Cosmology and Nongalactic Astrophysics
Combining Systematic Effects in CMB Polarization Experiments through map-based simulations: application to LiteBIRD's HWP non-idealities and detectors non-linearity
Silvia Micheli, Francesco Piacentini, Tommaso Ghigna et al. (+10 more)
We quantify the impact of coupled instrumental systematics on next-generation CMB polarization experiments targeting
primordial $B$-mode polarization, with a focus on the forthcoming LiteBIRD satellite mission. We study the interplay between the non-linear response of Transition-Edge Sensor (TES) bolometers and Half-Wave Plate (HWP) non-idealities, in particular synchronous signals arising from differential emissivity. We develop a map-based formalism that captures the resulting intensity-to-polarization leakage by explicitly solving the binning map-making equations, avoiding the need for computationally expensive time-ordered data simulations. We apply this framework to LiteBIRD, adopting its baseline scanning strategy and frequency configuration, and perform analyses at both single- and multi-frequency levels, including
Galactic foregrounds and blind component separation. We find that while detector non-linearity and HWP non-idealities individually induce negligible bias on the tensor-to-scalar ratio $r$, their coupling can generate non-trivial contamination, driven by large signals such as the
solar dipole and amplified in high-frequency channels by foreground leakage. From these results, we derive joint requirements on detector non-linearity and HWP differential emission, and discuss their implications for the instrument design and calibration strategy of LiteBIRD and future CMB polarization missions targeting $r \lesssim 10^{-3}$.
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All authors Silvia Micheli, Francesco Piacentini, Tommaso Ghigna, Alessandro Carones, Alessandro Novelli, Giampaolo Pisano, Giulia Barbieri Ripamonti, Alessandro Coppolecchia, Paolo de Bernardis, Silvia Masi, Andrea Occhiuzzi, Alessandro Paiella, Simone Stellati
Nuclear Theory
Neural-Network-Based Variational Method in Nuclear Density Functional Theory: Application to the Kohn–Sham method
Kenta Yoshimura and Kazuyuki Sekizawa
We extend the neural-network-based variational method for
nuclear density functional theory to the Kohn–Sham scheme, representing the complex spinor components of the single-particle orbitals by multi-layer perceptrons. We show that neural-network optimization of a given energy density functional, combined with an orthonormalization post-processing step, is mathematically equivalent to the variational condition projected onto the tangent space of the wave-function
manifold spanned by the network parameters, and that the training optimizes not only the expansion coefficients but also the basis functions themselves. We assess the method from three points of view. In the first place, we examine how the results depend on the number of units, the number of layers, and the arithmetic precision, and find that quantitative accuracy requires both a sufficient width and a sufficient depth, while single-precision arithmetic is sufficient to represent the
nuclear density distribution. In the second place, the binding energies and charge radii of several closed-shell
nuclei agree with conventional Skyrme–Hartree–Fock results, and the quadrupole deformations of open-shell
nuclei are consistent with reference calculations that include pairing and with experiment. In the third place, we confirm that a neural-network single-particle basis can represent the three-dimensional configurations of the fundamental pasta phases: spheres, rods, and slabs. The framework offers a new perspective on computational
nuclear theory, well suited to the forthcoming generation of GPU- and AI-oriented high-throughput supercomputers.
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Materials Science
Metastable defects in III-Nitrides
A.E.Belyaev
Metastable states in III-nitrides (AlN, GaN, InN and their
alloys) are an important topic across materials science, device physics, and epitaxial growth because these compounds exhibit multiple competing
crystal structures, defect configurations, and phase behaviors that strongly affect optical, electrical, and mechanical properties. The paper is a concise, structured review-style summary covering the main concepts, mechanisms, experimental signatures, theoretical approaches, and device implications. Actions that should be proposed to avoid effect of metastable defects in III-Nitride based devices are discussed. Avoiding metastable defect effects in III nitride devices requires preventing their formation (through growth and doping control), stabilizing their electronic configuration (by annealing or optical activation), and designing device architectures that minimize field- or temperature induced transitions. These combined actions ensure consistent carrier density, higher mobility, and superior optical and electrical reliability in GaN , AlGaN , and InGaN based devices.
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Geophysics
A Frequency-Aware Dynamic Knowledge Distillation Framework: An Effective Tool for Bridging Low- and High-Frequency Seismic Information
Jun Ma, Xinyang Wang and Xintong Dong
Seismic data contain rich information across different frequency bands, with low-frequency components primarily characterizing large-scale geological structures and high-frequency components preserving fine-scale seismic details. Effectively integrating these frequency-dependent components is essential for seismic feature learning to better preserve structural continuity and fine-scale details. Knowledge
distillation provides an effective means for transferring informative representations from high-quality data. However, existing
distillation-based frameworks usually treat seismic features in a full-band manner, ignoring relationships across frequency bands and thereby limiting the coordinated transfer of low- and high-frequency knowledge. To bridge low- and high-frequency seismic features through knowledge
distillation, we propose a frequency-aware dynamic knowledge
distillation framework (FADKD-Net), which establishes a teacher-student learning framework and performs frequency-aware knowledge transfer between low- and high-frequency bands. Specifically, FADKD-Net decomposes seismic features into low- and high-frequency components and performs targeted
distillation to exploit their complementary information. Low-frequency
distillation guides the student model to learn stable structural priors, thereby improving the overall continuity of seismic events. Meanwhile, high-frequency
distillation enhances detailed feature modeling and improves the representational capability for complex and small-scale structures. Furthermore, a cross-domain feature
alignment strategy is proposed to reduce distributional discrepancies across different surveys and enhance the transferability of the seismic representations learned by FADKD-Net.
