Mathematical Physics
Quantum Vortices in a Boundary Layer: New Results and Perspectives
Sergei V. Talalov
Here, we investigate the motion of a thin circular
quantum vortex filament near the infinite planar surface. The fluid surrounding this surface moves with a non-zero velocity $\bf{v}$, which is parallel to the surface. We study the specific features of this
quantum system and show that they are quite suitable for the boundary layer theory. The developed model allows us to calculate the
vortex energy spectrum, $E = E({\bf p})$, where ${\bf p}$ is the total momentum of a
vortex ring. We have demonstrated that this function has complex non-trivial dependence on the velocity $\bf{v}$. It is stated that the inverse effective mass of a
vortex under consideration is of a tensorial nature. In certain
quantum states, the system shows the possibility of both negative and positive effective mass existing. This study employs a novel quantization method for classical closed
vortex filaments, developed by the author earlier.
Read the full abstract ▾
Quantum Physics
Scaled Caldeira-Leggett Dynamics: Deterministic Trajectories and the Classical Limit
S. V. Mousavi and S. Miret-Artés
The dynamics of an open
quantum system in the high-temperature regime of the Caldeira-Leggett model using a Bohmian
language is investigated. By expressing the density
matrix in polar form, generalized continuity and Hamilton-Jacobi equations are obtained. Thermal effects appear explicitly in the former, while they influence the latter only indirectly through an effective potential. Remarkably, the effective potential does not vanish in the classical limit and cannot, in general, be decomposed into simple additive
quantum and thermal contributions. Instead, it retains a nontrivial structure leading to a residual temperature dependence in the resulting dynamics. As a consequence, the resulting temperature-dependent-classical trajectories remain deterministic even in the presence of a thermal environment. This behavior contrasts with the
stochastic dynamics observed in the Langevin description and reflects the ensemble-based nature of the present approach. To further explore the
quantum-to-classical transition, a scaled version of the Caldeira-Leggett equation is introduced by scaling both the density
matrix and Planck constant through a quantumness parameter. This parameter takes the value one in the fully
quantum regime and smoothly approaches zero in the classical limit. Applications to Gaussian states demonstrate a gradual suppression of coherence and interference, governed jointly by thermal effects and the transition parameter.
Read the full abstract ▾
General Relativity and Quantum Cosmology
Superradiant Bose–Einstein condensates around Kerr black holes
Sen Guo, Lin Wen and Xiao-Xiong Zeng
Ultralight bosonic dark matter can accumulate around a rotating black hole, where superradiance amplifies the field until a macroscopic cloud forms. Whether such a cloud behaves as a Bose–Einstein condensate depends on the self-interaction, which earlier work has either retained on static backgrounds or dropped on the Kerr metric. Here we treat the two together. Starting from the Klein–Gordon equation with a quartic potential, we separate the linear problem into spheroidal and radial equations and solve them self-consistently, obtain the superradiant growth rate from the conserved Noether current, project the nonlinear term onto a single mode, and integrate the resulting Gross–Pitaevskii equation with a bordered Newton method at fixed particle number. Rotation modulates the self-interaction geometrically: the effective coupling carries a factor $\Delta(r)$ and therefore switches off at the horizon. Once the field is rescaled, the whole solution family depends on the single dimensionless parameter $\mathcal{N}=\lambda N$. We recover the hydrogenic spectrum of the gravitational atom and the $\alpha^{4\ell+5}$ scaling of the growth rate, and we obtain the exact relation $J_{z}=\hbar mN$, which receives no correction from the self-interaction. We find that the condensate is a
torus rather than a spherical shell, with its density vanishing identically on the rotation axis, and that the cloud is modified appreciably only for $\mathcal{N}\gtrsim10^{3}$.
Read the full abstract ▾
Quantum Physics
Adaptive Reconstruction of Bosonic Quantum States
Vasilisa Usova, Phila Rembold, Ian Yang et al. (+4 more)
Bosonic
quantum systems provide a hardware-efficient platform for
quantum information processing but remain challenging to characterise due to their large
Hilbert space and the high measurement cost of state
tomography. Existing approaches estimate the fidelity with respect to a single target state, making them unsuitable for applications in which physically equivalent states differ by phase space translations, rotations, or other transformations. Here, we introduce an adaptive reconstruction technique that estimates the fidelity with respect to a family of bosonic states while reconstructing the underlying Wigner function from a small number of measurements. The method combines a physics-informed parametric model with
Bayesian inference, bootstrap, and active learning to iteratively select the most informative phase space sampling points. We implement the approach on a
circuit quantum electrodynamics platform and
benchmark it on Schrödinger cat states with amplitudes $\alpha\in[1,3]$. The reconstruction yields reproducible fidelity estimates within a few minutes, remains robust to substantial displacements and rotations in phase space despite using a mismatched prior, and is sensitive to subtle state imperfections. We further compare the adaptive strategy with existing Wigner function sampling protocols experimentally, demonstrating the advantage of adaptive sampling for measurement-efficient fidelity estimation with respect to a family of cat states. Finally, we incorporate the reconstructed fidelity into the figure of merit used in a proof-of-principle closed-loop
quantum optimal control experiment, demonstrating the applicability of the method to autonomous optimisation of bosonic
quantum states.
