Astrophysics of Galaxies
Evolution of Chemistry in the envelope of HOt corinoS (ECHOS). III. Sulphur chemistry in the Class 0 objects HH 212 and NGC 1333 IRAS 4A
P. Fernández-Ruiz, A. Fuente, G. Esplugues et al. (+7 more)
Our goal is to find chemical diagnostics to determine the physical conditions in protostellar envelopes and help establish the development of matter during the formation of a low-mass
star, as well as investigating a possible variation of sulphur depletion during the
star formation process at the scale of the cold envelope. With observations with the Yebes-40m and IRAM-30m
telescopes, we estimate column densities of sulphur-bearing species in the Class 0 objects HH212 and NGC1333 IRAS4A. A neural emulator of the chemical code Nautilus is used to constrain the chemical time, density, gas temperature,
cosmic ray ionization rate, and sulphur elemental abundance in the cold envelope of these objects. We compare the resulting abundances of these species with those towards the Class 0 object B335. While sulphur-bearing species containing carbon chains are between 3 and 7 times more abundant in B335 than in the other two objects, sulphur
oxides and nitrogen-bearing species are 3 times more abundant in NGC1333 IRAS4A. Our chemical modelling shows that, while the chemistry of HH212 and NGC1333 IRAS4A is well reproduced considering a gas temperature of 25 K and a sulphur depletion of a factor of 100 in their envelopes, significant differences are found in their average density and
cosmic ray ionization rate. Comparing with similar studies in pre-
stellar and protostellar cores, we derive an increase in the SO/CS and SO$_2$/C$_2$S ratios of about two orders of magnitude and a potential decrease in the HCS$^+$/CS ratio of a factor of 10 in the transition from the pre-
stellar to the Class 0 phase. Sulphur compounds are good evolutionary tracers of the pre- to protostellar phase transition, with oxygen-bearing species being more abundant than those containing carbon in the evolved sources. Nonetheless, sulphur depletion in the cold envelope of Class 0 objects remains similar to that in starless cores.
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All authors P. Fernández-Ruiz, A. Fuente, G. Esplugues, D. Navarro-Almaida, P. Riviére-Marichalar, T. Alonso-Albi, M. Rodríguez-Baras, A. Asensio Ramos, C. Westendorp Plaza, L. Moral-Almansa
Soft Condensed Matter
Pattern formation in nonlinear dynamics of nematic liquid crystals above the flexoelectric instability threshold
E.S. Pikina, E.I. Kats, A.R. Muratov et al. (+1 more)
For many decades, researchers have been studying various types of electro-hydrodynamic instabilities in
liquid crystals. A significant amount of experimental data has been collected, however, the theoretical interpretations of the results typically rely on linear analysis. In response to this limitation, we investigate the nonlinear stage of the flexoelectric instability in nematics, focusing on
liquid crystals with a negative anisotropy in their dielectric permittivity and electrical conductivity. We base our analysis on a comprehensive set of nonlinear electro-hydrodynamic equations for these nematics influenced by an external alternating electric field. The equations predict an instability that is driven by the flexoelectric effect. In order to examine the peculiarities of this phenomenon, we use a model that was proposed in our previous publications, Refs. [1,2], which allows us to perform numerical simulation of nonlinear dynamics. We examine patterns that are formed above the instability threshold. Through numerical simulations, we have identified static and dynamic patterns that occur over a timescale that is much longer than the period of the external electric field. The static patterns are one-dimensional structures and dynamic patterns are standing or traveling one-dimensional waves. The type of the realized pattern depends on the material and experimentally controlled parameters. We found that the standing waves are stable with respect to small transverse perturbations, whereas the propagating waves are unstable. We present a Ginzburg-Landau-like phenomenology that applies near the instability threshold. This approach allows us to rationalize our numerical findings with a few parameters.
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All authors E.S. Pikina, E.I. Kats, A.R. Muratov, V.V. Lebedev
Mathematical Physics
Time Averages for the Vortex Model and Stroboscopic Ergodic Averages
Emanuele Caglioti and Marco Cecchini
We consider the
vortex model on the plane, focusing on the case of
vortices with the same sign and, for simplicity, assuming all
vortices possess equal circulation. In particular we are interested at the time average of the vorticity density, i.e. the empirical measure associated to the
vortices. We
conjecture that, for a.e. initial data, the time average of the empirical density is radial. We prove the result for N=3
vortices by exploiting the integrability of the system. For N > 3
vortices we motivate the
conjecture by transforming the problem into the independence of ergodic stroboscopic averages from initial data along a single trajectory, when using a suitable rotation angle as the independent variable instead of the time variable.
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Quantum Physics
Enhancing Nonreciprocity through Squeezing-Induced Symmetry Breaking
B.-B. Liu, D.-Y. Wang, J. Tang et al. (+4 more)
Reservoir engineering enables unidirectional energy and signal flow. We establish squeezing-induced
symmetry breaking between two cavities as a guiding principle for exponentially amplifying reservoir-mediated nonreciprocity. Rather than a simple scaling of the coupling, this mechanism strategically redistributes the squeezing resources to relax experimental requirements, as single-cavity squeezing alone demands a much larger squeezing strength. Moreover, reservoir squeezing does not alter the system
symmetry, but reshapes the noise correlations and thereby changes the system dynamics. The proposed mechanism improves the performance of the
quantum battery by several orders of magnitude, including stored energy, charging power, and ergotropy, with the analytical expressions provided. Extending to the optical isolation, we observe a second-order exponential enhancement of the output signal. Our results open a new avenue for nonreciprocal
quantum information processing and nonreciprocal
quantum device design.