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Quantum Physics
Quantum-Based Optimization of Gas Throughput in Natural Gas Transmission Networks Under Hydraulic Constraints Using QAOA
Alex Ben Ishay, Yuval Eyal, Yuval Cohen et al. (+1 more)
Maximizing gas throughput in transmission networks under hydraulic and operational constraints is a combinatorial problem whose complexity grows exponentially with network size, making it computationally intensive to solve exactly. This paper addresses the graph-based optimization problem by optimizing nodal-pressure assignments under the Panhandle-B hydraulic equation. By framing the problem as a search over discretized nodal-pressure assignments coupled with a cost
Hamiltonian that encodes both the delivery objective and physical-constraint penalties, we establish a unified formulation suitable for the
Quantum Approximate Optimization
Algorithm (QAOA). The mathematical model is adapted to a Quadratic Unconstrained Binary Optimization (QUBO) formulation and implemented using the Classiq
quantum software platform. In simulator-based experiments, QAOA recovered the maximum-throughput valid operating point, consistent with classical exhaustive evaluation and classical hydraulic simulation reference solutions. A distinctive contribution of this work is the end-to-end execution of a reduced problem instance on the IonQ Forte-1 trapped-ion
quantum processor. Remarkably, the hardware implementation used only $p=2$ QAOA layers, substantially fewer than the $p=30$ layers used in the simulator-based study. Despite this significant reduction in
circuit depth, the QPU produced physically valid and interpretable candidate solutions that bracketed the continuous classical optimum, with each located within one pressure-discretization step of it. These results demonstrate that meaningful gas-network optimization behavior can be obtained using considerably shallower QAOA
circuits than initially expected and provide an end-to-end proof of concept for near-term
quantum-assisted gas-network optimization.
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All authors Alex Ben Ishay, Yuval Eyal, Yuval Cohen, Nati Erez
Biological Physics · Cross-listed from q-bio.NC
Temporally constraining source imaging estimates in an underdetermined neural system with eigenmodes of cortical geometry
Pok Him Siu, Philippa J. Karoly, Artemio Soto-Breceda et al. (+2 more)
Geometric eigenmodes provide a compact and biologically grounded representation of large-scale neural activity. Previous work demonstrated that they can mitigate the underdetermined nature of electroencephalographic (
EEG) and magnetoencephalographic (MEG) source localisation, an ill-posed inverse problem in which neural activity is reconstructed from non-invasive recordings. Beyond their spatial structure, neural field theory predicts the temporal
evolution of eigenmodes through analytically derived transfer functions. Motivated by this framework, the present work investigates whether these transfer functions can be used to introduce temporal constraints into
EEG source imaging. The approach is evaluated using simulated seizure dynamics generated by coupled Epileptor neural mass models. Transfer functions derived directly from neural field theory were found to be generally ineffective as temporal constraints for source localisation, primarily because they neglect cross-eigenmode coupling. Incorporating empirically estimated coupling terms substantially improves localisation performance, particularly in noisy conditions. Although estimating these eigenmode coupling interactions from experimental data remains challenging, the findings motivate dynamical source imaging approaches that combine spatial eigenmode structure with empirically informed cross-modal dynamics.
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All authors Pok Him Siu, Philippa J. Karoly, Artemio Soto-Breceda, Mark J. Cook, David B. Grayden
Cosmology and Nongalactic Astrophysics
Baryonic feedback suppression of the matter power spectrum: a three-parameter fitting formula and its single-parameter reduction
Pengjie Zhang
Baryonic feedback can suppress matter clustering by $\sim 10\%$ at $k\sim 1h$/Mpc and $z\sim 1$, and is therefore a major source of systematic errors in weak
lensing cosmology. We investigate this effect through the ratio $S(k,z)\equiv P_{\rm hydro}(k,z)/P_{\rm DMO}(k,z)$ measured in the FLAMINGO, IllustrisTNG, and Illustris hydrodynamical simulation suites, together with the one-parameter-at-a-time (1P) variation runs of CAMELS-TNG and CAMELS-SIMBA. We present a three-parameter fitting formula that reproduces all but one of these runs with maximum error less than $0.03$ (and typical error less than $0.01$) at $k\leq 3h/$Mpc and $z\leq 2$; the only exception is a run with unrealistically low $\Omega_m=0.1$. Each of the three parameters ($B_0$, $n$, and $a$) has a clear physical interpretation: $B_0$ sets the characteristic scale of the suppression at $z=0$, corresponding to a gas particle displacement scale of $B_0^{1/2}$; $n$ sets the suppression floor $(1-\Omega_b/\Omega_m)^n$; and $a$ sets the
redshift $z_B$ at which the suppression peaks. Furthermore, we find that $B_0$ and $z_B$ are significantly correlated for most runs. Also, $n\simeq 1$ for FLAMINGO, TNG and CAMELS-TNG. For these simulations, the description reduces to a single parameter formula with maximum error less than $0.03$. The formulas remain accurate at max$(|\Delta S|)<0.03$ (and typical error less than $0.01$) for cosmologies well away from the calibration cosmology, spanning the range $\Omega_m\in [0.2,0.5]$, $\Omega_b\in [0.029,0.069]$ and $\sigma_8\in [0.6,1.0]$. These results imply that, despite the diversity of baryonic physics implementations, an accurate description of $S(k,z)$ requires at most three effective degrees of freedom. Therefore the impact of feedback on weak
lensing cosmology can in principle be mitigated internally without significant loss of cosmological constraining power.