Read the full abstract ▾
All authors Vasilisa Usova, Phila Rembold, Ian Yang, Marco Rossignolo, Simone Montangero, Samuele Tosatto, Gerhard Kirchmair
Superconductivity
Enhanced and robust superconductivity in La0.8Sr0.2NiO2 membranes compressed up to 210 GPa
Shu Cai, Yuqing Tian, Shengjun Yan et al. (+10 more)
The discovery of superconductivity in infinite-layer nickelate thin films has opened a new frontier for exploring unconventional
oxide superconductors beyond the copper
oxide family. However, the presence of substrate hampers investigations under very high pressure. Recently, this problem was circumvented by a study of freestanding Nd0.85Sr0.15NiO2 membranes, which revealed that superconducting transition temperature kept increasing as the pressure was ramped up to 91 GPa, without showing signs of saturation. Naturally, one wonders what would happen at even higher pressures. Here, we report that superconductivity in a freestanding La0.8Sr0.2NiO2 membrane persists under applied ultrahigh pressures up to 210 GPa. The superconducting transition onset temperature exhibits a continuous dome-like
evolution, increasing from 16 K at ambient pressure to a peak of 74.5 K at 146 GPa, and then gradually decreasing to 57.4 K at 210 GPa. Such robustness of superconductivity against ultrahigh pressure has not been observed in high-Tc
oxide superconductors before.
Read the full abstract ▾
All authors Shu Cai, Yuqing Tian, Shengjun Yan, Jinyu Zhao, Bo Hao, Jianfeng Zhang, Shuaihang Sun, Yang Ding, Qi Wu, Ho-kwang Mao, I. Bozovic, Yuefeng Nie, Liling Sun
Quantum Physics
Towards Tensor-Network SAT-Solvers for Quantum-Classical Workflows
Benjamin Zec, Lukas Schmidbauer, Maja Franz et al. (+1 more)
Integrated HPC/QC systems aim to combine classical high-performance computing with
quantum processors, but cannot be reduced to mechanisms for dispatching
quantum kernels. An integrated architecture must support aspects such as observability, which cannot be implemented using QPUs alone, as well as fallback execution and cost-aware decisions on whether to replace
quantum tasks with classical surrogates. Such mechanisms must be approximate or benefit from problem structure to soften the inescapable exponential classical worst-case complexity. In this work, we study tensor-network ground-state search, as such a surrogate, for optimisation problems. This combines key
quantum primitives with advanced classical simulation. It provides initial empirical indicators for surrogate selection criteria, and exposes end-to-end toolchain effects that may be missed when transformation steps are studied in isolation. We compare a native
polynomial unconstrained optimisation to-higher-order-Ising and a quadratised quadratic unconstrained binary optimization to-quadratic-Ising formulation for Max-3-SAT. Both are encoded as
matrix product operator and optimised using density
matrix renormalisation group approaches, with simulated annealing (SA) as classical performance baseline. Our results show that quadratisation is not a neutral transformation step: auxiliary variables and pairwise couplings substantially degrade solution quality relative to the native higher-order representation, while SA matches or outperforms DMRG across all tested instances. Since the optima of Boolean satisfiability (SAT)-derived problems are classical product states, DMRGs advantages dont materialise here. These findings suggest that surrogate selection in HPC/QC runtimes must be encoding- and instance-aware and provide empirical groundwork for informed decisions on fallback strategies and architecture co-design.
Read the full abstract ▾
All authors Benjamin Zec, Lukas Schmidbauer, Maja Franz, Wolfgang Mauerer
Mesoscale and Nanoscale Physics
Resolving High-Energy States of Interlayer Excitons in MoSe$_2$/WSe$_2$ Heterostructures
Chirag Chandrakant Palekar, Paulo E. Faria Junior, Tobias Manthei et al. (+8 more)
High-energy states of interlayer
excitons (IXs) in van der Waals
heterostructures remain largely unexplored despite their importance for understanding many-body interactions and nonlinear optical phenomena. Here, we use photoluminescence excitation (PLE) spectroscopy to resolve a Rydberg-like series of excited IX states in MoSe$_2$/WSe$_2$
heterostructures. We observe multiple PLE resonances below the intralayer
exciton energies, which we assign to the 2s-, 3s-, and 4s-like states of the IXs. These resonances are consistently observed across
heterostructures with different twist angles, indicating that the high-energy state spectrum is only weakly affected by the twist angle. Wannier-
exciton calculations incorporating screened Coulomb interactions reproduce the overall energy scale and qualitative trends of the measured Rydberg-like series, supporting the assignment of the observed resonances. Our findings demonstrate that PLE provides direct experimental access to the previously unexplored high-energy IX states in van der Waals
heterostructures.
Read the full abstract ▾
All authors Chirag Chandrakant Palekar, Paulo E. Faria Junior, Tobias Manthei, Maximilian Nagel, Bhabani Sankar Sahoo, Shachi Machchhar, Imad Limame, Martin Podhorský, Jaroslav Fabian, Bárbara Rosa, Stephan Reitzenstein
Quantum Physics
Convergence monitoring of quantum Gibbs samplers
Nikolaos Louloudis, Ruben Ibarrondo, Mikel Sanz et al. (+1 more)
Recent progress in fully
quantum Markov chain Monte Carlo methods enables efficient Gibbs-state sampling on
quantum computers [Chen et al., Nature 646, 561 (2025)]. Although rigorous worst-case bounds on mixing times remain largely inaccessible for classically intractable systems, experience from classical Monte Carlo suggests that convergence of relevant observables may nevertheless be rapid. This raises the practical question of how to diagnose convergence efficiently, i.e., with at most
polynomial overhead. We propose a low-cost criterion for convergence monitoring that exploits the weak measurements inherent in
quantum Gibbs samplers and their
qubit-efficient variants [Ding et al., arXiv:2508.05703 (2025)]. Our approach is based on the observation that, at thermal
equilibrium, the net energy flow between system and environment vanishes and energy-exchange statistics satisfy a balance condition. This condition appears in the distribution of (quasi-)frequencies extracted from the weak-measurement record and we use it to construct a
Hamiltonian-agnostic stopping criterion based solely on data already generated by the sampler. We provide a statistical analysis, along with numerical and analytical studies to understand its performance, assumptions, and limitations.