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All authors B.-B. Liu, D.-Y. Wang, J. Tang, Gang Chen, H. Jing, Shi-Lei Su, F. Nori
Materials Science
Atomic Cluster Expansion Potentials for Screw Dislocations in BCC Refractory Metals
Lei Zhang and Francesco Maresca
Accurate atomistic modeling of screw dislocations in body-centered cubic (bcc) metals remains challenging because their plasticity is governed by a complex dislocation glide behavior due to their compact three-fold symmetric core structure and a strongly temperature-dependent flow stress induced by the large Peierls barrier. In the context of group 6 (V, Nb, Ta) and group 5 (Mo, W) refractory metals (RMs), both classical interatomic potentials and some machine learning potentials consistently fail to reproduce density functional theory (DFT) Peierls barriers and the glide plane. Here, we developed an array of atomic cluster expansion (ACE) potentials for these RMs by extending an existing DFT database. The developed ACE potentials significantly improve the description of screw dislocation properties, achieving near-DFT accuracy for Mo and W and substantial improvement for V, Nb, and Ta. The results show that transferability to screw dislocation behavior depends sensitively on both database composition and element-specific energetics, and that achieving a single-humped Peierls barrier alone is not a sufficient validation metric for accurate prediction of dislocation glide. For Nb, Mo, and W, the developed ACE models also enable reliable calculation of kink-pair activation enthalpies, which are well described by both Kocks' law and a line-tension model.
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Quantum Physics
GsOQDC: A GUI-Driven Interactive Framework for End-to-End Simulation of Optical Quantum Data Centers
Seyed Navid Elyasi, Sima Bahrani, Rui Wang et al. (+3 more)
We present GsOQDC, an open-source graphical framework integrating optical-network design, distributed
quantum-
circuit compilation, scheduling, and DES-based remote-gate simulation, enabling end-to-end cross-layer evaluation of
entanglement-resource dynamics and system-level performance in Optical
Quantum Data Centers.
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All authors Seyed Navid Elyasi, Sima Bahrani, Rui Wang, Dimitra Simeonidou, Paolo Monti, Rui Lin
Optics
Universal Design Path for Optomechanical Crystals and One-dimensional Photonic Crystals
Berke Demiralp, Nien-Hsuan Lee and Eva M. Weig
We have shown a pattern that connects the refractive index, area and the cavity modes of the optomechanical
crystals (OMCs) by the same order function. By keeping the fundamental and second cavity modes within a range of -+16 nm and -+23 nm we have shown the link between the design area of the OMC and the refractive index of the material, by keeping the design area same we have shown the link between the refractive index and the cavity mode wavelength and by keeping the refractive index the same, we have shown the link between the cavity mode wavelength and the design area. We have performed simulations for 2 different OMC designs and 10 different refractive indices (9 different materials) to prove the first two claims and we have performed both simulations and experiments on a 3C-SiC OMC, which resulted as 100 nm shift of the second cavity mode, to prove the last claim. Our findings prove that a universal design for optomechanical
crystals is possible, making the transition to different material bases easier to exploit their specific properties, suggesting a path to commercialize such devices for hybrid
quantum technologies and having flexibility of tuning such devices for their own relative applications.
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Nuclear Theory
Dipolar flow of identified hadrons at mid-rapidity using transport models
Abhisek Praharaj, Aradhana Panday, Sandeep Chatterjee et al. (+1 more)
We report a transport model study of the rapidity even component of dipolar flow, $v_{1}^{\mathrm{even}}$, for identified charged
hadrons at mid-rapidity in Au+Au collisions at $\sqrt{s_{NN}} = 7.7-200$ GeV. The analysis is performed using the AMPT model. In addition, HIJING model is used to quantify residual non-flow contributions in $v_{1}^{\mathrm{even}}$. The $v_{1}^{\mathrm{even}}$ of identified
hadrons ($\pi$, $K$, and $p$) shows no significant difference between particles and anti-particles at $\sqrt{s_{NN}} = 200$ GeV. However, a clear splitting between
proton and anti-
proton $v_{1}^{\mathrm{even}}$ develops with decreasing beam energy, while no corresponding difference is observed for
mesons ($\pi^{\pm}$ and $K^{\pm}$). These results indicate that the
proton-antiproton difference in $v_{1}^{\mathrm{even}}$ is sensitive to
baryon transport and antibaryon annihilation in the hadronic medium. Our study highlights the potential of identified-particle $v_{1}^{\mathrm{even}}$ measurements at RHIC Beam Energy Scan energies as a novel probe of
baryon stopping and the
evolution of the hadronic medium.
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All authors Abhisek Praharaj, Aradhana Panday, Sandeep Chatterjee, Md Nasim
Strongly Correlated Electrons
Weak-coupling tensor cross interpolation impurity solver for nonequilibrium dynamical mean-field theory
Shuta Matsuura, Hiroshi Shinaoka, Philipp Werner et al. (+1 more)
Simulating nonequilibrium
quantum many-body systems remains a major challenge due to the exponential growth of the computational complexity with real time. Here we implement a nonequilibrium
impurity solver based on the weak-coupling expansion and the tensor cross interpolation (TCI), and apply it to nonequilibrium dynamical mean-field theory (DMFT). The method approximates the integrands of the high-dimensional integrals arising in the weak-coupling expansion in a tensor-train form, enabling efficient evaluations without
stochastic sampling and thereby mitigating the sign problem affecting continuous-time
quantum Monte Carlo (CT-QMC) methods.