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Solar and Stellar Astrophysics
The Influence of Evaporation on the Formation and Evolution of Huntsman Systems
Hao-Ran Yang, Shi-Jie Gao, Xiang-Dong Li et al. (+2 more)
Huntsman systems are a recently identified and rare subclass of millisecond
pulsar (MSP) binaries, characterized by a detached
neutron star and an evolved
giant companion in relatively wide orbits. Their formation has been proposed to involve red-bump-induced detachment, whereas the influence of MSP-driven evaporation during this evolutionary stage has not yet been quantitatively assessed. We quantify the influence of MSP-driven evaporation on the formation and
evolution of Huntsman systems and assess its effects on their observable properties. We performed detailed binary
evolution calculations including MSP-driven evaporation over a wide range of initial binary parameters and combined them with binary population synthesis to predict the observable population of Huntsman systems. We find that Huntsman systems originate primarily from binaries undergoing Case B mass transfer and red-bump-induced detachment, with initial donor masses of $1.0-2.5\ M_\odot$ and orbital periods above the bifurcation period. Evaporation has a secondary effect, slightly modifying the orbital
evolution and the duration of the detached phase, but does not significantly alter the formation parameter space or the expected population, which contains about 10 Huntsman systems. We further show that evaporation can produce systematic shifts in the white
dwarf mass-orbital period relation at the low-mass end, leading to systematically wider final orbits for a given white
dwarf mass.
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All authors Hao-Ran Yang, Shi-Jie Gao, Xiang-Dong Li, Yun-Lang Guo, Wen-Shi Tang
Materials Science
Shangfei Wu, Laur Peedu, Zhihao Wang et al. (+12 more)
Point defects have been successfully utilized in various
quantum technologies, serving as
quantum qubits for
quantum computation, single-
photon emitters for
quantum communication, and nanoscale sensors for
quantum metrology. However, their further development faces key challenges, particularly in discovering and exploring suitable defect-host systems that meet the necessary criteria for
quantum applications. Here, using polarization-resolved Raman spectroscopy and terahertz absorption spectroscopy, we discover three distinct chromium-vacancy-induced excitations in the uniaxial
antiferromagnetic insulator, Cr$_2$O$_3$. These vacancy-induced excitations have an energy scale of a few tens of millielectronvolts and are twofold degenerate, and the lowest one at 64 $cm^{-1}$ is sharp and sensitive to the external
magnetic field along the easy-axis direction, particularly close to the
spin-flop regime around 6T, where the mode softens from 64 to 27$cm^{-1}$. Based on the defect supercell first-principles calculations, we interpret the mode at 64 $cm^{-1}$ as a local
magnetic excitation of the local moment within the chromium vacancy state. Our results establish that the
magnetic defect states in Cr$_2$O$_3$ have potential for
quantum applications.
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All authors Shangfei Wu, Laur Peedu, Zhihao Wang, Xuecong Wang, Xianghan Xu, Kai Du, Sang-Wook Cheong, Aleksei Boldin, Joosep Link, Ivo Heinmaa, Raivo Stern, Sai Mu, Urmas Nagel, Toomas Rõõm, Girsh Blumberg
High Energy Physics (Theory)
Carroll Limit of $\mathcal{O}(F^2)$ $\text{D}_p$-branes from Kaluza–Klein-like Null reduction in the Polyakov Formulation
Limin Zeng
We construct the electric and
magnetic Carroll limits of the $\mathcal{O}(F^2)$-truncated $\text{D}_p$-brane via the Polyakov–KK route, which combines a single-mode Kaluza–Klein-like reduction at fixed light-cone momentum with a Dirac classification that keeps the auxiliary worldvolume frame. Unlike the $U(1)$-free ILST string, for $p\geq2$ the Carrollian D$_{p}$-brane cannot be treated as a consistent fixed-frame constrained system after the Dirac classification. In the electric family the obstruction is directly produced by the worldvolume $U(1)$ matter sector, while in the
magnetic family the frame retention is forced by the scalar kinetic's density-weight structure rather than by the $U(1)$ currents. The frame must therefore be retained through the classification and eliminated afterwards by Dirac brackets. Freezing it beforehand is not a legitimate step in the Dirac procedure. The
embedding scalar sector inherits the Carroll–Weyl $\chi$ structure at the level of the ILST kinetic density, which is $\chi$-invariant, whereas the full scalar action is only $\chi$-covariant. The local extension of $\chi$ to the full matter sector is obstructed by the $U(1)$ sector through the Gauss, circle and $A_-$-gradient brackets. The electric family keeps the global rescaling as a weak
symmetry, while the
magnetic family fails even for a global parameter. For $P_{-}\neq0$ the electric and
magnetic families have $d-2$ and $d-3$ degrees of freedom, and the restored local circle at $P_{-}=0$ removes one further degree of freedom in each family. These features identify the resulting theories as constrained systems distinct from both the null string and the parent $\mathcal{O}(F^2)$ DBI theory, and we also discuss their on-shell interpretation and relation to tensionless/null strings.
