Peer Revenue Equity in science

Papers

Fresh from arXiv, typeset properly. Highlighted words trade on the market.

Physics

Watch Physics (sign in to use)

Monday 21 September

Mathematical Physics · Cross-listed from math.OA

A complete characterization of eventually entanglement breaking unital quantum channels

We obtain a complete characterization of eventually entanglement breaking (EEB) unital channels in terms of some simple commutation properties of their eigenvectors. Specifically, the following properties are equivalent for a unital channel: (i) it is EEB; (ii) it is eventually positive partial transpose (PPT); (iii) it is eventually mixed twisted dephasing; and (iv) its eigenvectors corresponding to non-zero eigenvalues commute with all its peripheral eigenvectors. Similar results hold for one-parameter semigroups of unital quantum channels, where continuity forces such semigroups to become primitive. We employ a matrix integral technique inspired by a result of Watrous. We also characterize the extreme points of the convex set of unital EB channels and, using this characterization and the theory of equiangular tight frames (ETFs), identify several extreme points beyond the twisted dephasing channels.
Read the full abstract

Quantum Physics

Nondemolition filtering of an embedded cluster-state scar under continuous local monitoring

Identifying a low-entanglement eigenstate inside a many-body spectrum and preserving it during measurement are distinct tasks. We construct an explicit local ring Hamiltonian with an exact cluster-state eigenvector and study continuous monitoring of its stabilizer defects. For arbitrary mixed inputs, the conditional cluster fidelity is the initial target weight divided by the no-observed-click probability. A positive defect-operator gap gives finite-time bounds that hold for noncommuting Hamiltonian dynamics, nonnormal effective generators and imperfect detection. At fixed total monitoring rate, the guaranteed exponent falls inversely with system size; high conditional fidelity does not remove the preparation cost set by the initial overlap. Exact diagonalization up to eleven qubits gives finite-size evidence for a cluster-state outlier in a chaotic spectral background. Independent matrix and trajectory calculations verify the dynamics and a conservative coherent-error bound. This construction specializes established scar embedding and nondemolition verification frameworks, with explicit measurement assumptions, finite-time guarantees and resource limitations.
Read the full abstract

All authors Ximo Wang, Xi Zhao, Xiayu Sun, Qiwei Han, Yuhang Wang, Chunxiao Du, Wenxiu Li, Hao Zhang, Rui Li

Fluid Dynamics

Mechanism-Separated Closed-Form Transition Modeling via Field Inversion and Symbolic Regression

Next-generation aircraft, rotorcraft, and wind turbines demand improved aerodynamic efficiency, making drag reduction a central design objective; in transition-sensitive configurations, the extent of laminar flow strongly affects viscous drag and performance. Accurate prediction of laminar-turbulent transition is therefore essential. Transport-equation-based transition models, however, increase computational cost and implementation complexity. Neural-network-based closures can be difficult to interpret and integrate into independent flow solvers, while a single compact correction trained on heterogeneous transition data may fail to preserve mechanism-specific behavior. This study develops a mechanism-separated transition model using field inversion and symbolic regression. The framework treats natural, crossflow, and separation-induced transition with separate correction branches and yields explicit, closed-form corrections to the Spalart-Allmaras production term, without additional transport equations or runtime neural-network inference. The closed-form model is implemented in an independent flow solver to assess implementation portability and is evaluated on canonical cases and complex three-dimensional configurations, including a natural-laminar-flow transport wing and a hovering rotor. Across the tested cases, the model captures the principal transition-front trends and associated aerodynamic-performance changes. For the hovering-rotor case, it requires about 55% of the wall-clock time of the comparable transport-equation transition model.
Read the full abstract

Statistical Mechanics

Derivation of the Thiele equation for magnetic skyrmions using the Mori-Zwanzig formalism

We use the Mori-Zwanzig formalism to derive an exact generalized Langevin equation governing the dynamics of magnetic skyrmions. Using standard approximations, this generalized Langevin equation is found to reduce to the usual Thiele equation. Our approach provides a general route for obtaining extensions of the Thiele equation applicable to magnetic textures and degrees of freedom not covered by the standard derivation route. It also provides some insights into the microscopic justification of the standard Thiele equation, specifically concerning contributions of fast modes to the form of the drift and diffusion terms in the Fokker-Planck equation for skyrmions.
Read the full abstract

General Relativity and Quantum Cosmology

Soliton solution of a gravitating chiral quark soliton model: dynamical fermion and Dirac-sea in general relativity