Benchmark calculations for an exactly solvable nonequilibrium
impurity model agree well with the exact results and reveal a low-rank structure of the integrands. When applied to interaction-quench problems in the half-filled Hubbard model, the method reproduces fast thermalization at a critical interaction strength with accuracy comparable to CT-QMC. Away from half filling, where the sign problem becomes even more severe, the present approach remains well controlled, revealing a crossover instead of a sharply defined fast thermalization point in the 3/4-filled case. The solver can also be applied to steady-state DMFT problems, yielding accurate spectral functions in the metallic regime without analytic continuation.
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All authors Shuta Matsuura, Hiroshi Shinaoka, Philipp Werner, Naoto Tsuji
Disordered Systems and Neural Networks
Dependence of charge separation efficiency on the exciton-charge transfer offset and Gaussian disorder in organic solar cells
Maik Schwuchow, Carsten Deibel and Angela Thränhardt
State-of-the-art organic
solar cells increasingly rely on low-offset
semiconductor blends, challenging the traditional requirement of a large energetic driving force for efficient charge separation. In these systems, the energetic offset $\Delta E_{\mathrm{LE-CT}}$ between local
exciton (LE) and charge-transfer (CT) states approaches the thermal energy, making
exciton-CT hybridization and thermal repopulation of the
exciton level critical to device performance. In this work, we directly compare a macroscopic two-state rate model with three-dimensional kinetic Monte-Carlo (kMC) simulations to investigate microscopic charge separation dynamics and the role of Gaussian energetic disorder. We demonstrate that in the absence of disorder, the analytical rate model accurately reproduces kMC predictions for the whole range of $\Delta E_{\mathrm{LE-CT}}$. Specifically, the macroscopic model successfully explains horizontal shifts in the internal
quantum efficiency curves that arise depending on how the energetic offset is physically realized in the constituent molecules. We show that these variations can be captured entirely through the ratio of degeneracies of the LE and CT states, respectively. Introducing Gaussian energetic disorder into the kMC simulation reveals a distinct crossover behavior depending on $\Delta E_{\mathrm{LE-CT}}$. While disorder is mostly detrimental at large offsets, it can significantly boost efficiency at intermediate and low offsets. Thermalization of charge carriers within the disorder-broadened density of states creates an effective driving force allowing charge separation even at zero or negative energetic offsets.
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Quantum Physics
Quantum machine learning models for graphs
Frédéric Sauvage, Pranav Kalidindi, Frederic Rapp et al. (+1 more)
Geometric Machine Learning (GML) successes have been achieved through the thorough study and design of new equivariant neural networks. In comparison,
geometric quantum machine learning (GQML) models lack such a detailed understanding and, despite already several proposals, a unifying perspective on their design remains elusive. In this work, we focus on GQML models for graph problems that showcase a lot of structure and still remain frontier in machine learning. For the case when n-node graphs are encoded in n-
qubit states, we provide a comprehensive characterization of their constituents. Taken together, these furnish us with a toolbox for the design of
quantum graph models, and we further probe its benefits including the natural integration with classical models, generalization of known GQML models (sometimes extending their expressivity at virtually no cost), and straightforward classical pre-training strategies. The latter two features are demonstrated in dedicated numerical experiments.
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All authors Frédéric Sauvage, Pranav Kalidindi, Frederic Rapp, Mart{\i}n Larocca
Optics
Near-Field Characterisation of Guided Modes in WS2 Nanobeams and Quasi-Bulk Crystals
Zara S. Taylor, Luke M. Hallacy, Xuerong Hu et al. (+7 more)
The exceptionally high in-plane refractive index, low sub-bandgap absorption, and strong optical anisotropy of WS2 make it a promising material platform for next-generation integrated
circuits for nanophotonics. Its layered van der Waals structure further enables heterogeneous integration with silicon photonics and emerging two-dimensional optoelectronic materials. However, despite increasing interest in the waveguiding properties of WS2, experimental studies of wavelength-dependent modal confinement and attenuation remain limited. Additionally, though the extinction coefficient of WS2 is expected to be near-negligible beneath the bandgap, reported values span orders of magnitude, leading to large uncertainty in predicted modal decay lengths and wafer-scale integration feasibility. To resolve these ambiguities we perform hyperspectral cavity-enhanced imaging, determining high-resolution upper and lower bounds on the extinction coefficient of WS2 within the visible-NIR edge. We further employ scattering-type scanning near-field optical microscopy (s-SNOM) to probe TE0, TM0, and higher-order modes in both quasi-bulk and nanobeam WS2 waveguides across the 800-1400 nm spectral range, enabling identification of mode-specific trends in wavevector dispersion and loss. This work simultaneously assesses s-SNOM as a probe of waveguide performance, and we find that while absolute loss values depend on measurement geometry, s-SNOM reliably captures relative modal trends and provides upper bounds on propagation loss, supporting its use as a diagnostic tool for anisotropic waveguides. We further identify significant artefacts in nanobeam measurements arising from transverse interference and spatial sampling effects when the structure size approaches the excitation wavelength, which can shift extracted effective indices by up to 0.25.