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Materials Science
Agentic programs: an emerging form of scientific software in computational materials science
Yunsung Lim, Haekwan Jeon, Jaesun Kim et al. (+2 more)
Computational materials science has traditionally delegated algorithmic tasks to computers while leaving scientific judgments to humans. We argue that recent LLM-based
agent harnesses enable an emerging form of scientific software, agentic programs, that combine deterministic
algorithms with bounded LLM-based judgment, task-specific verification, episodic maturation, and complete delegation in production. We illustrate this concept with DeMARS, an agentic program for constructing atomistic models from experimentally measured disordered
crystal structures.
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All authors Yunsung Lim, Haekwan Jeon, Jaesun Kim, Jisu Kim, Seungwu Han
Mathematical Physics
Blow-Up, Asymptotics, and Improbability of Collision Singularities in the n-Body Problem
Nathan Duignan and Manuel Quaschner
We study finite-time singularities in $n$-body systems with pair potentials that are homogeneous of degree $-\alpha$, where $0<\alpha<2$, that are not necessarily attractive and with bounded time-dependent external forces. We develop a systematic method to analyse a colliding subsystem in the presence of simultaneous collision or non-collision singularities elsewhere in the system. We extend classical results of von Zeipel and Painlevé to such subsystems, establish bounds on their internal energy near total collision, and implement a McGehee blow-up that remains effective without conservation of energy. The blow-up yields the asymptotics of the cluster size, and in the case of attractive potentials, the convergence towards the set of central configurations and asymptotics of relative position, relative velocities, and internal angular momentum. As an application of the asymptotic results, we construct a simplified proof that the initial conditions leading to collision form a set of measure zero.
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Mesoscale and Nanoscale Physics
Anti-higher-order Weyl semimetal
Cheng-Ming Miao, Yu-Hao Wan and Qing-Feng Sun
Higher-order
topology extends the bulk-boundary correspondence by enabling corner or hinge localized states. Here we identify an anti-higher-order Weyl semimetal, a three dimensional topological phase in which the conventional boundary hierarchy is reversed. Unlike conventional higher-order Weyl semimetals where bulk
topology enforces hinge
Fermi arcs, this phase hosts anti-hinge states, meaning the bulk
topology forces states to vanish at specific hinge orientations. Using a minimal two-band model, we show how Weyl points separate the Brillouin zone into
quantum anomalous
Hall and anti-higher-order topological insulating regions, with the latter characterized by a band-inversion surface enclosing two distinct high-
symmetry points carrying opposite topological charges. Analytical solutions for Weyl points, Berry
curvature monopoles, and slice Chern numbers are derived, with numerical simulations confirming the resulting anti-hinge behavior. Our work establishes anti-higher-order
topology as a dual counterpart to conventional higher-order phenomena, further extending the exploration of topological phases.
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Mesoscale and Nanoscale Physics
Anti-higher-order topological insulators
Cheng-Ming Miao, Yu-Hao Wan, Ying-Tao Zhang et al. (+1 more)
Duality is a fundamental concept in physics that connects complementary opposites like particles and holes. Similarly, while topological states in topological
insulators localize at boundaries, the existence and nature of their dual counterparts remain unexplored. Here, we introduce anti-topological states as the dual of topological states, exemplified by anti-higher-order topological
insulators. Unlike higher-order topological
insulators, where states localize at corners, anti-higher-order topological
insulators host states along edges but absent at corners, realizing an inverted distribution of states. We demonstrate this phenomenon in a
bilayer Chern
insulator with opposite Chern numbers, where the band inversion surfaces enclose distinct high-
symmetry points. The topological invariant distinguishing these phases is given by the topological charges enclosed by band inversion surfaces. This work establishes anti-
topology as a new paradigm, opening a chapter in topological research.
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All authors Cheng-Ming Miao, Yu-Hao Wan, Ying-Tao Zhang, Qing-Feng Sun
Quantum Physics
High-Rank Encoding Can Improve Approximate Quantum Error Correction
Bikun Li and Liang Jiang
Conventional
quantum-code constructions encode pure logical states as pure code states, but this restriction can sacrifice performance. We show that intrinsic encoding randomness can improve optimal
entanglement fidelity. We bound the loss from imposing a rank-one encoder and prove it is at most quadratic near perfect recovery after joint optimization. The optimized advantage survives small noise perturbations. An explicit noise family requires higher-rank encoders arbitrarily close to perfect recovery, with every optimal encoder mapping pure inputs to mixed code states.