Read the full abstract ▾
All authors Nikolaos Louloudis, Ruben Ibarrondo, Mikel Sanz, Mario Berta
Optics
A Heterogeneous 200 mm Silicon Nitride Photonics Platform for Visible-to-Near-Infrared Applications via Micro-Transfer Printing
Konstantinos Akritidis, Gaudhaman Jeevanandam, Manuel Reza et al. (+11 more)
The commercialization of next-generation technologies, including optical interconnects,
quantum computing, AR/VR, and medical diagnostics, requires a low-loss photonic platform offering compact, multifunctional systems in the visible and near-infrared range. Although silicon nitride (SiN) is an excellent material due to its ultra-low loss and broad transparency window, integrating active components such as light sources, modulators and photodetectors from diverse material platforms in a scalable, reliable way remains challenging. Micro-transfer printing is an emerging wafer-scale heterogeneous integration technology that can be implemented as a back-end post-processing step without disrupting the primary in-line fabrication process. In this work, we present a dual LPCVD SiN layer platform fabricated in a 200 mm CMOS pilot line, that incorporates micro-transfer printing modules, allowing the integration of active components on well defined recesses. A hydrogenated amorphous silicon layer is also available to increase the versatility of the platform allowing for evanescently-coupled III-V
lasers as well as other passive functionality in the near-infrared region. We report full wafer-scale measurements showing low optical SiN losses of 4 dB/cm and 0.23 dB/cm at a wavelength of 488 nm and 940 nm respectively. In addition, a transition loss of only 0.35 dB is obtained from the SiN to the a-Si:H layer, in good agreement with simulated values. Finally, to showcase more advanced functionality, GaAs-based gain sections are micro-transfer printed on several dies, achieving consistent die-to-die lasing at 970 nm with on-chip optical powers of approximately 1 mW. These results showcase the potential of the integrated photonics platform towards unlocking a wide range of new applications in the sub-1-$\mu$m spectral region.
Read the full abstract ▾
All authors Konstantinos Akritidis, Gaudhaman Jeevanandam, Manuel Reza, Maximilien Billet, Jeonghwan Song, Sandeep Seema Saseendran, Vittal Prakasam, Jan-Philipp Koester, Jörg Fricke, Günther Roelkens, Markus Weyers, Roelof Jansen, Pol Van Dorpe, Bart Kuyken
Quantum Physics
Zero-G: A Pre-Decoder-Aware Decoder for Quantum Error Correction
Peter Wegmann, Theofilos Augoustis, Aleksandra Świerkowska et al. (+2 more)
Fault-tolerant
quantum computing requires classical decoders that keep pace with the underlying hardware, translating syndrome measurements into corrections fast enough to avoid an exponential backlog. To meet this real-time constraint, pre-decoders have emerged as part of a hierarchical decoding approach to resolve simple, local errors before passing a sparser residual syndrome to a strong decoder. While pre-decoding should, in theory, speed up the strong decoder, in practice, the speedup is only marginal, since existing strong decoders are designed to decode dense syndromes and cannot exploit the sparsity provided by pre-decoders. To address this, we present Zero-G, a strong decoder designed for use alongside pre-decoders. As a
stochastic approximate minimum-weight perfect matching (MWPM) decoder, Zero-G exploits sparse residual syndromes, dynamically trading latency for accuracy rather than relying on an all-or-nothing runtime-accuracy trade-off. By decoupling hardware control from the decoding core itself, we enable heterogeneous deployment across both FPGAs and CPUs without maintaining separate implementations. Zero-G achieves a $10\times$ latency improvement over existing strong decoders at matching accuracy, with worst-case sub-350ns decoding at code distances up to d=15, while scaling to 640 logical
qubits on a single 128-core CPU and 32 logical
qubits on a single AMD Versal V80 FPGA.
Read the full abstract ▾
All authors Peter Wegmann, Theofilos Augoustis, Aleksandra Świerkowska, Emmanouil Giortamis, Pramod Bhatotia
Mesoscale and Nanoscale Physics
Emission dynamics in zincblende InAsxP1-x quantum dots in InP nanowires: influence of quantum dot size, composition and nanowire geometry
Tomasz Gzyl, Giada Bucci, Krzysztof Gawarecki et al. (+10 more)
Hereby, we present an experimental and theoretical investigation of emission dynamics in zincblende InAsxP1-x
quantum dots (QDs) embedded in InP nanowires (NWs) grown via vapour-
liquid-solid mechanism by chemical beam epitaxy, using Au nanoparticles as a nucleation catalyst. By measuring time-resolved photoluminescence from an ensemble of QD-NWs it was possible to determine the
exciton lifetime dependence on QD composition and height. Changes in the InP shell thickness surrounding the InP NW stem with a QD, brought additional insight into the influence of photonic environment on the carrier dynamics. High-resolution transmission electron microscopy, combined with energy-dispersive X-ray spectroscopy, provided actual structural parameters. The experimentally obtained lifetimes were interpreted in the light of results of 8 band kp calculations combined with configuration-interaction model to take into account the Coulomb interactions and finite-difference time domain photonic simulations to include the effect of optical confinement. The full understanding of the experimental results required considering both, the changes in the QD potential and the Purcell effect, the latter leading to spontaneous emission inhibition in the case of NWs with thin InP shell.