In this paper, we study Einstein-Dirac system based on a Dirac fermion coupled with a nonlinear chiral field on static spherically symmetric spacetime. Gravitational effects on the dynamical mass of fermions are examined. The chiral quark soliton model (CQSM) originally was a model of hadron inspired by the low-energy regime of large-$N_\textrm{c}$ QCD, realizing localized fermions with the full inclusion of the Dirac-sea, which is derived from a regularized one-fermion loop. We extend the CQSM in spherically symmetric curved spacetime and coupled with the Einstein gravity. We successfully solve the CQSM and the Einstein equation self-consistently, and obtain the spectral flow of the fermion energies and also of the ADM mass. The Dirac-sea dilutes the effect of the energy-momentum tensor, which induces an inactive point for the impact of gravity even when the localizing matter exists. The Dirac-sea effect becomes dominant for larger dynamical mass $M\sim \langle\bar{\psi}\psi\rangle$, leading to the emergence of the negative ADM mass.
Read the full abstract

Mathematical Physics · Cross-listed from math.PR

The Fixed-$q$ Edge Limit of the $q$-Krawtchouk Ensemble

We study the fixed-$q$ right-edge asymptotics of the ordinary $q$-Krawtchouk ensemble. For $0<q<1$, finite polynomial duality gives a direct proof of convergence of the correlation kernels to an explicit limiting kernel. The local Jacobi limit is a shifted continuous $q^{-1}$-Hermite expression with an indeterminate moment problem, so the limiting Jacobi expression does not determine a unique self-adjoint operator. A single spectral atom, asymptotically saturating the mass bound, selects the realization and yields strong-resolvent convergence. The limiting kernel represents its positive spectral projection and admits spectral-series, Christoffel–Darboux, and partial-theta representations. After a ground-state transformation, the associated dual operator agrees with a two-step spatial Markov operator of Borodin–Corwin. For $q>1$, the limiting Jacobi operator is of Al-Salam–Carlitz~I type and is essentially self-adjoint.
Read the full abstract

Quantum Physics

Reconstructing the phonon distribution of trapped ions out of the Lamb-Dicke regime

Characterizing the phonon distribution of trapped-ion motional states is essential for many applications in quantum information processing, but existing methods become ill-conditioned beyond the Lamb-Dicke regime. We overcome this limitation by recasting phonon-state reconstruction as a filter-function inversion problem. Using composite pulses on the carrier and multiple sidebands, we engineer well-conditioned filters in phonon space to characterize pure and mixed states, study heating dynamics, and reconstruct Fock states up to $n=250$.
Read the full abstract

All authors Christophe H. Valahu, Prachi Nagpal, Teerawat Chalermpusitarak, Maverick J. Millican, Cameron McGarry, Frank Scuccimarra, Vassili G. Matsos, Hon-Kwan Chan, Ting Rei Tan

Quantum Physics

Sparse and weak-measurement certification of graph-edge entanglement in PXP scar wavepackets

An imperfect many-body revival does not by itself certify the entanglement of the returning state. We give a finite-record protocol for graph-edge localizable entanglement along scar wavepackets of a graph-dressed PXP chain. The target cluster state has nonzero energy variance, so neither an exact target eigenstate nor a dark-state embedding is assumed. Fresh binary probes of the undeformed Hamiltonians Pauli terms have a fully separable explanation, even within the dressed blockade sector. Adding local graph-stabilizer probes makes established entanglement witnesses accessible with simultaneous confidence bounds. For a specified square-root instrument, an imposed worst-case disturbance budget fixes the strength that minimizes the equal-allocation Hoeffding sufficient sampling cost. A local commutator bound accounts for finite-duration ancilla pulses while the Hamiltonian remains active. We test the protocol on chains through twenty spins, under perturbed dynamics, and with independent implementations. At the first twenty-spin return, synthetic weak records certify all nineteen graph edges. Generator, two-color, bounded-weight, and full-group benchmarks separate this localizable resource from genuine multipartite certification. The protocol measures recoverable entanglement in a known scar wavepacket, with explicit calibration and limits on its physical and statistical interpretation.
Read the full abstract

All authors Ximo Wang, Yichi Zhang, Qiwei Han, Xi Zhao, Yuhang Wang, Chunxiao Du, Rui Li, Wenxiu Li, Hao Zhang

