT, with no measurable response degradation or additional
magnetic-field noise. These results provide guidance for the design and placement of electronic components in portable atomic magnetometers targeting sensitivities below 0.1 $\mathrm{pT}/\sqrt{\mathrm{Hz}}$.
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All authors Hyeonjae Kim, Sangkyung Lee, Sin Hyuk Yim, Taek Jeong, Younghoon Lim
Quantum Physics
Spectral Criterion for Disorder-Free Localization of Quantum Walks on Hypercube: QBN Approach
Ce Wang
We study disorder-free localization in a
spin-coupled
quantum walk on the hypercube within the
quantum Bernoulli noises framework. We derive a general criterion for disorder-free localization: it occurs if and only if some spectral subspace of a reduced
unitary evolution contains a vector whose position marginal probability is non-uniform. For the Grover walk with distance-dependent coupling \(\phi_\sigma=|\sigma|\pi/(n+1)\) in dimension \(d=4\), we explicitly construct a non-uniform fixed point in the all \(+1\)
spin configuration. This implies that disorder-free localization occurs in our model.
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General Relativity and Quantum Cosmology
Thin accretion-disc transfer functions in the q-metric spacetime: quadrupolar lensing signatures
Saken Toktarbay, Manas Khassanov, Aray Muratkhan et al. (+3 more)
We study geometrically thin equatorial disc images in the static, axisymmetric q-metric spacetime using backward ray tracing. The Schwarzschild solution is recovered at $q=0$; for the nonzero deformations considered here, $r=2M$ is a
curvature singularity rather than an event horizon. For a distant nearly face-on observer, we construct the first three equatorial transfer functions $r_m(b;q)$. In the {Schwarzschild} limit, the resolved third-crossing interval contains the critical impact parameter $b=3\sqrt{3}M$. As $q$ increases from $-0.3$ to $0.3$, the branch center shifts from $b_{3,c}/M\simeq3.716$ to $6.702$. In units of the physical monopole mass $\mathcal M=(1+q)M$, it instead decreases from $b_{3,c}/\mathcal M\simeq5.309$ to $5.156$. Much of the displacement in metric-parameter units therefore reflects the changing monopole scale. At fixed $\mathcal M$, the inclined first-intersection maps show that the contour dimensions increase with $q$, with larger relative changes near the inner disc. A prescribed power-law emissivity and relativistic frequency-shift weighting yield direct images whose integrated flux differs from the Schwarzschild value by at most $2.4\%$. Between the endpoint models, the horizontal median-flux position increases by $8.8\%$ and the interquartile width by $14.5\%$. Within this emission prescription, the residual deformation dependence appears mainly as a displacement and broadening of the brightness distribution. Higher-order radiative contributions are not included.
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All authors Saken Toktarbay, Manas Khassanov, Aray Muratkhan, Zhantay Muratkhan, Aliya Taukenova, Hernando Quevedo
Quantum Physics
Qubit-Based Benchmarking of InP HEMT LNAs: Readout Fidelity Versus Power Consumption
Junjie Li
High-fidelity single-shot readout of superconducting
qubits is essential for fault-tolerant
quantum computation. Without a
quantum-limited amplifier such as a Josephson parametric amplifier, the cryogenic high-electron-mobility-transistor (HEMT) low-noise amplifier (LNA) at the 4 K stage is the dominant noise source in the readout chain. HEMT LNAs are conventionally characterized by Y-factor measurements of the noise temperature $T_N$, independently of the
quantum measurement they ultimately serve. Here we present a
qubit-in-the-loop benchmarking method. The method uses the two-dimensional IQ histogram of single-shot readout as a direct figure of merit. We apply it to three state-of-the-art cryogenic InP HEMT LNAs with 53%, 60%, and 70% channel indium content, together with a commercial reference amplifier. The 60% and 70% devices have similar $T_N$ in Y-factor measurements, both lower than the 53% device. The 70% device has the highest gain, but
qubit readout SNR and assignment fidelity $\mathcal{F}_a$ instead peak at 60%. Using this method, we map $\mathcal{F}_a$ against HEMT LNA dc power consumption for each device. $\mathcal{F}_a$ does not simply saturate with increasing power. For several devices it declines above a device-dependent power well below typical operating points. For the 60% device, which has the highest overall $\mathcal{F}_a$, about 1~mW is needed to maintain $\mathcal{F}_a > 85\%$. Across all four devices, $\mathcal{F}_a > 80\%$ is reached with as little as about 0.3~mW, roughly an order of magnitude below typical operating points. These results establish a
qubit-referenced benchmarking methodology and provide practical guidance for amplifier selection and bias in power-constrained multi-
qubit readout systems.
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Fluid Dynamics
Weakly nonlinear dynamics of a follower-force active filament in simple shear flow
Ory Schnitzer
We employ weakly nonlinear theory to investigate how an externally imposed simple shear flow affects the onset of spontaneous dynamics of an inertialess active filament deforming in Stokes flow. The filament, clamped to a wall at one end, is subjected to a compressive "follower force" applied tangentially at its free end. By extending my earlier weakly nonlinear analysis of the shear-free case (J. Fluid Mech., 1007 A65, 2025), we derive a generalized amplitude equation governing the near-onset dynamics under weak shear. Analysis of the amplitude equation shows that, besides inducing a steady deflection, the shear damps the filament's intrinsic oscillations. This damping arises from a subtle nonlinear resonance between the shear and the intrinsic oscillations, scales quadratically with the shear rate, and is anisotropic—stronger in the flow direction than normal to it. Without shear, stable whirling states, where the filament tip traces a circular orbit in a plane parallel to the wall, and unstable planar-beating states are known to simultaneously emerge at a critical follower-force value, with circular whirling typically observed beyond this threshold. Shear breaks this degeneracy, driving a sequence of dynamical transitions: from circular to elliptical whirling, then to transverse beating (normal to the shear), and ultimately to steady deflection.
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