Read the full abstract ▾
All authors Tomasz Gzyl, Giada Bucci, Krzysztof Gawarecki, Elisa García-Tabarés, Anna Musiał, Valentina Zannier, Ylea Vlamidis, Fabio Beltram, Julian V. Montero, Beatriz Galiana, Lucia Sorba, Wojciech Rudno-Rudziński, Grzegorz Sęk
Mathematical Physics
A Hamiltonian approach to the CH-KP equation
R. Camassa, G. Falqui and E. Sforza
A model governing quasi-unidirectional wave propagation at the surface of a shallow layer of water is derived from Euler equations by long wave asymptotics together with
Hamiltonian reduction techniques. The balance between nonlinearity, dispersion and weak dependence on the second planar coordinate is examined and results in the so-called CH-KP equation, a mildly nonlinear version of the well known Kadomtsev-Petviashvili equation. The
Hamiltonian structure of the model is obtained by Dirac reduction from the intermediate step of a fully-nonlinear, long-wave system for stratified fluids. A particular scaling is considered that reduces such system to the one-dimensional CH equation in a limiting case. Examples of weak peakon-type solutions are provided, chosen to illustrate the collision behavior supported by the limiting equation.
Read the full abstract ▾
High Energy Astrophysical Phenomena
The progenitors and circumstellar environments of stripped-envelope interacting supernovae from BPASS
B. Warwick, J. Lyman, D. L. Coppejans et al. (+4 more)
Understanding the progenitors of stripped-envelope interacting
supernovae (SEISNe) is crucial for probing the final stages of massive
star evolution. Despite this, their rarity means the nature of their progenitors remains poorly constrained. We investigate the progenitors of SEISNe, using the Binary Population and Spectral Synthesis
stellar evolution models. The 30,153
stellar models that result in hydrogen-poor core-collapse
supernovae (SN) includes both binary and single
stars, spanning 13
metallicities ($Z=10^{-5}$ to $0.04$). Circumstellar material (CSM) formation during their last 100\,kyr is reconstructed from line-driven and Roche lobe overflow (RLOF) mass loss using three scenarios for the CSM, one looking at a wind only distribution for the CSM, and two involving the formation of a circum-binary disc (CBD). Light curve parameters from each scenario are calculated using an analytical model and fiducial SN explosion parameters. We find only the two CBD scenarios, and consequently no single
star models, reproduce the luminosities and rise times of observed SEISNe. The inferred rates are comparable to observations. Expected progenitors were only found in models with ZAMS masses of $14-40\,$M$_{\odot}$ at $\geq Z_\odot$ and $30-40\,$M$_{\odot}$ at $< Z_\odot$. Modelling the
radio emissions shows that early ($\leq8\,$days) and high frequency ($\geq70\,$GHz) observations are required to constrain the nature of CBDs in these systems. These results indicate that, without phenomena such as eruptive mass loss, SEISNe require massive
stars in binary systems in order to produce sufficient masses of CSM and confine them close to the progenitor.
Read the full abstract ▾
All authors B. Warwick, J. Lyman, D. L. Coppejans, C. M. Byrne, J. J. Eldridge, M. Pursiainen, E. R. Stanway
Fluid Dynamics
Coherent structure modulation and recovery in drag-reduced turbulent boundary layers
Traian Bistriceanu, Vyacheslav A. Kovalyov, Pradyumn Mishra et al. (+3 more)
Drag reduction is achieved by a steady square-wave forcing of the spanwise wall velocity, based on the experiments in Knoop et al. (Phys. Rev. Fluids, 10, 2025). Particle tracking velocimetry data are analyzed for a non-actuated reference case and actuation at forcing amplitude $A^+ = 12$ ($+$ denotes viscous scaling) for three streamwise forcing wavelengths, which correspond to sub-optimal ($\Lambda_x^+ = 471$), near-optimal ($\Lambda_x^+ = 942$), and post-optimal ($\Lambda_x^+ = 1884$) drag reduction conditions. Conditionally averaged fields on large-scale bursts of turbulent kinetic energy show that forcing suppresses near-wall ejections across all cases, while outer-layer sweep suppression strengthens with $\Lambda_x^+$. Post-optimal forcing exhibits streamwise-periodic attenuation and recovery of
turbulence. The recovery phenomenon is caused by an enhancement of very small scales, significantly smaller than those typically energetic in wall
turbulence, and is linked to the emergence of small-scale bursting events. While these small-scale bursts are statistically insignificant in the non-actuated and sub-optimal cases, their frequency increases by a factor of four between the near-optimal and post-optimal cases. The small-scale bursts exhibit uniform signatures and intensities, hinting at the possible universality of the recovery phenomenon. A wavelet analysis shows that, in the post-optimal case, very small scales increase progressively in the streamwise direction in regions where the wall velocity remains constant, driving a cyclic pattern of small-scale re-energization and suppression consistent with earlier statistical analysis. This
turbulence modulation mechanism is scale-selective: while small-scale structures emerge periodically, large-scale motions are more effectively suppressed as the forcing wavelength increases.