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Quantum Physics
Superconducting Flux Memory for Cryogenic Applications
Gregory R. Boyd, Jeremy Clark, Mark Covington et al. (+15 more)
We report the development of flux
memory for use with superconducting
circuits. This technology stores persistent currents in superconducting loops on-chip to be used to provide flux biasing for superconducting
circuits, like
qubits. We developed three types of flux
memory and draw comparisons among them for
circuit design. We demonstrate the utility of flux
memory by using an in-situ flux detector and characterize each approach and further demonstrate that once flux is set in a
memory cell, benchtop DC control sources can be powered off, leaving the on-chip flux bias in place. We propose that flux
memory can be arranged in a two-dimensional configuration to multiplex control signals and reduce how line counts scale (N^2 devices -> 2N control lines), and our experimental results pave the path to the proposed scalability. We demonstrate the use of flux
memory to flux bias a transmon
qubit and show the tunability of the
qubit state to a target frequency which remained stable on-chip for 20 hours.
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All authors Gregory R. Boyd, Jeremy Clark, Mark Covington, David G. Ferguson, Aref Fouladi, Keith D. Hillaire, Moe Khalil, John McFarland, Aaron Pesetski, Anthony J. Przybysz, John X. Przybysz, Sambarta Rakshit, Aruna N. Ramanayaka, Brian Sears, Robert Smith, Colin Stack, Robert M. Young, Tony X. Zhou
Instrumentation and Methods for Astrophysics
$\texttt{BilbyFlow}$: user-friendly neural posterior estimation for gravitational-wave astronomy
Liam Pinchbeck, Eric Thrane, Csaba Balazs et al. (+1 more)
Bayesian inference plays a central role in the new field of gravitational-wave astronomy. However, traditional
Bayesian inference with
stochastic samplers is computationally expensive, taking hours to days per event. Transformative changes are therefore required to enable the science of next-generation observatories whose event rates and signal-to-noise ratios will increase significantly over the current generation. Recent work has shown that neural posterior estimation (NPE) is a promising path forward. A neural net is trained to approximate the posterior distribution of gravitational-wave parameters, allowing generation of posterior samples in a fraction of the time required by
stochastic samplers. In this work, we introduce $\texttt{BilbyFlow}$, which harnesses the power of NPE in the popular $\texttt{Bilby}$ code suite. We use $\texttt{BilbyFlow}$ to analyze a subset of 38 high-mass events from the third LIGO-Virgo-KAGRA Gravitational-Wave Transient Catalog (GWTC-3). For 29 events (76%), we obtained an importance-sampling efficiency $>$1%, allowing us to produce reliable posterior distributions within 3 min - 1.5 hours. For the other events, with importance-sampling efficiency $\ll$1%, the run time can be as long as 35 hours. We achieve a median importance-sampling efficiency of 7%, which is roughly comparable to the $\texttt{DINGO}$ package. We aim to significantly improve this efficiency with further development to make the runtime more reliably $O(\text{min})$. $\texttt{BilbyFlow}$ is open source and $\texttt{pip}$-installable.
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All authors Liam Pinchbeck, Eric Thrane, Csaba Balazs, Paul Lasky
Mathematical Physics
Cid Reyes-Bustos and Masato Wakayama
The
quantum Rabi model occupies a distinguished role in the study of
quantum light and matter, describing the most fundamental interactions. Elucidation of its spectral properties, along with those of its generalizations, is necessary for
quantum optics and applications in areas such as
quantum information technologies. In this paper, we explore a precise description of energy degeneracy of the two-
photon asymmetric
quantum Rabi model and the nature of the system's
symmetries; as a result, we demonstrate that these have significant relationships with the structure of certain algebraic curves (hyperelliptic curves) and number theory. Concretely, we first prove the existence of degenerate
eigenvalues using the monodromy data of the Fuchsian ODE, which draws the
eigenvalue problem of the system, and the existence of associated
symmetry operators, previously discovered and studied heuristically in physics. Subsequently, we give a complete characterization of spectral degeneracies and present a series of
conjectures showing that the degeneracy may determine the entire energy spectral structure. More precisely, for sufficiently strong interaction, we obtain an excellent approximation of the energy curves by the zero locus of a two-variable
polynomial associated to degenerate eigenstates. In addition, we postulate an explicit description of the relation between the missing
symmetry at the
Hamiltonian level (hidden
symmetry) and the degeneracy of the two-
photon quantum Rabi model.
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Optics
Photonic magnetism and altermagnetism without magnetic materials
Tiancheng Zhang, Lijie Li, Zhuo Liu et al. (+7 more)
Magnetism, a fundamental property of solids arising from the collective
alignment of electronic
spins of
magnetic atoms, has recently been expanded by the discovery of altermagnetism, a
symmetry-driven phase distinct from both ferromagnetism and antiferromagnetism. Initial efforts to emulate altermagnetism in photonic systems are also being pursued, primarily through the magneto-optic response of materials; however, their intrinsic frequency limitations pose challenges for extending photonic altermagnetism into the optical regime, thereby restricting their material choices and optical applications. Here, we establish a microscopic framework of photonic magnetism through group theory
symmetry analysis, defining photonic counterparts of electron
spin and
magnetic atoms. This approach enables the realization of photonic
ferromagnetic,
antiferromagnetic, and altermagnetic phases within structured optical
lattices constructed by purely dielectric, nonmagnetic materials, which not only broadens the photonic magnetism concept, but also lifts the material and frequency limitations. Analytical models, numerical simulations, and experimental measurements reveal
spin-momentum locking directly corresponding to their electronic analogs, showing d-, g-, and i-wave circular dichroism (CD) splitting bands at telecom wavelengths (around 1550 nm). These results demonstrate that altermagnetic order, and magnetism more broadly, can be reconstructed in photonic systems through
symmetry and mode coupling alone, opening a new route towards
spin-dependent light control and bosonic analogs of
quantum magnetic phenomena in dielectric photonic
crystals.