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All authors Zara S. Taylor, Luke M. Hallacy, Xuerong Hu, Oliver T. Williams, Simone Strohmair, Fabian Felixberger, Alexander J. Knight, Timothy Chester-Parsons, Luke R. Wilson, Alexander I. Tartakovskii
Instrumentation and Detectors
In-Situ Polarimetry in Collimated Magneto-Infrared Spectroscopy System
Zeping Shi, Wenbin Wu, Zhiwei Zhang et al. (+14 more)
Magneto-infrared spectroscopy under strong
magnetic fields provides a powerful probe of Landau quantization and field-induced collective excitations, yet its full potential has long been constrained by the lack of in-situ polarization control, because the highly divergent infrared beam propagating through narrow light tubes undergoes multiple wall reflections, leading to severe polarization degradation. Here we report a collimated magneto-infrared spectroscopy system that integrates continuous in-situ polarimetry. The system employs incident and exit collimation chambers forming a Kepler type optical architecture, which converts the large-aperture FTIR output into a low-divergence beam and strongly suppresses multi-reflection trajectories inside long gold-plated light tubes, thereby enhancing both optical throughput and polarization fidelity. A remotely controlled polarization module, consisting of an automated linear polarizer and a switchable Fresnel rhomb positioned entirely outside the high-field region, enables continuous in-situ tuning between linear, circular, and arbitrary elliptical polarization states without thermal cycling, manual realignment, or breaking
vacuum. Interchangeable compact focusing modules further support Faraday and Voigt geometries in both transmission and reflection experiments within a 50 mm magnet bore, providing efficient beam focusing and signal collection while maintaining polarization fidelity. The setup achieves a minimum root-mean-square noise of 0.0033%, an average noise of 0.0082%, and a linear polarization extinction ratio up to 40:1. We demonstrate the capability through continuous in-situ linear polarimetry and broadband circular polarimetry in the magneto-infrared spectroscopy of various single
crystals. This platform establishes a robust experimental framework for in-situ polarization-resolved magneto-infrared spectroscopy.
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All authors Zeping Shi, Wenbin Wu, Zhiwei Zhang, Yuhan Du, Chenyao Xu, Congming Hao, Xiangyu Jiang, Xin Chen, Guangyi Wang, Mingsen Zhou, Chunhui Pan, Wei Lu, Hao Shen, Haifeng Pan, Zhenrong Sun, Junhao Chu, Xiang Yuan
Quantum Physics
Leakage Mobility and Passive Leakage Removal in Transmons with Tunable Couplers
Taneli Tolppanen, Gonzalo Martín-Vázquez, Sasu Tuohino et al. (+1 more)
Qubit leakage is a noticeable source of errors for
quantum computing. In
quantum processors, leakage excitations traveling between
qubits generate correlated errors and perturb gate implementations. Leakage mobility can also be utilized for creating dedicated leakage removal pathways and removal units. To quantitatively characterize leakage mobility and to guide better design of processor architectures, we study here leakage dynamics in transmons with tunable couplers through numerical and analytical methods. Even if the couplers are tuned to cancel the single-excitation exchange or the ZZ interaction, the leakage hopping rates still persists in the range of 0.8-10 MHz due to transmon nonlinearity. In typical operation regimes, however, transmon frequency detuning localizes leakage excitations. The next-nearest-neighbor transmons can be still be near-resonant opening leakage tunneling channels. To suppress longer-range hopping, we find that the frequency spread of the next-nearest-neighbor transmons needs to be in the range of 1-4 MHz. Utilizing leakage mobility, we propose two passive leakage removal units. One is based on a tunable coupler and a pumped transmon, and another on a junction readout scheme. Based on realistic experimental parameters, our results on selectively mobilizing or localizing leakage excitations are readily applicable in superconducting
quantum devices.
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All authors Taneli Tolppanen, Gonzalo Martín-Vázquez, Sasu Tuohino, Matti Silveri
Mesoscale and Nanoscale Physics
Facet-selective ballistic supercurrent in a weak topological insulator
Prasanna Rout, Ankit Khola, Lalit Pandey et al. (+9 more)
Topological superconductivity is widely pursued by inducing superconducting correlations in topologically protected boundary states. In two dimensions, this strategy has been realized using one-dimensional topological edge modes, but in three-dimensional
crystals, spatially separated surface supercurrents confined to selected facets have not yet been achieved. Here we demonstrate facet-selective ballistic supercurrent in Josephson junctions based on the weak topological
insulator ZrTe<sub>5</sub>. Superconducting
quantum interferometry reveals SQUID-like critical current oscillations with flux-
quantum periodicity, establishing that the supercurrent is spatially concentrated on specific crystallographic facets that host gapless topological surface states. Rotating the
magnetic field yields markedly distinct interference patterns, linking the supercurrent distribution to the underlying bulk
topology. The exponential temperature dependence of the critical current and triangular interference lobes provide signatures of ballistic transport due to high-transmission topological channels. These results establish weak topological
insulators as a platform for facet-resolved superconducting devices and higher-order topological superconductivity.