Read the full abstract ▾
All authors Traian Bistriceanu, Vyacheslav A. Kovalyov, Pradyumn Mishra, Roann A. A. Kerbergen, Max W. Knoop, Bas W. van Oudheusden
Instrumentation and Detectors
Performance and prospects of polyurethane-based scintillators for neutron and gamma radiation detection
Olga Maiatska, Torsten Duennebacke, Roland Hillebrands et al. (+6 more)
Organic scintillators have been used for decades to detect gamma rays or fast
neutrons at low cost. Despite extensive efforts it is still difficult to combine stability, ruggedness, high light yield, and decent pulse-shape discrimination (PSD) in a single scintillator material. We took the unusual approach of
embedding phosphors and wavelengths shifters in a solid polyurethane
matrix, trying to combine the robustness of a common construction material with scintillating properties and PSD performance. The plastic scintillators resulting from years of research ultimately meet these intentions. Moreover, the production process is less demanding and less complex than that of conventional plastic scintillators. It allows to directly integrate light sensors or electronics into the scintillator. This opens the door for the construction of extremely compact and robust plastic detectors for the simultaneous detection of fast
neutrons and gamma rays. This paper presents basic recipes and properties of scintillators based on this novel conception and discusses first applications in
neutron imaging and personal radiation protection.
Read the full abstract ▾
All authors Olga Maiatska, Torsten Duennebacke, Roland Hillebrands, Achim Kreuels, Martin Kreuels, Guntram Pausch, Falko Scherwinski, Andreas Wolf, Juergen Stein
Materials Science
Exciton-induced magnons carrying orbital angular momentum in CrI3
Martin Pavelka, Vishal Shokeen, Ruslan Chulkov et al. (+15 more)
Magnons are collective
spin excitations that contain and transport
spin angular momentum in
magnetic materials. It has been suggested that they can also carry orbital angular momentum in analogy to the electronic motion around the
nucleus. We explore the real-space
topology of
magnon wave-packets emanating from atomic-like
excitons in the
ferromagnetic insulator CrI3 and demonstrate the existence of orbital angular momentum in such wave-packets. We reveal that orbital angular momentum of
magnons is nearly equal to their
spin angular momentum and compensates the latter. This illustrates the existence of an unexplored internal angular momentum balance and demonstrates that the magnetization can be quenched without the need of angular momentum exchange with the
lattice.
Read the full abstract ▾
All authors Martin Pavelka, Vishal Shokeen, Ruslan Chulkov, Soma Dutta, David Muradas Belinchón, Ulrich Noumbe, Mahmoud Abdel-Hafiez, M. Venkata Kamalakar, Mathias Augustin, Vitaliy Goryashko, Torstein Hegstad, Johan H. Mentink, Jamal Berakdar, Oscar Grånäs, Anders Bergman, Olle Eriksson, Anna Delin, Hermann A. Durr
Mesoscale and Nanoscale Physics
Extracting higher-order nonlinearities in nanomechanical resonators using the backbone relation
Maria Kallergi, Daniel K. J. Boneß, Maximilian Seitner et al. (+2 more)
Nanomechanical resonators are a powerful platform for studying nonlinear dynamics with high sensitivity and precision. We explore the nonlinear response of a high-Q nanomechanical string resonator in and beyond the Duffing regime and introduce a robust framework for accurately extracting its conservative nonlinearities. The method is based on the backbone curve obtained from ringdown measurements, making it inherently resilient to small frequency fluctuations while explicitly accounting for both
symmetry-breaking and non-
symmetry-breaking nonlinearities. To validate the approach, we perform complementary ringdown and frequency-response measurements on the nanostring resonator and
benchmark the backbone-based extraction against established frequency-response techniques. The comparison confirms the accuracy of the proposed framework and demonstrates its advantages over conventional methods for nonlinear characterization.
Read the full abstract ▾
All authors Maria Kallergi, Daniel K. J. Boneß, Maximilian Seitner, Wolfgang Belzig, Eva M. Weig
Quantum Gases
Benchmarking the fermionic quasi-1D many-body problem
Ekaterina Gradova and Frédéric Chevy
We investigate the validity of effective one-dimensional models for quasi-1D fermionic systems by benchmarking a coupled-channel approach against the exact low-energy theory derived from the underlying three-dimensional problem in the weakly and strongly attractive limits. We show that reproducing the exact two-body scattering amplitude is insufficient to construct the correct effective low-energy theory of quasi-1D
fermions. In the weakly attractive regime, it does not capture the emergent three-body interaction induced by transverse excitations. In the strongly attractive regime, it yields an atom-dimer scattering length with an incorrect dependence on the three-dimensional scattering length. These results demonstrate the limitations of effective one-dimensional descriptions based solely on two-body physics and highlight the need to explicitly include few-body correlations in quasi-1D systems.
Read the full abstract ▾
Fluid Dynamics
Measurements of non-linear energy transfer in canonical and drag-reduced turbulent boundary layers
Max W. Knoop, Bas W. van Oudheusden and Rahul Deshpande
Three-dimensional particle-tracking velocimetry (3D-PTV) measurements were used to compute the spectral transport of the Reynolds-stress tensor. The experimental framework is validated for a zero-pressure-gradient (ZPG) turbulent boundary layer (TBL) at a friction Reynolds number $Re_\tau = 1020$, demonstrating that the dominant non-linear energy transfer mechanisms are adequately resolved to draw flow physics-based conclusions. For the streamwise Reynolds stress in the ZPG TBL, a component-wise decomposition of the non-linear transport term is considered for the first time, which reveals distinct energy transfer mechanisms associated with the spanwise and wall-normal advection. The same experimental framework was applied to a drag-reduced ($\approx 38\%$) TBL flow, achieved by imposing a steady streamwise-alternating spanwise wall velocity. This wall forcing causes a strong attenuation of non-linear energy transfer and its shift away from the wall. The energy transfer mechanisms remain qualitatively similar to those of the canonical ZPG TBL, suggesting that the existing mechanisms simply readjust to their new low-turbulent-energy state.
