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Physics

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Thursday 11 June

Quantum Physics

Interference of critical dynamics associated with zero modes

Zhi-Han Zhang, Han-Chuan Kou and Peng Li

We study the interference of critical dynamics associated with zero modes (ICDZM) in the generalized Creutz ladders using closed quench paths that pass through two critical points successively. By reading out the final zero-mode transfer probability, we find rich ICDZM interference patterns dependent on the quench path. In particular, when the closed path links two topologically nontrivial phases, the ICDZM pattern may either vanish or exhibit period doubling. Within the framework of WKB analysis, this phenomenon is well clarified by the interference phase accumulated in the quench procedure. We also demonstrate that the zero-mode transfer probability can be detected by the deviation of the boundary particle number from its initial fractional value, which arises from the blending of bulk modes in the critical dynamics. As an edge defect, the zero-mode transfer probability captures both the ICDZM oscillation and the known anomalous defect production in a non-closed quench path. These results identify ICDZM and the corresponding edge defect as probes for critical dynamics associated with topological zero modes.
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Optics

Robustness against disorder in topological fibre lasers with explicitly broken PT symmetry

Brook Salter, Nathan Roberts, Habib Rostami et al. (+2 more)

Fibre lasers realise a large gain medium in a compactly coiled fibre. Disorder due to fabrication can negatively impact the stability of their lasing modes, especially in multi-core fibres. Recently, topological fibres (without gain) have been experimentally demonstrated to be robust against fabrication disorder, but topological fibre lasers have not yet been designed or modelled. Here, we use a combination of mode-coupling theory and finite-element simulations to design and model a topological laser based on a non-Hermitian Su-Schrieffer-Heeger (SSH) chain embedded in a photonic crystal fibre. Our design is based on a winding-number invariant in combination with a PT-symmetric SSH bulk. We show that the topological boundary mode is selectively amplified when extra gain is added at the topological interface. Even with nonlinearity added through saturable gain, the lasing supermode retains its robustness against disorder. We present a realistic design for a topologically robust fibre laser using readily available stack-and-draw methods with doped cores. This work establishes a new approach for imbuing non-Hermitian photonic systems with topological protection, with technological implications towards generating robust quantum and classical signals.
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All authors Brook Salter, Nathan Roberts, Habib Rostami, Peter J. Mosley, Anton Souslov

Plasma Physics

Ultrashort Two-Pulse Train Generation on a 100 TW Laser Beamline Using a Delay Mask After the Final Focusing Optics

David Gregocki, Luca Labate, Federica Baffigi et al. (+2 more)

Experimental results showing the generation of an ultrashort two-pulse train using a two-section delay mask placed downstream of the off-axis parabola focusing optics are reported. Based on the initial simulation results, a circular fused silica plate with a central aperture and a measured thickness of $570\pm50$ $\mu$m used in the quantitative delay calculation was designed to enable two distinct transverse portions of the incident laser pulse to be focused, ideally, with equal intensity. This fulfills one of the requirements of the resonant multi-pulse ionization injection (ReMPI) scheme for laser wakefield acceleration. As an intermediary step, a calibration of Gafchromic EBT4 films against laser fluence was established, enabling direct characterization of the unattenuated transverse beam profile. The experiment was carried out at the CNR-INO Intense Laser Irradiation Laboratory (ILIL) using a 240 TW laser system operated at 100 TW as part of the ongoing preparation for the first experimental demonstration of ReMPI. The pulse-to-pulse delay introduced by the delay mask was experimentally measured (at a reduced power, as customary for temporal autocorrelation measurements) to be $\simeq 901$ fs, in good agreement with the expected value of $\simeq 888$ fs. While the pulse-to-pulse delay is not yet optimized for ReMPI operation at practically relevant plasma densities, the experimental results demonstrate the feasibility of the proposed delay-mask concept.
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All authors David Gregocki, Luca Labate, Federica Baffigi, Lorenzo Fulgentini, Leonida Antonio Gizzi

Other Condensed Matter

Transformation of the gyrotropic mode spectrum of the FM / AFM disk via vortex imprinting