Quantum Physics

Pauli-resolved virtual distillation

Learning the full Pauli profile of the virtually distilled quantum state $\rho^m/\text{tr}(\rho^m)$ has so far required exponentially many copies of $\rho$. We show that all $4^n$ squared Pauli moments $[\text{tr}(P\rho^m)]^2$ can be learned to additive error $\varepsilon$ with confidence $1-\delta$ from one $2m$-replica measurement setting using $O(m[n+\log(1/\delta)]/\varepsilon^2)$ copies. This is an exponential speedup in the system size $n$ over previous protocols. For $m = 2$, we propose the coherent Bell difference sampling circuit that realizes this measurement on current devices. The speedup originates from paired replicas that cancel the anticommutation signs of Pauli operators, collapsing the incompatibility of the Pauli family. We certify this collapse by introducing the quantum Bernstein norm, a computable incompatibility measure for nonlinear functionals. A further information-theoretic $m$-replica protocol recovers the signed moments $\text{tr}(P\rho^m)$ using $O(m[n+\log(1/\delta)]/\varepsilon^4)$ copies. For fixed $m$ in the stated lower-bound regime, it attains the optimal replica number, since any protocol with fewer replicas requires exponentially many copies.
Read the full abstract

All authors Si-Yuan Chen, Congcong Zheng, Kun Wang, Ming-Cheng Chen

Optics

Hypervectors from Optical Disorder: Programmable Encoding and Optical Inference for Hyperdimensional Computing

Hyperdimensional computing (HDC) is a computing framework that represents information as high-dimensional pseudorandom vectors called hypervectors (HVs), enabling learning and inference through simple algebraic operations. The HV dimensionality provides computational capacity and error robustness, but the required high-dimensional randomness must be stored or regenerated, imposing a memory–computation tradeoff. Here, we address this tradeoff by physically embodying the randomness required for HV generation in the static disorder of a scattering medium. Specifically, a silicon photonic circuit combined with the scattering medium generates high-dimensional HVs from a small number of input values in a single optical shot. Detector-side encoding programs HV correlations for continuous and categorical representations. The resulting HVs reproduce key statistical and compositional properties of ideal i.i.d.\ random HVs, including pairwise similarity statistics, associative-memory capacity, and factorization capacity. We further demonstrate an optically assisted inference path using the generated HVs and optical similarity evaluation.
Read the full abstract

Materials Science

Polar vibrational excitations and glass-like response in relaxor PMN

Relaxor ferroelectrics retain crystalline order while exhibiting glass-like dielectric and thermal responses. Using atomistic models trained on first-principles data, we investigate these responses in the prototypical relaxor Pb(Mg_{1/3}Nb_{2/3})O_3 (PMN). Compositional disorder couples elastic motion to electric polarization, producing a continuum of polar vibrational excitations, unlike the discrete polar optical modes of conventional ferroelectric PbTiO_3. The simulations qualitatively reproduce the temperature dependence of the low-frequency susceptibility, while the calculated far-infrared spectra agree closely with experiments. At low frequencies, disorder in PMN generates a boson peak comprising excess phonon-like modes and quasi-localized excitations. The latter exhibit a quartic frequency dependence of their density of states and pronounced anharmonicity, as in structural glasses. These excess modes account for PMN's anomalous behavior in the specific heat for temperature higher than 5 K. These results connect the dielectric, optical, and thermal anomalies of a crystalline relaxor through its disorder-induced polar excitation spectrum.
Read the full abstract

All authors Kehan Cai, Pinchen Xie, Yifan Li, Roberto Car

High Energy Astrophysical Phenomena

Constraints on Axion-like Dark Matter from Cosmic Birefringence with a Polarization Array of Repeating Fast Radio Bursts

Axion-like dark matter (ALDM) is a well-motivated dark matter candidate whose Chern-Simons coupling to photons can induce cosmic birefringence, producing temporal oscillations and spatial correlation in polarization angle (PA) signals from different sources. Hyperactive repeating fast radio bursts (FRBs) with high linear polarization are a particularly promising probe of such signatures. We develop a Bayesian framework to search for PA oscillations caused by ALDM in individual repeating FRBs, and combine multiple sources in an FRB polarization array (FRBPA) by exploiting correlations arising from the common Earth term. We apply this framework to PA datasets from three well-studied hyperactive repeating FRBs, and constrain the Chern-Simons coupling over a broad range of ALDM masses. For each FRB, we estimate the dark matter density at its host location using a simulation-calibrated halo profile. The inferred dark matter densities are comparable to the fiducial local density $\rho_0 = 0.4~\mathrm{GeV/cm^3}$. The comparable source and Earth dark matter densities, together with the redshift-induced difference between the frequencies of the source and Earth terms, motivate our adoption of the full two-component birefringence model. We find no compelling evidence for ALDM-induced PA oscillations in either the individual source analyses or the joint FRBPA analysis. We place 95% credible upper limits on the Chern-Simons coupling strength as a function of ALDM mass. Across the axion mass from $10^{-23}$ to $10^{-18}~\mathrm{eV}$, the resulting upper limits of the coupling strength of FRBPA lie between $10^{-12.6}$ and $10^{-7.9}~\mathrm{GeV}^{-1}$. Our results establish long-term polarimetric monitoring of hyperactive repeating FRBs as a promising and independent probe of ALDM, with sensitivity expected to improve with longer observational baselines and larger source samples.
Read the full abstract