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All authors Prasanna Rout, Ankit Khola, Lalit Pandey, Paolo Sessi, Xiaochun Huang, Ivo Cools, S. Galeski, Matthias Bode, Johan Åkerman, Floriana Lombardi, Thilo Bauch, Saroj P. Dash
Solar and Stellar Astrophysics
Unravelling the nonthermal emissions from the quiet solar corona with the SKA
Surajit Mondal, Divya Oberoi, Rohit Sharma et al. (+4 more)
Investigation of the nonthermal emissions from the quiet
solar corona has been rather limited. This primarily stems from the fact that the emission is expected to be quite weak and very high dynamic range images are required to detect such emissions. Although, the few detections of the nonthermal emissions have all come from the
radio band, the past observations had several issues, the most important being the low image fidelity and lack of simultaneous broadband observation capability. Recent observations have been able to tackle many of these prior difficulties using modern instrumentation, and have produced multiple interesting results. In spite of these improvements, multiple challenges remain. For example, most of the recent investigations were only able to focus on the brightest of these events, due to rather poor spectroscopic snapshot PSF of the instruments. The SKA, with its excellent sensitivity as well as its exquisite spectroscopic snapshot PSF would be a game-changer in this field. It would not only allow us to detect and characterise these emissions in Stokes I, but would also allow us to investigate their polarisation properties as well. The high angular resolution offered by the SKA will allow a unique association of the detected
radio transients with their thermal counterparts. This would enable us to investigate the thermal-nonthermal energy partition even for these rather weak transient emissions, which in turn would allow validation of particle acceleration and
magnetic reconnection theories in a regime vastly different from that done previously. In addition, characterization of the nonthermal emissions of these weak coronal transients may also provide a new probe to understand how energy is transferred from the photosphere and dumped into the corona, and thus serve as a new tool to tackle the coronal heating problem.
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All authors Surajit Mondal, Divya Oberoi, Rohit Sharma, Peijin Zhang, Devojyoti Kansabanik, Xingyao Chen, Eduard Kontar
Nuclear Theory
Elastic deuteron-deuteron scattering in the ${}^5S_2$ channel within Nuclear Lattice Effective Field Theory
Helen Meyer, Serdar Elhatisari, Fabian Hildenbrand et al. (+1 more)
We calculate low-energy deuteron-deuteron scattering in the
spin-quintet $^{5}S_2$ channel using
nuclear lattice effective field theory. The calculation combines
chiral interactions at next-to-next-to-next-to-leading order, implemented through wavefunction matching, with the adiabatic projection method. Because the radial cluster basis develops small norm-
matrix eigenvalues at large Euclidean projection time, we investigate two stabilization procedures: Tikhonov regularization and projection onto well-resolved norm eigenmodes. The two procedures yield consistent Coulomb-subtracted phase shifts within their statistical and numerical uncertainties. A Coulomb-modified effective-range analysis gives ${}^5a_{dd} = (11.99 \pm 0.22)$ fm and ${}^5r_{dd} = (3.44 \pm 0.79)$ fm. The phase shifts are more negative, and the scattering length is substantially larger than in previous calculations, corresponding to a stronger effective repulsion in the $^{5}S_2$ channel. These results provide a first
nuclear-
lattice benchmark for deuteron-deuteron scattering and establish a starting point for future coupled-channel calculations of the deuteron-induced reactions relevant to big-bang nucleosynthesis.
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All authors Helen Meyer, Serdar Elhatisari, Fabian Hildenbrand, Ulf-G. Meißner
Strongly Correlated Electrons
Quantum Oscillations of $\mathrm{Sr}_2\mathrm{RuO}_4$ under c-Axis Uniaxial Stress
Fabian Jerzembeck, Maximilian T. Pelly, Helge Rosner et al. (+7 more)
Uniaxial stress has now been widely used to study correlated electron materials. However,
Fermi surface-resolved experimental data on the
evolution of the electronic structure under piezoelectrically applied stress are sparse, with no reports of de Haas-van Alphen (dHvA) effects under uniaxial stress. Here we present dHvA measurements under $c$-axis uniaxial stress on the unconventional
superconductor $\mathrm{Sr}_2\mathrm{RuO}_4$. This allows us to study the
evolution of the electronic structure directly and to gain insight into the contradicting behavior of the predicted enhancement of the electronic density of states and the observed suppression of $T_\text{c}$. We are able to follow all
Fermi surfaces for stress up to $-1.8$~GPa and find that the cross-sectional areas of the hole-like $\alpha$ sheet increase and electron-like $\beta$ sheet decrease. At the same time, the area of the electron-like $\gamma$ sheet increases. Therefore, in contrast to in-plane uniaxial stress, charge transfer is the mechanism for approaching the electron-to-hole Lifshitz transition and the associated Van Hove singularity. Additionally, we find that the effective masses on all three
Fermi sheets are slightly enhanced as the Lifshitz transition is approached. We compare the dHvA results with
quantum oscillations in the magnetostriction and band structure calculations, and find good agreement. At a more general level, our findings show that
quantum oscillation measurements under uniaxial stress, combined with band-structure calculations, offer a promising new route for studying
quantum materials.