E. V. Skorokhodov, E. A. Karashtin, I. A. Fedotov et al. (+2 more)

We experimentally investigate the magnetic gyrotropic mode in a system of vortex ferromagnetic (FM) nanooscillator exchange coupled to an antiferromagnetic (AFM) layer. The micron-sized disks formed from the $Ni_{80}Fe_{20}$ (12 nm) / $Ir_{80}Mn_{20}$ (5 nm) FM/AFM heterostructure are prepared so that the vortex magnetic state is imprinted into the AFM layer. We apply a magnetic resonance force microscopy (MRFM) method to locally study magnetic oscillations in single FM/AFM disks. We show that the gyrotropic mode frequency is significantly (approximately four times) shifted to the high frequency range compared to a similar structure consisting of a single ferromagnetic disk. Upon applying an in-plane magnetic field, we observe a strong peak at a double frequency which was previously predicted in theory. This shows that nonlinearity in vortex dynamics is strongly enhanced in the FM/AFM system under investigation. Thus the magnetic imprinting technology reveals great potential for future application in high-frequency spintronic devices.
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All authors E. V. Skorokhodov, E. A. Karashtin, I. A. Fedotov, I. Yu. Pashen'kin, M. V. Sapozhnikov

General Relativity and Quantum Cosmology

Thermodynamics of polymerized vacuum regular black holes in anti-de Sitter spacetime

Sepideh Bakhoda and Ioannis Soranidis

We derive a class of vacuum regular black holes inspired by effective loop quantum gravity dynamics and extend the construction to asymptotically anti-de Sitter spacetimes. The derivation is based on a deparameterized Lemaitre–Tolman–Bondi formulation, where an auxiliary dust field is introduced only to define an internal time and does not act as a matter source. In spherical symmetry, the dynamics reduces to a set of independent radial shells, giving rise to a factorized shell Hamiltonian and to a Birkhoff-type property: for a fixed reconstruction function and cosmological constant, the static geometry is uniquely determined by the mass. Within this framework, we establish the conditions for curvature regularity at the center and construct several regular black hole models with de Sitter cores and corresponding models with anti-de Sitter cores. We then study their thermodynamics in the extended phase space, using the Hawking–Page transition to compare the de Sitter- and anti-de Sitter-core branches and show that their quantitative differences arise from the deformation of the physical outer-horizon branch rather than from regularity alone.
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Optics

Can non-orthogonal bases form stable skyrmionic beams?

Zan Zhang, Zhujun Ye, Zhenyu Guo et al. (+7 more)

Skyrmions, topologically stable spin textures, have recently garnered significant attention in optics promising robust high-density information transition and nontrivial light-matter interaction. It was believed that the optical skyrmionic beams should be constructed by superposition of two orthogonal spatial modes with orthogonal polarizations to obtain topologically stable propagation. Here, we surprisingly find that propagation-stable skyrmionic beams can still be formed by superpositions of neither orthogonal spatial modes nor orthogonal polarizations. We theoretically present the mechanism to control the stable skyrmionics beams through the hybrid superposition of modes from the Hermite-Gaussian and Laguerre-Gaussian families and experimentally control the longitudinal on-demand dynamics of the skyrmions. This work redefines the topological stability of optical skyrmions, breaks limits and reduces the requirement for manipulating topologically structured light for practical multidimensional implementation of topologically robust information technologies.
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All authors Zan Zhang, Zhujun Ye, Zhenyu Guo, Zihan Liu, Zhuoyue Sun, Zijing Zhang, Jiantao Ma, Katsuya Inoue, Yijie Shen, Dongmei Deng

Quantum Physics

Robust Pretty Good Measurement via Hybrid Classical-Quantum Pseudoinverse Approximation and Circuit-Level Realization

Bikash K. Behera, Andrés Camilo Granda Arango, Giuseppe Sergioli et al. (+1 more)