All authors Xiaohui Liu, Zi-Yan Yuwen, Yun-Long Zhang, Zerui Liu, Shiqian Zhao, Shuai Feng, Wei-Yang Wang, Xuelei Chen

Materials Science

Enhanced thermal conductivity of (010) (AlxGa1-x)2O3 epitaxial films utilizing indium-catalyzed molecular beam epitaxy

(AlxGa1-x)2O3/beta-Ga2O3 transistors are an emerging candidate for high-power and high-frequency electronic devices. beta-Ga2O3 in particular is notably limited for anisotropic low thermal conductivity, which is further reduced in (AlxGa1-x)2O3 due to alloy and other defect-driven phonon scattering mechanisms. In this work we show that the thermal conductivity of (010) oriented (AlxGa1-x)2O3 thin films for 0.01 < x < 0.20, measured using time-domain thermoreflectance (TDTR), is limited by alloy scattering without observable adverse scattering by additional defects. This is enabled through the synthesis of the (AlxGa1-x)2O3 films using molecular beam epitaxy (MBE) on e̱ta}-Ga2O3 substrates, leveraging indium-catalyzed growth to suppress dislocation formation and phase separation to achieve single-phase pseudomorphic films up to x = 0.2. This growth process improved the thermal conductivity of (AlxGa1-x)2O3 by 2X as compared to previously reported values. For increasing Al composition (x), we observe a steady decline in (AlxGa1-x)2O3 thermal conductivity due to alloy scattering which is validated using virtual crystal approximation (VCA) model. We also show that the thermal boundary conductance across the Al/(AlxGa1-x)2O3 interface is reduced with increasing x, which we posit is due to the stiffening of the (AlxGa1-x)2O3 acoustic modes with increasing x by comparing experimental results with a diffuse mismatch model (DMM). Overall, these thermal characteristics provide valuable insights for designing heterostructures with optimized interfaces and composition.
Read the full abstract

All authors Shivashree Gowda, Stephen Schaefer, Ethan A. Scott, Samreen Khan, Patrick E. Hopkins, M. Brooks Tellekamp

Nuclear Theory

Time-evolution formalism in the complex scaling method: Application to the two-proton decay of $^{6}$Be

We apply our complex-scaled time-evolution operator to the two-proton decay of $^{6}$Be. The nucleus is described as an $\alpha+p+p$ three-body system with explicit Jacobi-coordinate rearrangement and the realistic Argonne $v8'$ NN interaction for the proton-proton subsystem. Starting from a confined initial wave packet, the decay dynamics are described by expansion over the complex-scaled eigenstates of the final Hamiltonian. The decay width extracted from the late-time survival probability agrees closely with that obtained from the CSM resonance pole. The time-dependent densities in different Jacobi coordinates reveal complementary aspects of the evolving three-body geometry, while the spin-singlet component remains dominant during the decay. In particular, the correlated two-proton configuration persists even in the presence of the strong short-range repulsion of the realistic NN interaction. These results demonstrate the applicability of the complex-scaled time-evolution framework to explicit three-body decay dynamics and provide a consistent description of the decay width, spatial evolution, and spin correlations of $^{6}$Be.
Read the full abstract

Quantum Physics

Trace-distance-based complementarity relations in a multipath interferometer

The complementarity relations in an interferometer reflect an important phenomenon in quantum mechanics: wave-particle duality. Here, we develop a method to quantify both wave and particle behaviors in a multi-path interferometer. In particular, we find that the trace distance is a good candidate for wave and particle measures. As a result, some duality relations and triality ralations are established respectively. This work not only extends the application of the trace distance to the interferometer, but also opens up new perspectives on the quantification of waveness and particleness.
Read the full abstract

All authors Yue Sun, Jingyan Liu, Peng-Tong Li, Chenxu Li, Ming-Jing Zhao

Applied Physics · Cross-listed from eess.AS

Performance Analysis and Design of an Optomechanical Microphone Using an Integrated Photonic Waveguide Interferometer