Read the full abstract ▾
Mathematical Physics
Geometric theory of generalised continua using moving frames
Boris Kolev and Clément Ecker
Generalised continuum theories couple the macroscopic deformation and the micro-/meso-scopic deformation of an underlying micro-structure. They can account for internal length-scale effects and higher-order mechanical loadings absent from classical Cauchy elasticity and has shown its efficiency in modelling metamaterials. This has led to a proliferation of higher-grade and higher-order models (e.g. strain-gradient, micromorphic, micro-polar) whose underlying kinematic reduction strategies, in particular to reduce the number of material parameters, are rarely identifiable from the free energy alone. It leaves two open issues: the lack of a systematic criterion for selecting an appropriate model, and a persistent ambiguity regarding the physical status of the local frames (”directors of matter”) used in their kinematic description. Are they physical quantities describing the change of state of the given micro-structure or arbitrary kinematic descriptors of its deformation\,? This work addresses both questions through a gauge-theoretic formulation of generalised continua in finite strains. While relying on tools and modelling choices consistent with the existing
geometric literature on continuum mechanics, the present approach departs from it in its objectives, aiming at a unifying classification of available mechanical models rather than the description of a specific microstructural phenomenon such as defects. In this work, generalised configurations are defined as moving frames over classical configurations, and invariance with respect to the reference generalised configuration is shown to be a necessary and sufficient condition for a gauge invariance, recovering the micromorphic theory as the general-purpose theory of the deformation of arbitrary directors of matter. A systematic classification of first-order generalised media follows from structural group reduction, while strain-gradient continua are recovered through convected frames, and finally constrained media (e.g. couple-stress) are addressed.
Read the full abstract ▾
High Energy Astrophysical Phenomena
Searching for core-collapse supernovae in binaries with ZTF
Sylvia J. Zhu, Jakob Nordin, Emma de Oña-Wilhelmi et al. (+1 more)
Context. Stripped envelope
supernovae occur in massive
stars that have lost their outer layers before exploding, possibly from binary interactions. Recently, SN 2022jli was detected with significant periodic oscillations in its lightcurve, likely due to
accretion from a binary companion onto the newborn compact object. Aims. While evidence for periodic oscillations has been found in a few bright and noteworthy
supernovae, the population properties are best understood with systematic searches of large data sets. We present prospects for running a search on data from ZTF and similar surveys that is flexible and computationally inexpensive, with the goal of setting up a search in realtime on data from ZTF, LSST, and similar surveys. Methods. We simulate core collapse
supernova lightcurves with additional features from the binary interactions. We use spline fits to remove the underlying
supernova behavior and isolate the periodicities, then apply a Lomb-Scargle periodogram to recover the simulated period. By varying the conditions, we can make recommendations for different kinds of data sets. Finally, we run the search on two sets of archival ZTF
supernovae to illustrate the concept. Results. For a wide range of binary interaction parameters, we find that a long baseline (200 days) of observations with a three-day cadence effectively retrieve ~50% of the binary oscillations. However, this rate plummets with more typical observation durations; only a few percent are recoverable with a 30-day observation, and 10% with a 75-day observation. A substantial fraction of
supernovae could therefore have binary companion interactions that have simply been undetected. Out of 212 moderately bright and well observed ZTF
supernovae, we find suggestions of periodic oscillations in two candidates.
Read the full abstract ▾
All authors Sylvia J. Zhu, Jakob Nordin, Emma de Oña-Wilhelmi, Andrea Ercolino
Solar and Stellar Astrophysics
A new methodology for inferring the plasma conditions in solar flare energetic electron source regions from in situ electron energy spectra
Samuel Carter, Natasha L. S. Jeffrey, Robert T. Wicks et al. (+1 more)
The conditions within
solar flares that lead to efficient electron acceleration are not well constrained. It is not clear whether the populations accelerated out into the heliosphere and inward into the chromosphere originate in the same regions. By analysing the energy distributions of heliospheric populations, modelling suggests that it should be possible to see evidence of their originating region(s), including the presence of hot, dense
flare plasma. By creating and utilising a novel in situ spectral analysis package called INSPEX we have performed this analysis for
flare electrons observed in situ on 09/10/2021, constructing both peak flux and fluence spectra from combined
Solar Orbiter in situ electron measurements. We compare how differing methodologies for combining the
datasets influence the spectral shapes and the retrieved parameters over an energy range of 0.5-80 keV. We fit different functions to the multi-component form of the energy spectra, testing combinations of thermal and/or power law components, comparing the fit statistics. We find that the spectra can be fitted with two distinct thermal curves at energies below 20 keV, corresponding to typical corona/active region and flaring material temperatures, varying between 1.4 - 4.1 MK and 12.5 - 23.1 MK depending on the rebinning window and peak flux extraction method. This study showcases how INSPEX can provide a novel and user-friendly methodology for studying electron spectra with different instrumentation, allowing investigation of multiple spectral types and signatures of acceleration and transport. This first application provides a
benchmark case for the analysis of similar
flares.