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All authors Tiancheng Zhang, Lijie Li, Zhuo Liu, Li Lei, Yi Li, Fanhao Meng, Changhao Ding, Moses C. Hong, Scott Dhuey, Jie Yao
Fluid Dynamics
Scaling of boundary-layer disturbances exposed to free-stream turbulence
Pierre Ricco
We present theoretical results related to the experimental findings of Matsubara and Alfredsson (2001) on the scaling of the energy spectra of the Klebanoff modes, i.e. streamwise-elongated vortical disturbances generated by free-stream
turbulence in a flat-plate transitional boundary layer. The scaling is explained by a model that describes the streamwise
evolution of the streamwise and spanwise energy spectra. The theoretical framework is based on the quasi-steady asymptotic solution of the boundary-region equations, on an axial-symmetric model of the free-stream spectrum, and on the spectral response of the boundary layer to the external perturbations.
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Instrumentation and Methods for Astrophysics
Addressing the low-wind effect with the Lyot-based low-order wavefront sensor on SCExAO
Garima Singh, Sebastien Vievard, Julien Lozi et al. (+5 more)
The Low-Wind Effect (LWE) is a well-known issue that affects the coronagraphic capabilities of instruments optimized to take direct images of
exoplanets. This effect is prominent in segmented and obstructed pupils with spider arms, causing differential pistons due to phase discontinuities and, in some cases, tip-tilt errors under low-wind conditions. LWE-induced low-order errors contribute to coronagraphic leakage and reduce the
exoplanet detection sensitivity of direct imaging instruments. Solutions to mitigate the impact of LWE have been developed in both passive mode, such as coating the spider arms with low-emissivity material, and active mode using wavefront sensors (WFS). The Subaru Coronagraphic Extreme Adaptive Optics (SCExAO) instrument at the Subaru
Telescope also attempted to mitigate LWE by testing several dedicated WFS. Such techniques, when tested on SCExAO, have proven their ability to measure and correct LWE; however, most remain incompatible with SCExAO's coronagraphic imaging modes. Addressing the need for an efficient solution that can correct LWE in coronagraphic observing modes, we revisited the coronagraphic WFS on SCExAO, known as the Lyot-based Low-order Wavefront Sensor (LLOWFS). LLOWFS utilizes the unused starlight reflected off the Lyot stop and is a well-proven technique that can prevent coronagraphic leaks by sensing low-order errors in a re-imaged focal plane or pupil plane downstream of the focal plane mask. We present the machine-learned LLOWFS's initial on-sky measurement and control of the differential piston aberrations induced by the LWE downstream of a Lyot coronagraph in SCExAO's infrared arm. Preliminary LLOWFS corrections of LWE in the coronagraphic mode are encouraging and would leverage future high-contrast performance of SCExAO, enabling the detection of mature
exoplanets at small angular separations.
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All authors Garima Singh, Sebastien Vievard, Julien Lozi, Vincent Deo, Andre Fogal, Kyohoon Anh, Olivier Guyon, Sandrine Juillard
Mesoscale and Nanoscale Physics
Classifying coherent peaks in nanoelectronic devices by the presence or absence of spin exchange
Jongbae Hong
Coherent peaks appearing in the differential conductance of
quantum-dot single-electron transistors (QDSETs) and
quantum point contact (QPC) devices are classified into two categories according to the scaling function onto which the temperature-scaled differential-conductance maxima collapse and the underlying
spin dynamics. The zero-bias peaks (ZBPs) observed in QPCs and in the triplet state of the even-particle sector of QDSETs belong to the same category, whereas the ZBP in the odd-particle sector of a QDSET belongs to a different category together with all finite-bias coherent peaks observed in QPCs and in the even-particle sector of QDSETs. The
spin dynamics of the former category involve
spin exchange, a hallmark of Kondo dynamics, whereas those of the latter category involve only cotunneling of an up–down
spin pair. Furthermore, for the former type of ZBP, the scaling temperature coincides with one-half of the full width at half maximum (FWHM), which corresponds to the Kondo temperature. In contrast, for the latter type, the scaling temperature does not coincide with the (1/2)FWHM-derived energy scale. To support these findings, the gate-voltage-dependent differential-conductance line shapes measured in the odd-particle sector of a QDSET are theoretically reproduced. The results demonstrate that the observed ZBP is a merging of two coherent side peaks generated solely by the cotunneling of up–down
spin pairs.
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High Energy Physics (Theory) · Cross-listed from math.RT
Scary Wheels (and Super Shrubs)
Andrei Neguţ and Alexander Tsymbaliuk
We prove the shuffle realization for
quantum affine superalgebras of types $B,C,D$ in the loop realization, in that we construct an isomorphism between each of these
algebras and a suitably defined double shuffle
algebra. We explicitly describe the latter shuffle
algebra using certain vanishing conditions that generalize the Feigin-Odesskii wheel conditions; a novel feature is the appearance of a so-called scary wheel, which is a particular order $2$ vanishing condition involving $7$ variables. Along the way, we fully develop the theory of shrubs in super types $A$ (affine and toroidal), which are important combinatorial tools in the study of the shuffle
algebras associated to toric Calabi-Yau threefolds. Our techniques also allow us to define
quantum toroidal superalgebras of types $B,C,D$. More importantly, we provide a general framework to formulate and prove shuffle realizations in the wide generality of quivers with parameters.