We present an optomechanical microphone based on a diaphragm-integrated photonic waveguide Mach-Zehnder interferometer. Acoustic pressure deforms the MEMS diaphragm, inducing strain in the sensing waveguide and changing its optical path length. We analytically evaluate the optical and mechanical transduction mechanisms and key figures of merit, including signal-to-noise ratio, dynamic range, acoustic overload pressure, and minimum detectable pressure. Two design cases are considered: a MEMS microphone and a measurement microphone. The results indicate competitive performance but no substantial overall advantage over state-of-the-art microphones in conventional applications. The architecture may nevertheless offer advantages for high-temperature and other harsh-environment sensing applications.
Read the full abstract

All authors Xiaoyu Niu, Yuqi Meng, Zihuan Liu, Ehsan Vatankhah, Neal Hall

Fluid Dynamics · Cross-listed from math.NA

Accurate wall shear stress in immersed flow analysis with application to point cloud-based CFD

Point cloud-based CFD enables flow analysis directly on discrete points obtained from 3D scanning and medical imaging, bypassing surface reconstruction, geometry cleanup, and boundary-fitted mesh generation. Derived from immersogeometric analysis, the method immerses the point cloud in a background mesh and enforces no-slip conditions on discrete points through a Nitsche-based weak boundary condition (BC). The framework delivers accurate velocity fields, pressure distribution, and integrated loads; however, accurate prediction of the local wall shear stress (WSS) has remained a critical challenge. The geometry intersects the background mesh arbitrarily, producing cut elements that lack the regularity required for consistent gradient evaluation. The issue is compounded by the stabilization term of the weak BC, whose parameter estimation in the symmetric Nitsche formulation is dependent on the cut configuration and affects the variationally consistent definition of traction from which the WSS is computed. In this work, we propose a new method to obtain accurate wall shear stress in immersed flow analysis with application to point cloud-based CFD, using a non-symmetric Nitsche's formulation with near-wall modeling and a patch-based stress recovery approach with traction compatibility. The method is validated on canonical benchmarks and applied to turbulent flow past a sphere and to a patient-specific aorta, showcasing excellent agreement with reference results.
Read the full abstract

Physics Education

Johann Bernoulli's analysis of elastic collisions (a teaching sequence to introduce the dynamic law thereby inspired)

In order to explain an elastic collision, Johann Bernoulli considered two bodies connected by a spring. Motion is defined as a succession of states of rest. Then, considering the spring to be a lever with a body at each extremity, the laws of equilibrium imply that `motion' is described by the time variation of the (common) quantity of motion of the bodies; the dynamic law is thus deduced. This inspires a teaching sequence to introduce the dynamic law (in one dimension) in introductory physics course; we call it “bernoullian sequence”.
Read the full abstract

Statistical Mechanics

Exact Nonperturbative Equilibrium Mode Statistics in Nonlinear Wave and Lattice Systems

We derive exact finite-size nonperturbative representations of equilibrium modal occupations and related statistics for three representative nonlinear systems: the Majda-McLaughlin-Tabak dispersive-wave model, the Fermi-Pasta-Ulam-Tsingou beta anharmonic chain, and the discrete nonlinear Schrodinger lattice field. Independent simulations confirm the predictions from weak to strong nonlinearity. For DNLS, the theory remains accurate across the weak-coupling quasicondensation crossover, where large low-mode occupations and long-range coherence amplify interaction effects even when the bare nonlinear coefficient is small. The finite-ring DNLS occupations are further resolved into a positive sum of Rayleigh-Jeans channels with distinct correlation lengths, explaining when a single Rayleigh-Jeans law applies and why it fails near quasicondensation. In MMT and DNLS, the exact occupations also determine the mean modal frequencies even when the dynamical spectra broaden or split. The nonperturbative results allow a direct assessment of two representative perturbative approaches. Treating the mean interaction appropriately yields accurate low-order approximations, including at strong nonlinearity. At higher orders, however, the corrections cease to decrease and successive approximations oscillate with increasing amplitude; both finite-order approaches also fail near weak-coupling quasicondensation. Thus neither low-order agreement nor a small bare coupling guarantees a reliable perturbative description. The results establish nonperturbative equilibrium theory for widely used nonlinear wave and lattice models and provide a quantitative basis for modal distributions of energy, particles, and optical power in nonlinear optics, dispersive waves, anharmonic lattices, and cold-atom systems.
Read the full abstract