Read the full abstract ▾
All authors Samuel Carter, Natasha L. S. Jeffrey, Robert T. Wicks, Georgios Nicolaou
Superconductivity
Spin Josephson diode effect induced by higher-harmonic spin Josephson currents in a diffusive Josephson junction
Shin-ichi Hikino
We theoretically investigate the
spin Josephson diode effect (SJDE) in a diffusive Josephson junction with a Rashba metal layer under a
ferromagnetic exchange field. Within the quasiclassical Green's function framework, we derive analytical expressions for the first- and second-harmonic
spin Josephson currents. The interplay between Rashba
spin-orbit interaction and the exchange field breaks inversion and time-reversal
symmetries, generating additional cosine terms in the
spin current-phase relations and a finite phi0 phase shift. This phase shift induces an intrinsic asymmetry between forward and backward
spin currents, leading to the SJDE without an external
magnetic field. Numerical results show that the efficiency decreases with increasing metal thickness due to suppression of the second-harmonic component, while its dependence on
spin-orbit interaction strength reflects competing effects between phase shift enhancement and harmonic suppression. These findings demonstrate that the interplay between harmonic components provides a mechanism for nonreciprocal
spin transport without requiring suppression of
spin-singlet correlations.
Read the full abstract ▾
High Energy Physics (Theory)
Coarse-Graining and Long-Range Response in Generated Systems
Jinku Guo
We study when a reduced description preserves the response to an applied source. For systems defined by continuously differentiable state updates and observations a bounded surjective linear coarse map gives differentiable descent when the projected maps are constant on each fibre. Their common source response is then preserved on the invertible domain. For approximate descent an exact error identity separates defects in the update and source coupling from defects in the readout and direct term. Resolvent and contour estimates carry these errors and the displacement of the reference branch to visible poles and their residues at shifted critical roots. In a reciprocal
Hilbert-space realisation an isolated finite-dimensional critical subspace with a positive crossing
matrix has a positive-semidefinite finite-rank residue when the endpoint operator is self-adjoint and the complementary inverse is bounded. Source overlap determines its visible directions. Arithmetic and reflecting-heat examples separate stationary response preservation from memoryless dynamical closure. In the two-mode example pole displacement decays geometrically with the retained
memory length. The residue error includes an additional factor of that length. For a matched
vacuum covariance the residue is the zero-mass atom of its positive spectral measure. This identification uses the same physical projection and source pairing together with the continuation and subtraction conventions and endpoint matching.
Read the full abstract ▾
Nuclear Theory
Diffusion and shear viscosity coefficients of hot isospin asymmetric strange hadronic matter using a chiral SU(3) model
Amruta Mishra, Shujun Zhao and Tetsufumi Hirano
We study the
diffusion and shear viscosity coefficients of hot isospin asymmetric strange hadronic matter. The effects due to the
baryon density, isospin, strangeness, and temperature on the nucleons and hyperons are studied within a
chiral SU(3) model. The medium modifications of the
baryons arise due to interactions with the mean scalar and vector fields within the model. The thermodynamic and transport properties are studied in the hot strange hadronic matter. The
diffusion matrix associated with the multiple charges (
baryon number, isospin, and strangeness), as well as the coefficient of shear viscosity, are computed from the Boltzmann equation using first-order Chapman–Enskog expansion within the relaxation time approximation. The
diffusion coefficient, $\kappa_{QQ}$ corresponding to the conserved electric charge has also been studied in the present work. There are observed to be significant effects from the isospin asymmetry as well as the strangeness of the medium on the
diffusion coefficients. The coefficient of shear viscosity, $\eta$ is observed to have a large enhancement in the presence of finite strangeness in the medium due to additional contributions from the hyperons. The effects due to isospin asymmetry on the shear viscosity coefficient is however observed to be marginal both in
nuclear and hyperonic matter. The present study can be relevant for the experimental observables of asymmetric relativistic heavy-ion collisions, e.g., in the compressed baryonic matter (CBM) experiment at the FAIR facility at GSI as well as in the future J-PARC-HI program.
Read the full abstract ▾
Materials Science
Resonantly-enhanced Raman response in graphene-capped bismuthene on SiC
Lukas Gehrig, Cedric Schmitt, Erica Fragomeni et al. (+15 more)
Two-dimensional
quantum spin Hall insulators based on atomic monolayers offer a promising route toward dissipationless electronics, yet their practical use is often limited by environmental instability. Encapsulating the system with a
graphene capping layer has been shown to be a reliable method to prevent oxidation and degradation. However, the confirmation of a successful encapsulation still relies on ultra-high
vacuum techniques, that considerably slow the process. Here, we present an ex situ, rapid, nondestructive and spatially resolved Raman characterization of
graphene-capped bismuthene, a honeycomb monolayer of Bi on SiC. A pronounced Raman scattering peak at around 122 cm-1 is identified as the E2g
phonon of bismuthene, via a comparison with density functional perturbation theory calculations. We use excitation-energy and polarization-dependent Raman measurements to enable an unambiguous assignment of the spectral features. Tuning the excitation energy close to the excitonic transition in pristine bismuthene, we observe a strong enhancement of the Raman response and the emergence of additional scattering peaks. In this regime, higher-order
phonon features, as well as interfacial modes between bismuthene and the SiC substrate, become visible, suggesting the involvement of resonant scattering processes. Our results establish Raman micro-spectroscopy as a versatile tool for probing
graphene-protected
quantum materials, providing access to
lattice dynamics and interlayer coupling.