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All authors Fabian Jerzembeck, Maximilian T. Pelly, Helge Rosner, Edgar Abarca Morales, Naoki Kikugawa, Dmitry A. Sokolov, Andrew P. Mackenzie, Andreas W. Rost, Elena Hassinger, Javier F. Landaeta
General Relativity and Quantum Cosmology
Thermodynamic-Geometric Phase Transition and Gravitational-Wave Quasinormal Modes of Schwarzschild Black Holes in $f(Q)$ Gravity: An RVB-Residue Approach
Wen-Xiang Chen
We construct a residue-based framework connecting the thermodynamic geometry of a Schwarzschild-type black hole in $f(Q)$
gravity with its gravitational-wave quasinormal-mode spectrum. The analysis is based on the symmetric teleparallel formulation of
gravity, in which the gravitational field is encoded by the nonmetricity scalar $Q$ rather than by
curvature or torsion. For the Schwarzschild branch, the Robson–Villari–Biancalana (RVB) method gives the Hawking temperature through the simple-pole residue of the inverse blackening function. We show explicitly that the same residue also controls the logarithmic monodromy of the tortoise coordinate near the event horizon, and therefore enters the ingoing quasinormal-mode boundary condition. In the strict general-relativistic Schwarzschild limit the heat capacity is negative and finite, the one-dimensional Ruppeiner geometry contains no intrinsic
curvature singularity, and no genuine thermodynamic phase transition occurs. In the extended $f(Q)$ state space, however, the modified horizon function and the effective Wald
entropy generate a non-trivial thermodynamic Hessian. Its degeneracy condition coincides with singular behavior of the thermodynamic
curvature and is reflected in the quasinormal-mode spectrum through shifts of the
photon-sphere frequency, Lyapunov exponent, damping time, and near-horizon monodromy. This gives a precise statement of the internal relation between thermodynamic-
geometric phase structure and gravitational-wave ringdown: both are different projections of the same analytic structure of the corrected black-hole metric.
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Mesoscale and Nanoscale Physics
Spinterface-like mechanism of the chirality-induced spin selectivity in donor chiral-bridge acceptor complexes
Subhajit Sarkar, Oliver L. A. Monti and Yonatan Dubi
The chirality-induced
spin selectivity (CISS) effect has been invoked to explain recent reports of differences in the time-resolved EPR signals between
chiral and achiral molecules. However, the microscopic origin of these differences and their connection to CISS remains contested, particularly since these systems lack a metal interface. Here we introduce an intramolecular spinterface-like mechanism that naturally arises within donor-
chiral bridge-acceptor (D–$\chi$B–A) complexes and quantitatively reproduces experimentally reported observed
spin polarization in time-resolved EPR studies. In our two-electron Lindblad model, the photoexcited charge-transfer electron traversing the
chiral bridge exchanges with the residual donor electron, which acts as a localized
magnetic moment analogous to an induced
magnetic moment on an electrode surface. The resulting through-bridge charge current produces an effective solenoidal field at the donor–bridge interface, breaking
spin degeneracy and directional
symmetry, thus enabling
spin-selective transport without invoking intrinsic
spin-orbit coupling on the bridge. We show that the interplay between this current-induced field, donor thermalization (which breaks time-reversal
symmetry), and bridge
spin mixing yields tens-of-percent polarization over realistic experimental conditions and charge-transfer time scales, matching reported CISS signatures in triads and DNA hairpins. By explicitly resolving the dependence on solenoidal coupling strength, temperature, and
spin-mixing rates, the model identifies the regime in which internal spinterfaces can generate robust CISS-like
spin filtering. These findings demonstrate that CISS-like signals in isolated D–$\chi$B–A complexes are fully compatible with a spinterface mechanism, providing a unified conceptual framework for interpreting both device-based and molecule-internal CISS platforms.
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General Relativity and Quantum Cosmology
Spin-torsion interaction and geodesic bending
Sagar Kumar Maity and Amitabha Lahiri
The intrinsic
spin of
fermions induces torsion in spacetime, leading to an effective four-
fermion interaction. This affects the bending of null and timelike geodesics inside a
star with a spherically symmetric distribution of gravitationally dense fermionic matter of constant density. Our analysis shows an additional torsional contribution to the geodesic deflection, alongside the conventional
curvature-induced effect. This change depends on the
fermion number density, coupling constants of the different species of
fermions with different chiralities, and the temperature of the matter distribution. We have shown that the torsion-induced corrections to null geodesic bending remains very small for both low- and high-mass white
dwarfs, whereas significantly larger effects may arise in more compact astrophysical objects such as
neutron stars.
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Solar and Stellar Astrophysics
Constraining the model-based uncertainties of asteroseismic magnetic field measurements in red giants
L. Buchele, L. Bugnet, N. Muntean et al. (+1 more)
Magnetic fields inside red
giants are measured using shifts to the oscillation frequencies. However, in the asymptotic framework, converting a frequency shift into a radial
magnetic field strength requires knowing the global
magnetic sensitivity. This parameter (also called the core structure parameter) must be inferred from
stellar models, introducing a source of uncertainty. We seek to understand how the global
magnetic sensitivity depends on
stellar properties such as mass and
metallicity, and to quantify the model-based uncertainty on
magnetic field measurements. We also explore which
stellar properties are key to finding a precise and accurate estimate of the global
magnetic sensitivity. Using MESA models, we examine how the global
magnetic sensitivity changes with mass,
metallicity, and age. We then create a set of synthetic
stars and test how well we recover the sensitivity parameter. We consider different grid construction approaches and the choice of which observables are used in the fitting process. We find that the global
magnetic sensitivity shows a stronger dependence on mass for higher mass models and a stronger
metallicity dependence for lower
metallicity models. Our approach recovers the sensitivity parameter well, with an uncertainty of 10% when precise
metallicity measurements are used. We apply our method to
stars with existing
magnetic field measurements. In most cases, the dominant source of uncertainty remains observational, although precise modeling can significantly reduce the
magnetic field uncertainty for
stars with exceptional data. With careful fitting, models yield accurate values for the global
magnetic sensitivity. We recommend that future work obtain the global
magnetic sensitivity using both asteroseismic and high-quality spectroscopic data. Under these conditions, we recommend adopting a model-based uncertainty of 10% on the sensitivity parameter.