Astrophysics of Galaxies

A Sample of 459 Galaxy Groups Identified from the FAST All Sky HI Survey DR2

Groups of HI-rich galaxies are key laboratories for understanding galaxy evolution and environmental effects, constructing samples of such groups is fundamental for relevant studies. Using the FAST All Sky HI Survey (FASHI) Data Release 2 (DR2), currently the largest and deepest HI catalog available, we identify galaxy groups directly from HI signals, without relying on optical pre-selection. A group-finding algorithm with a density contrast criterion and a minimum membership of five yields a catalog of 459 galaxy groups containing 3015 HI sources. Using archival spectroscopic data, we identify optical counterparts and derive total stellar masses of member galaxies as a proxy for the group total mass. The group redshift distribution peaks at z ~ 0.02, and the total HI mass peaks at ~ 10^{10} M_{\odot}. We find a significant positive correlation between total HI mass and total stellar mass, consistent with the increase in HI mass with halo mass reported in previous stacking studies. The ratio of total HI mass to total stellar mass decreases significantly with increasing total stellar mass, indicating gradual HI depletion in groups. Our sample provides rich targets for future studies of galaxy evolution and large-scale structure in the local Universe.
Read the full abstract

Mathematical Physics · Cross-listed from math.PR

A Linear Variance Bound for Ballistic Deposition

We show the height at time $t$ of the standard continuous-time ballistic deposition process has variance at most $C_d t, t \geq 1$ in every dimension $d \geq 1$. The crucial idea is to adapt a martingale argument due to Aldous, which gives tail bounds on first hitting times for monotone surface growth processes. Inverting these tail bounds and applying a duality theorem due to Penrose yields a linear variance bound for the height of ballistic deposition.
Read the full abstract

Optics

Adaptive Solitons

Femtosecond laser pulses have incredible potential but still face some performance and stability issues. Here we discover a new nonlinear optical effect, frequency-comb-induced stimulated Brillouin scattering resonance, which can only be excited by a new type of soliton, adaptive solitons. Adaptive solitons possess the unique properties of adaptive down-chirp which breaks area theorem limitation on pulse energy in normal dispersion lasers, spectral profile self-regulation which provides high pulse contrast and breaks gain narrowing limitation in amplifiers, and freedom from dispersive radiation that weakens and deforms current ultrashort laser pulses in transmission media. More intriguingly, they have an adaptive transmission gain in normal dispersion waveguides which has the potential to enable them to be lossless in long normal dispersion waveguides for repeaterless soliton communication. A passive frequency-modulation mode-locked fiber laser was successfully built and generated incredibly stable adaptive solitons. Even though the laser had no negative dispersion elements, the output solitons were measured as down-chirped which enables them to keep soliton properties in normal dispersion waveguides, perfect for ultrafast applications with waveguide delivery. With the advantages of high consistency, high pulse contrast, and high energy capability; adaptive solitons are excellent for fields including micromachining, laser surgery, quantum computing, and spectroscopy.
Read the full abstract

All authors Yuchuan Chen, Jiacheng Zhao, Qiuran Zhu, Bill Chen

Strongly Correlated Electrons

Carrier duality from the convergence of Dirac fermions and high-order van Hove singularities

The convergence of highly mobile Dirac fermions and flat-band heavy electrons offers a paradigm for emergent quantum phenomena. However, experimental realization of such intriguing state remains elusive. In this study, we report a dual carrier regime in the kagome metal Co3In2S2, wherein the charge transport is governed by high-mobility electrons while the thermodynamic responses exhibit heavy-electron behavior. This exotic duality arises from the coexistence of topological Dirac fermions and flat-band high-order (4th-order) Van Hove singularities (HOVHSs) at the Fermi surface, as revealed by magnetic-torque quantum oscillation and angle-resolved photoemission spectroscopy. The interaction between Dirac and HOVHS-derived carriers can be captured by a minimal two-pocket model, manifesting as sublinear resistivity above ~100 K and field-induced non-Fermi-liquid behavior at low temperatures. Our study establishes Co3In2S2 as a model platform for exploring many-body physics at the intersection of topology and correlation effects, and provides a foundational framework for designing quantum materials hosting diverse emergent states.
Read the full abstract

All authors Meng Lyu, Kaiyi Zhai, Nikolai Peshcherenko, Junyan Liu, Jinying Yang, Subir Sen, Binbin Wang, Langsheng Ling, Zhaosheng Wang, Gang Li, Jieyi Liu, Yang Xu, Xiyang Li, Claudia Felser, Yang Zhang, Wujun Shi, Lexian Yang, Enke Liu

Optics

Synthetic-Aperture Super-Resolution Imaging via Spatial-Frequency Shift in Near-Field Diffraction

Grating-based computational imaging shifts high-spatial-frequency information into the detectable range, enabling super-resolution reconstruction. However, a fixed grating produces effective diffraction-mediated shifts only for specific spatial-frequency vectors, limiting spatial-frequency coverage. Here, we propose a synthetic-aperture super-resolution method in which repeated imaging with a rotating grating broadens spatial-frequency coverage and expands the effective aperture. A physics-prior-guided restoration framework then employs a multichannel deep-learning network to fuse images acquired at different grating orientations. Using diffraction images from only three grating orientations, the proposed method reconstructed the object with a resolution of $\lambda/3.9$. This approach offers a practical route to grating-modulated super-resolution imaging in systems with limited numerical aperture.
Read the full abstract