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Disordered Systems and Neural Networks · Cross-listed from q-bio.QM
Efficiently classifying shocks in complex systems requires dormant reporters
David A. Brewster and Philippe Cluzel
Many natural and engineered systems are large complex networks of interacting components, and external perturbations drive them along different dynamical paths. Identifying which perturbation occurred matters for diagnosis, control, and prediction. Yet often times only a few components can be jointly monitored. Which components should be monitored? Experimental practice usually favors placing reporters at the most sensitive sites, where perturbations produce the largest effects. Using a simple dynamical model for complex systems with heterogeneous connectivity, we ask how sparse reporter panels should be chosen to classify shocks from partial trajectories when repeated trials only approximately reproduce an ideal initial condition. Once that reproduction is imperfect, sensitivity ranked panels fall far short of optimal, and the shortfall grows with the noise. We find that the best panels mix two kinds of reporters. A promiscuous reporter responds to most shocks, so it separates them mainly by degree, and degree fluctuates from trial to trial. A dormant reporter responds to only a few shocks but strongly, and its answers do not scatter as much between trials. As noise grows, the cost of losing a dormant reporter rises to meet the cost of losing a promiscuous one. Panels of either kind alone classify worse than the mixture, and no property of the members collected individually explains the ordering. Most of all, we find that only a minuscule number of reporters are needed on a panel to accurately identify which shock hit the system. We implement an efficient
algorithm to assemble such a panel. Together these results provide a low cost practical design principle for monitoring large complex dynamical systems.
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Materials Science
Phase Switchable Photocatalytic Water Splitting via a Paraelectric-Ferroelectric Transition in Zr2Ge2S6 Monolayer: A Comprehensive Theoretical Insights
Jubair Hossan Abir, Tauhidur Rahman, Md. Tanvir Khan et al. (+3 more)
Photocatalytic water splitting (PWS) is a promising technology for addressing the global energy crisis and producing renewable and clean hydrogen fuel. Although numerous 2D materials have recently been proposed as potential photocatalysts, effective strategies for regulating photocatalytic reactions and improving energy conversion efficiency remain limited due to performance regulation challenges. Here, using first-principles calculations, we demonstrate that the photocatalytic activity and energy conversion efficiency of a Zr2Ge2S6 monolayer can be effectively tuned through a paraelectric-ferroelectric phase transition. The Zr2Ge2S6 monolayer exhibits excellent structural stability, favorable mechanical properties, a suitable band gap, optimal band edge positions, and broad-spectrum light absorption. Moreover, the Zr2Ge2S6 monolayer exhibits a higher oxidation potential and a stronger driving force for photogenerated holes to promote oxygen
evolution reaction (OER) in the ferroelectric phase. In contrast, the paraelectric phase provides photogenerated electrons with a greater reduction potential and driving force for hydrogen
evolution reaction (HER). The
solar-to-hydrogen conversion efficiency is also strongly influenced by the phase transition, increasing from 7.71% in the paraelectric phase to 15.31% in the ferroelectric phase because of the improved carrier utilization. Our theoretical investigation not only highlights the crucial role of ferroelectric polarization in photocatalytic water splitting but also provides an effective strategy for tuning the photocatalytic properties of 2D ferroelectric materials through ferroelectric switching.
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All authors Jubair Hossan Abir, Tauhidur Rahman, Md. Tanvir Khan, S.S.B. Pallab, Raihana Shams Islam, Saleh Hasan Naqib
Mesoscale and Nanoscale Physics
Process-Technology Co-optimization for 2D-FETs
Shao-Heng Yang, Jainil Dharmil Shah, Mayukh Das et al. (+15 more)
We present the first experimental machine learning (ML)-enabled Process-Technology Co-Optimization (PTCO) framework for optimizing 2D transition metal dichalcogenide (TMD) FET fabrication directly from statistically meaningful experimental data rather than pure simulation data. We first introduce a transition voltage metric, VTrans, to quantify the gate voltage required for off-to-on switching and reveal its direct correlation with subthreshold swing (SS), highlighting an overlooked switching characteristic that governs both off-state and on-state performance. By integrating automated metric extraction, multi-objective recipe ranking, and predictive modeling, our framework uncovers hidden process-performance correlations and predicts the performance of unexplored fabrication recipes from limited experimental data. Experimental validation shows close agreement with ML predictions, thus demonstrating the framework's ability to efficiently guide gate stack optimization through iterative experimental feedback.