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All authors L. Buchele, L. Bugnet, N. Muntean, E. Hatt
Superconductivity
Collective phase modes in twisted $d$-wave superconducting bilayers
Yin Shi, Mengxian Zhao, Fei Yang et al. (+2 more)
Twisted cuprate
bilayers have been predicted to host high-temperature
chiral $d+id'$ superconductivity, originating from higher-order Josephson coupling processes. In such two-dimensional superconducting systems, long-wavelength fluctuations in the phase of the superconducting order parameter constitute gapless collective modes and therefore remain significant even at zero temperature. Here, we perform a theoretical analysis of the low-energy phase fluctuations in twisted $d$-wave superconducting
bilayers within a self-consistent harmonic approximation, systematically retaining Josephson coupling to all orders. We demonstrate that higher-order Josephson coupling processes lead to nontrivial modifications of the phase dynamics. The momentum-resolved summand of the relative-phase stiffness is nonzero even in the normal state because interlayer tunneling explicitly breaks the intralayer U(1)
symmetry, but its momentum integral vanishes for the continuum dispersion. The relative-phase stiffness is smaller in the $d+id'$ phase than in the $d$-wave phase, while the overall-phase stiffness has the opposite behavior. Furthermore, phase fluctuations strongly soften the Josephson
plasma frequency near a twist angle of $45^\circ$ and also substantially reduce the Josephson critical current.
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All authors Yin Shi, Mengxian Zhao, Fei Yang, Miao Liu, Sheng Meng
Quantum Physics
Overcoming the Speed-Fidelity Trade-off in Fast CZ Gates via Cyclic Control
Ze-An Zhao, Hai-Feng Zhang, Tian-Le Wang et al. (+10 more)
High-fidelity
quantum gates are essential for scalable
quantum computation. However, at short durations, short-timescale waveform distortions break the time-reflection
symmetry of control pulses, preventing the precise closure of cyclic
evolution. This mechanism renders conventional symmetric protocols intrinsically over-constrained. Conventional strategies typically rely on smoothing the pulse envelopes or
embedding the interaction pulse within a longer
qubit pulse to bypass short-timescale distortions, which inevitably leads to a persistent speed-fidelity trade-off. To overcome this limitation, we introduce a cyclic control strategy based on parameter-space expansion, which restores controllability by incorporating an additional degree of freedom. We experimentally demonstrate this approach in a superconducting controlled-Z gate, achieving robust suppression of coherent errors without increasing gate duration, reducing the average coherent error from 0.27% to 0.12% across multiple two-
qubit gates, as validated by cross-
entropy benchmarking. Our results establish a general route to fast, high-fidelity cyclic
quantum gates beyond the conventional speed-fidelity trade-off.
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All authors Ze-An Zhao, Hai-Feng Zhang, Tian-Le Wang, Xiao-Yan Yang, Peng Wang, Ren-Ze Zhao, Sheng Zhang, Zhi-Fei Li, Yuan Wu, Zi-Hao Fu, Sheng-Ri Liu, Peng Duan, Guo-Ping Guo
Earth and Planetary Astrophysics
Unveiling the Mysteries of Lightning: Exploring its fundamental Physical Processes with SKA-LOW
Brian M Hare, Sjoerd Bouma, Stijn Buitink et al. (+15 more)
Lightning is a surprisingly poorly understood phenomena. It consists of a wide variety of complex processes such as initiation, propagation, connection to ground, even emission of high-energy radiation. However, due to the extreme challenges in observing lightning at fast time scales, small spatial scales, and behind obscuring clouds, these processes are not well understood. In the past, interferometers such as the LOFAR
radio telescope have provided unique insight and discoveries into the physics of lightning. The new SKA-LOW being built in western Australia will provide unrivaled spectral bandwidth and sensitivity, which will be combined with high resolution resulting from large
antenna baselines. We will use SKA-LOW to observe lightning in order to explore its fundamental
plasma physics, such as how it initiates and propagates. SKA's high bandwidth will allow us to test how lightning emits VHF radiation, giving tremendous insight into precisely how the
plasma behaves. SKA's sensitivity will allow us to explore extremely faint lightning processes, such as the very first
radio emission from a lightning flash. Here, we detail the lightning physics that can be explored with SKA, as well as the observation strategy needed explore such physics.