Read the full abstract ▾
All authors Lukas Gehrig, Cedric Schmitt, Erica Fragomeni, Simone Sotgiu, Stefan Enzner, Tommaso Venanzi, Bing Liu, Kilian Strauß, Jonas Erhardt, Martin Kamp, Elena Stellino, Paolo Postorino, Jörg Schäfer, Simon Moser, Christoph Stampfer, Giorgio Sangiovanni, Ralph Claessen, Leonetta Baldassarre
Solar and Stellar Astrophysics
A multi-epoch spectral and photometric study to understand the nature of the interesting Be star candidate HD 249179
Suman Bhattacharyya, Blesson Mathew, S Muneer et al. (+2 more)
HD 249179, a B5
star with unclear classification as either a classical Be
star or a high-mass X-ray binary (HMXB) system, is investigated using the first multi-epoch spectral and photometric analysis over 5.5 years (2017-2023). Optical spectroscopy from LAMOST, BeSS, and the Himalayan Chandra
Telescope show large H-alpha variability (-17.6 to -3.2 angstrom, in six days, returning to -31.3 angstrom, in 2022) and the presence of Paschen and O I lines, confirming active circumstellar disc dynamics. H-alpha double peak profiles show weak V/R ratio variations 0.92–1.28 indicating one-armed density waves. TESS observations presents hybrid beta Cephei/slowly pulsating B-type variability with primary frequencies of 3.5 c/d and 1.5-1.6 c/d, and an outburst-like brightening with phase-dependent frequency
evolution. Simultaneous anti-correlation between optical brightness and H$\alpha$ equivalent width suggest moderate disc inclination.
Gaia DR3 CMD analysis rules out HD 249179 as a BeXRB but instead places it in the classical Be-
star region. The BeppoSAX survey, despite previous X-ray cataloging, found no emission above the sensitivity limits. Our analysis shows that HD 249179 is most likely a classical Be
star with variable circumstellar disc activity and hybrid pulsations, and that there is no strong evidence for an HMXB classification.
Read the full abstract ▾
All authors Suman Bhattacharyya, Blesson Mathew, S Muneer, Sreeja S Kartha, Prakruthi Prasad
Nuclear Theory
Theoretical Review of Critical Point Predictions
Maneesha Sushama Pradeep
This review summarizes recent theoretical progress on the QCD equation of state near the critical point and developments in the maximum
entropy freeze-out framework, which provides a systematic connection between hydrodynamic fluctuations and hadronic multiplicity cumulants. We also discuss recent applications of this framework, together with advances in the dynamical
evolution of critical fluctuations.
Read the full abstract ▾
Physics and Society
Vulnerability Modeling for the Adaptation of Physical Systems to Climate Change Extremes
Matthieu Dutel
Climate change is modifying the frequency and intensity of extreme hazards in a non-uniform spatial manner, increasing the risk of damage for existing physical systems. Vulnerability modeling based on vulnerability curves provides a quantitative link between hazard intensity and physical damage, supporting adaptation strategies. This paper proposes conceptual frameworks for vulnerability models of physical systems in the context of
climate change, aimed at supporting vulnerability based adaptation. A theoretical use case illustrates the methodology: potential damage on power transmission towers facing wind gust hazards across France, modeled through vulnerability curves. Despite strong assumptions, this theoretical case study demonstrates how vulnerability models can guide adaptation by reducing intrinsic vulnerability, adapting the physical system to maintain acceptable damage levels under evolving
climate extremes.
Read the full abstract ▾
High Energy Physics (Experiment)
Long-Delayed Afterpulse Measurement of JUNO 20-inch Photomultiplier Tubes
Xiaojie Luo, Cailian Jiang, Haojie Dong et al. (+9 more)
In large-scale
liquid scintillator detectors such as the Jiangmen Underground
Neutrino Observatory (JUNO), high-intensity events like
cosmic muons induce photomultiplier tube (PMT) afterpulses that can interfere with the analysis of delayed physics signals. To systematically evaluate this instrumental background, we present a dedicated measurement of long-delayed afterpulses in two types of JUNO 20-inch PMTs: a dynode-based PMT and a microchannel-plate (MCP) PMT. The afterpulse time profiles were first characterized within a direct 1.8~ms waveform window and were further extended to 20~ms using a sliding-window readout strategy. Distinct long-delayed components are observed, revealing a strong dependence on the PMT multiplication structure. The dynode PMT exhibits a broad afterpulse component peaking at approximately 260~$\mu$s, whereas the MCP-PMT shows a pronounced peak around 90~$\mu$s, an additional component around 550~$\mu$s, and a much smaller, broadly distributed millisecond-scale component. For the microsecond-scale components, the afterpulse yield per primary photoelectron is at the $10^{-3}$ level in the selected delayed windows and increases approximately linearly with the primary light intensity. The accumulated delayed activity can therefore become non-negligible following high-intensity events. These quantitative findings provide critical inputs for PMT response characterization and for the accurate modeling of delayed correlated backgrounds in high-precision
neutrino experiments.
Read the full abstract ▾
All authors Xiaojie Luo, Cailian Jiang, Haojie Dong, Yuduo Guan, Gaosong Li, Zhonghua Qin, Zhenning Qu, Junyu Shao, Mingxia Sun, Liangjian Wen, Zeyuan Yu, Boyi Zheng