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All authors Shao-Heng Yang, Jainil Dharmil Shah, Mayukh Das, Yuanqiu Tan, Hao-Yu Lan, Hsing-Chien Chien, Himani Jawa, Shalini Tripathi, Marco Antonio Villena, Xiangyu Wu, Daire Cott, Kaustav Banerjee, Pierre Morin, César Javier Lockhart de la Rosa, Gaurav Thareja, Dennis Lin, Joerg Appenzeller, Zhihong Chen
Statistical Mechanics
BKT-like Correlation Scaling and Twist Responses in a One-Dimensional Fractional $U(1)$ Ginzburg–Landau Model
Hitomi Endo and Michikazu Kobayashi
We study a one-dimensional fractional $U(1)$ Ginzburg–Landau model whose quadratic part has
Fourier multiplier $|k|^\sigma$, focusing on the marginal case $\sigma=1$. This dispersion yields logarithmic
spin-wave fluctuations, suggesting BKT-like behavior despite the one-dimensional setting. We sample the
equilibrium Gibbs measure using
stochastic Gross–Pitaevskii dynamics and analyze correlation functions, dimensionless ratios, effective exponents, and twist responses. The correlation function shows a low-temperature algebraic branch with a temperature-dependent exponent, while the high-temperature regime exhibits a nonlocal-kernel-induced tail consistent with $C(r)\sim r^{-2}$. The correlation and Binder ratios are nearly size independent at low temperature and collapse with the BKT-type variable $(T-T_{\rm BKT})(\log L)^2$; finite-size effects set in around $T\simeq0.35\text{--}0.4$, consistent with $T_{\rm BKT}\simeq0.35$. Unlike the two-dimensional XY model, twist responses do not yield a finite helicity modulus: the ordinary linear-response quantity grows with system size, whereas the cusp twist response scales as $L^{-\eta(T)}$, like the squared zero-mode order parameter. Thus, the transition is BKT-like in correlation scaling, but lacks a universal helicity-modulus jump.
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Strongly Correlated Electrons
Correlation-Driven Nonlinear Magnetoelectric Response in an Altermagnet: A Dynamical Mean-Field Study
Robert Peters and Jun Ōiké
We investigate the optical nonlinear magnetoelectric effect (NMEE) in a strongly correlated altermagnet using dynamical mean-field theory. Unlike effective band descriptions with an imposed
spin splitting, our approach determines the altermagnetic order, electronic spectrum, and optical nonlinear response self-consistently. We find that the NMEE is finite in the altermagnetic phase and vanishes in the paramagnetic phase. Its frequency dependence reflects the
spin-resolved spectral structure and provides an estimate of the characteristic altermagnetic
spin-splitting scale. Interaction and temperature tuning produce qualitatively different behavior: at low temperature, reducing the interaction strength toward the interaction-driven
magnetic phase boundary enhances the response, whereas increasing the temperature suppresses it and drives it to zero above the critical temperature. These results establish the optical NMEE as a probe of correlated altermagnetic order and suggest that tuning parameters such as pressure, strain, or chemical substitution toward an interaction-driven phase boundary may provide a promising route to maximizing the response.
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Mesoscale and Nanoscale Physics
Narrow-Sense Type-III Dirac Cones and Additional Flat Lines on a Honeycomb Lattice with Anisotropic Next-Nearest-Neighbor Hoppings
Keita Kishigi and Yasumasa Hasegawa
Critically tilted Dirac cones have attracted considerable
attention because of their unconventional electronic properties in two-dimensional massless Dirac-
fermion systems. Among them, the narrow-sense type-III Dirac cone is characterized by a flat dispersion along the direction connecting the two Dirac points. Using a tight-binding model on a single-orbital honeycomb
lattice, we demonstrate that narrow-sense type-III Dirac cones can be realized by tuning anisotropic next-nearest-neighbor hoppings. Type-I and type-II Dirac cones emerge on either side of the critical point, enabling a systematic investigation of the electronic properties across the type-I, narrow-sense type-III, and type-II regimes. We further find that the present model exhibits additional flat lines in momentum space whose energy coincides with the Dirac-point energy at the narrow-sense type-III critical point. This band structure produces a pronounced enhancement of the density of states at the
Fermi energy and, consequently, a substantial enhancement of the electronic specific heat compared with that expected for an ideal narrow-sense type-III Dirac cone. Our results show that the honeycomb
lattice with anisotropic next-nearest-neighbor hoppings provides a simple platform for exploring unconventional thermodynamic properties arising from the energy coincidence of narrow-sense type-III Dirac cones and additional flat lines at the
Fermi energy.
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Quantum Physics
The Fermionic Cohomology Problem on the Full Fock Space Is $\mathrm{QMA}_1$-Complete
Yibin Wang
Fermionic
cohomology detects zero-energy states of supersymmetric
Hamiltonians. Previous work showed that deciding nonzero
cohomology in an input-specified particle-number sector is $\mathrm{QMA}_1$-hard and belongs to $\mathrm{QMA}$. We study total
cohomology on the unrestricted full Fock space, where a NO instance must exclude zero-energy states in every sector and in their superpositions. We prove that this global problem is $\mathrm{QMA}_1$-complete. The input differential is an operator that raises
fermion number by one and squares to zero on the full Fock space. It is given as an exact list of local fermionic monomials, each involving at most $41$ modes. The reduction encodes each data site by one
fermion in a block of modes. Every sector violating this occupation rule has energy at least one. An exact
quantum verifier accepts a suitable witness with certainty on every YES instance, establishing containment with perfect completeness. We also prove $\mathrm{QMA}_1$-completeness for the problem in an input-specified particle-number sector. Its hard instances use $30$-mode terms and admit a one-dimensional block-chain realization.
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