All authors Qihao Sun, Chunzheng Bai, Wenjing Fang, Zongyan Zhang, Songlin Yang, Yonghong Ye, Mingyi Tao, Jiayu Zhang

Chemical Physics

From Heuristics to Machine Learning: The Performance Ceiling for Single-Ion Magnets and Its Electronic Origin

Machine learning (ML) is expected to speed up the discovery of single-ion magnets (SIMs), but does the structural information available before synthesis allow such predictions? For 1215 lanthanide complexes from the SIMDAVIS 1.2.1 database we compared three increasing levels of structural description: tabular features of the coordination site, continuous symmetry measures of the coordination polyhedron, and the complete 3D arrangement of atoms. All three converge to an accuracy near 76%, only slightly above the 71% of the single rule "predict SIM for Dy3+". To explain the failures, we combined multireference ab initio calculations with an inspection of the structures behind the high-confidence errors. The SIMs missed by the geometric models are field-induced relaxers whose ground Kramers doublets are prone to tunnelling, a property invisible to geometric descriptors. Many false positives contain several lanthanide centers or radicals, so their relaxation is collective and outside the single-ion picture. The electronic-structure and connectivity information needed to identify SIMs is therefore not accessible to geometric methods alone. Geometric models remain useful: restricting the screening to compounds with high prediction confidence raises the accuracy to 88% while retaining 48% of the dataset. Building on the analysis of the failures, we propose a strategy that combines simple filters for nuclearity and for radicals with ligand-field descriptors from ab initio calculations.
Read the full abstract

All authors Federico Zahariev, Regina Pereyra, Vassiliki-Alexandra Glezakou, Durga Paudyal

High Energy Physics (Theory) · Cross-listed from math.CT

An Equivalence of Categories between 3-Crossed Modules and Gray 4-Groups

In this paper, we investigate the relation between the category of 3-crossed modules and the category of Gray-type 4-groups. The notion of a 3-crossed module was first introduced by Arvasi et al., motivated by the question of what kind of algebraic structure completely encodes a homotopy 4-type. On the other hand, from the point of view that higher groups are equivalent to algebraic realizations of higher categories – as exemplified by the relationship between 2-crossed modules and Gray 3-groups established by Sarikaya–Ulualan – it had not been clear how the 3-crossed modules of Arvasi et al. relate to any higher category. In our previous paper, we proposed a new definition of a 3-crossed module and observed that it admits a natural interpretation in terms of higher categories. In this paper, we make this interpretation precise: we introduce a 4-category, which reduces to a semistrict braided monoidal 2-category when restricted to a single object and a single 1-morphism, and prove that the category of our 3-crossed modules is equivalent to the category of Gray 4-groups, defined as single-object versions of this 4-category in which all morphisms are invertible. Furthermore, while Gray 4-groups provide a conceptual framework for 4-dimensional higher structures, they are often computationally intractable. Our equivalence establishes 3-crossed modules as a concrete, group-theoretic calculus for Gray 4-groups, providing a powerful computational tool for studying surface knots, state-sum invariants, and higher gauge theories.
Read the full abstract

Optics

Sustained Orbital Motion Driven by Circularly Polarized Light in Nanoscale Stator-Rotor Architectures

Light-induced forces and torques offer a versatile strategy for remotely actuating microscopic objects, enabling breakthroughs including optical trapping and light-driven nanomachines. Extending such optical actuation to sustained cyclic motion, however, requires fundamentally distinct designs and, in particular, forces capable of delivering nonzero mechanical work over repeated cycles. Here, we demonstrate via simulations a nanoscale stator-rotor architecture, which achieves persistent orbital motion of a spherical rotor under circularly polarized plane-wave illumination. An off-center rotor displacement defines a stator-rotor structural polarity. Optical helicity coupled to this polarity generates a tangential force perpendicular to the instantaneous stator-rotor direction; as the rotor moves around the stator, the force direction rotates with it. Electrodynamic symmetry analysis identifies this response as arising from antisymmetric, nonconservative forces that produce nonzero closed-cycle work, whereas linear polarization yields symmetric, conservative responses with zero closed-cycle work. Material screening and Bayesian optimization identify an Ag-nanoshell design region, while Pareto analysis balances tangential actuation and radial confinement. A balanced candidate is predicted to lower the maximum steady-state temperature rise from 56.2 to 20.9 K relative to Au at the same light intensity. Brownian-dynamics simulations further show confined, helicity-defined orbital motion, with all 32 trajectories retaining the same circulation direction. These results establish a symmetry-guided route toward sustained cyclic optical actuation at the nanoscale.
Read the full abstract