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All authors Brian M Hare, Sjoerd Bouma, Stijn Buitink, Arthur Corstanje, Steve Cummer, Joseph Dwyer, Vital De Henau, Tim Huege, Philipp Laub, Ningyu Liu, Marten A.A. Lourens, Katie Mulrey, Anna Nelles, Olaf Scholten, Chris Sterpka, Karen Terveer, Paulina Ťureková, Keito Watanabe
Optics
Self-selected phase-matched second harmonic generation in nonlinear optical materials: from phenomenon to applications
Niklas Dömer, Tobias Hehemann, Felix Sauerwein et al. (+3 more)
Self-selected phase-matched second harmonic generation is introduced as an all-optical probe of refractive-index dispersion in birefringent nonlinear optical materials. Rather than requiring wavelength or angular tuning, the exposure with a spectrally broad, intense ultrashort pulse allows the material to self-select the fundamental spectral component that satisfies the type-I noncritical phase-matching condition. This produces a narrow peak in the second harmonic spectrum whose position is governed by the refractive indices and is therefore highly sensitive to material parameters that affect the optical dispersion. We demonstrate the application of this phenomenon for the optical inspection of stoichiometry and temperature gradients in technologically relevant lithium niobate, as well as composition inhomogeneities in newly grown lithium niobate-tantalate solid solutions. These results establish self-selected phase-matched second harmonic generation as a rapid, non-contact method for inspecting nonlinear optical materials, with potential relevance for bulk
crystals, wafers, and thin-film platforms.
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All authors Niklas Dömer, Tobias Hehemann, Felix Sauerwein, Sebastian Inckemann, Steffen Ganschow, Mirco Imlau
Mathematical Physics
On the Application of Poincare-Steklov Operators to the Problem of Resonant Scattering in a Cylinder
A.L Delitsyn
The resonant nature of scattering in a waveguide with two barriers is proven in the case of a sufficiently arbitrary deformation of the region between the barriers. The problem is considered as an interior boundary value problem with boundary conditions defined by a Poincare-Steklov operator. A spectral problem is considered whose
eigenvalue determines the resonant scattering frequency.
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Quantum Physics
Far-field spatial coherence driven by lossy objects: first-principles approach unifying scattering of quantum light and thermal emission
Alessandro Ciattoni
Far-field spatial coherence dictates the interference properties of scattered light and thermal emission. Traditionally, these phenomena are treated through disjointed paradigms: classical scattering descriptions assume cold objects lacking
quantum fluctuations, idealized
quantum scattering schemes ignore dissipation, and semiclassical fluctuational electrodynamics relies on phenomenological noise currents, precluding the consistent treatment of incident
quantum states. Here, we develop a first-principles framework based on the modified Langevin noise formalism to unify the scattering of
quantum light and the intrinsic thermal emission of finite dissipative objects. We demonstrate that the outgoing far-field spatial coherence separates into an algebraic superposition of two geometry-driven mechanisms, coupled by the global unitarity of the radiation-matter dynamics. The first mechanism, elastic scattering, acts as a non-
unitary spatial filter, mode-selectively attenuating and reshaping incident
quantum correlations. The second mechanism, thermal emission, originates from localized material dissipation and projects the object's absorption profile into the far field, providing a
quantum-vectorial derivation of the macroscopic van Cittert-Zernike
theorem. Applying this framework across optical regimes, we determine operational bounds for lossy
quantum photonics. Under chaotic thermal illumination, we analytically demonstrate thermal cloaking at
equilibrium and show that a passive sink casts a structured thermal shadow geometrically identical to a primary emitter. Under coherent illumination, we derive a thermodynamic phase diagram bounding macroscopic phase correlations, demonstrating that subwavelength nanostructures undergo substantial coherence degradation compared to bulk objects. Finally, under spatially entangled illumination...
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High Energy Physics (Phenomenology)
Charmonium-nucleon femtoscopy as a possible probe of the nucleon gravitational form factor
Ren Ejima, Daisuke Fujii and Mamiya Kawaguchi
We investigate the charmonium-nucleon interaction, focusing on its connection with the internal structure of the nucleon encoded in the gravitational form factors. To describe this interaction, we employ an effective potential based on the QCD multipole expansion within the leading chromoelectric dipole approximation. In this framework, the potential is expressed in terms of the energy and pressure distributions inside the nucleon. We first construct these distributions from the gravitational form factors fitted to
lattice-QCD data. The remaining model parameters are then fixed by requiring that the resulting $J/\psi$-$N$ potential reproduce the HAL QCD potential outside the short-distance region, as well as the scattering phase shift estimated from the HAL QCD data. Based on this potential, we evaluate the $J/\psi$-$N$ correlation function and further investigate the $\psi(2S)$-$N$ system. We then examine the sensitivity of these correlation functions to the nucleon $D$-form factor.
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General Relativity and Quantum Cosmology
Reframing of Information Geometry via Symmetric Teleparallel Gravity
Tatsuaki Wada
Information geometry has traditionally been formulated within the framework of Riemannian geometry and dual affine connections. This work aims to reframe the foundational structure of information geometry by introducing the
geometric machinery of symmetric teleparallel
gravity. By requiring both
curvature and torsion to vanish globally on the statistical
manifold, it is demonstrated that the fundamental properties of the information space can be entirely encoded in the non-metricity tensor. This approach clarifies the distinction between the general $\xi $-parameterized case and the $\theta$- or $\eta $-parameterized cases, which correspond to general symmetric teleparallel
gravity and its coincident gauge, respectively. Specifically, the $\theta$- or $\eta $-coordinates emerge as special coordinates in the coincident gauge, where the connection coefficients vanish.
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