All authors Shiye Du, Juanshu Wu, Xin Chen, Mouhong Lin, Hongyu Chen

High Energy Physics (Phenomenology)

Three-Body Holonomy as a Toy-Model Mechanism for Family Triplication and Mass Hierarchy in (1+1) Dimensions

We investigate the phenomenological consequences of a genuine three-body holonomy in a relativistic Dirac system in one spatial dimension. After removing the center-of-mass coordinate, the triple-coincidence point punctures the two-dimensional relative configuration space and permits a nontrivial $U(1)$ winding phase, whereas the pairwise Sakamoto–Munakata–Ino contact interactions give trivial net matching around this point. At fixed intrinsic parity, the six particle-ordering sectors reduce to a three-dimensional cyclic space. A Hermitian $C_3$-invariant effective mass operator admits a Peierls-type realization in which the gauge-invariant phase around the three links equals the three-body holonomy $\theta_3$. Its eigenvalues are $$ M^{[k]}=M_0+2\Delta\cos\!\left(\frac{\theta_3+2\pi k}{3}\right), \qquad k=0,1,2. $$ The holonomy lifts the conjugate-channel degeneracy and can generate a parametrically light branch through cancellation between the common mass and the holonomy-induced shift. We further allow cyclic-symmetry breaking and consider a general Hermitian three-state mass matrix. Exact elimination of two heavy states by the Schur complement yields a low-energy correction containing the rephasing-invariant loop product $\mathrm{Re}(t_{12}t_{23}t_{31})\propto\cos\theta_3$. Thus, even when only one branch is kinematically accessible, its effective mass can retain finite memory of the complete three-state loop. The complementary invariant $\mathrm{Im}(t_{12}t_{23}t_{31})\propto\sin\theta_3$ is phase sensitive but does not alone imply CP violation. The construction provides a low-dimensional phenomenological proof of concept for family-like triplication, mass hierarchy, and infrared memory, rather than a microscopic theory of Standard Model fermion generations.
Read the full abstract

Optics

Square-Root Higher-Order Exceptional Points with Symmetry-Induced Multiple Spectral Responses

We generalize square-root procedure to non-Hermitian systems with finite lattices, providing a spectral operation scheme applicable to arbitrary tight-binding models. Via this generalized square-root approach, we construct novel chiral-symmetric higher-order exceptional points (EPs) with multiple spectral responses. By taking square-root of a parent Hamiltonian hosting an $n$th-order EP (EP$_n$), an EP$_{2n+1}$ chiral-symmetric square-root system is obtained, whose lattice sites are inherited from both the parent system and an auxiliary residual system. The chiral-symmetry-induced structure of the generalized eigenspace enables onsite and coupling perturbations to selectively generate spectral responses of different orders. The proposed scheme is universal, applicable to any existing tight-binding EP system and iterable to generate EPs of arbitrarily high order. With enriched ultrasensitive spectral responses, the chiral-symmetric higher-order EP system provides a promising platform for signal amplification, detection and non-Hermitian control.
Read the full abstract

All authors Haoyang Zhang, Yadi Niu, Nuo Wang, Zihan Mo, Ying Gu

Mesoscale and Nanoscale Physics

Scalable Multiple Electron Transport Architectures for Feedback Traceable Current Sources

We present a scalable electron-counting current cell based on a floating gate architecture operated as a Multiple Electron Transport device (MET). The system enables controlled injection, transport, and precise quantification of discrete charge packets using the sensor non-destructive multiple readout capability. We repurposed the charge-injection technique, jointly with the electron-resolution capability, for a controlled generation of quantized charge packets for an electron-traceable current source. Scalable architectures based on parallel and series multi-amplifier configurations are explored. Experimental results confirm noise reduction following the square root of the number of independent measurements and demonstrate stable, programmable output current. This approach provides a compact and scalable platform for electron-counting current sources and precision quantum metrology applications.
Read the full abstract

All authors Agustin Javier Lapi, Guillermo Fernandez Moroni, Fernando Chierchie, Fabricio Alcalde Bessia, Miqueas Ezequiel Gamero, Brenda Aurea Cervantes Vergara, Blas Junior Irigoyen Gimenez, Eduardo Paolini, Claudio Rodrigo Chavez Blanco, Juan Estrada, Javier Tiffenberg