Pretty Good Measurement (PGM) is a near-optimal strategy for quantum state discrimination, but its practical realization becomes unstable when the ensemble operator is singular or ill-conditioned. We introduce a numerically robust PGM formulation based on the Moore-Penrose pseudoinverse, replacing the standard inverse square root with a threshold-regularized variant that remains well-defined across different spectral regimes. We develop a hybrid classical-quantum framework that combines pseudoinverse-based spectral preprocessing with quantum circuit realizations using block-encoding and spectral-transformation techniques. The framework incorporates support awareness, yielding physically meaningful measurement operators even in rank-deficient cases, and employs oblivious amplitude amplification to improve circuit-level success probabilities. Extensive numerical and circuit-level simulations show close agreement between theoretical predictions and quantum circuit outputs. Experiments on synthetic and real datasets, including ill-conditioned and degenerate scenarios, demonstrate stable discrimination performance where standard PGM becomes numerically unstable. The results establish a practical hybrid classical-quantum framework for robust quantum state discrimination and extend previous circuit-based implementations of the PGM testing stage toward pseudoinverse-aware measurement design.
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All authors Bikash K. Behera, Andrés Camilo Granda Arango, Giuseppe Sergioli, Roberto Giuntini

Mathematical Physics · Cross-listed from math.PR

Scaling limits of the single-curve interface and outermost loops in the planar random field Ising model

Fenglin Huang, Léonie Papon and Aoteng Xia

We prove that the interface separating $+1$ and $-1$ spins in the near-critical planar random field Ising model (RFIM) with Dobrushin boundary conditions has a scaling limit, whose law is conformally covariant and almost surely absolutely continuous with respect to SLE$_3$. The limiting curve can be seen as a massive version of SLE$_3$ in the sense of Makarov and Smirnov, but in a random environment. We then show that the outermost spin loops of the near-critical planar RFIM with $+1$ boundary conditions have subsequential limits and that any of these limits is almost surely singular with respect to CLE$_3$. This dichotomy between absolute continuity of the single interface and singularity of the outermost loops reflects the fact that a single interface does not explore enough of the magnetization field of the near-critical RFIM to detect the singularity of this field with respect to the critical Ising magnetization field, whereas the outermost spin loops do.
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Materials Science

Decoding Crystallographic Surface Chirality from Real Space and Momentum Space Images by Machine Learning

Chetana Badala Viswanatha, Ka Man Yu, Benito Arnoldi et al. (+6 more)

Intrinsically chiral metal surfaces, where handedness arises from the asymmetric step-kink-terrace topology of high-Miller index planes, are model systems for enantiospecific catalysis, sensing, and spintronics. Yet no consistent method exists to classify their handedness directly from experimental observables, without prior knowledge of crystallographic indices. Here, we report a dual-domain machine learning framework that recognizes handedness in chiral metal surfaces from two independent image representations: atomic structure models in real space and simulated momentum-resolved photoemission maps of Fermi surface projections in reciprocal space. A ResNet18 model pretrained on general image data is fine-tuned for chirality classification independently on both image representations and achieves meaningful classification accuracy for both real space and reciprocal space images. However, the Fermi surface classifier significantly outperforms the real space classifier. Critically, the reciprocal space classifier, trained only on synthetic images, correctly identifies synchrotron-acquired experimental Angle-Resolved Photoemission Spectroscopy (ARPES) maps of Cu(643)$^R$ and Cu(643)$^S$. The stronger performance in momentum space, as well as the transfer to experimental data, shows that handedness is encoded more globally and robustly in the electronic structure than in the spatially localized kink-site geometry. These results establish ARPES as a quantitative readout of crystallographic surface chirality and suggest a scalable route to identify chiral metal surfaces relevant to spin-selective phenomena.
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All authors Chetana Badala Viswanatha, Ka Man Yu, Benito Arnoldi, Anagha Aravind, Aaruni Kaushik, Jannis Lessmeister, Martin Aeschlimann, Benjamin Stadtmüller, S. Harshini Tekur

Materials Science

A first-principles approach for predicting infrared optical properties of solids

Sreerag Sundaram, Ziqi Guo, Dudong Feng et al. (+2 more)

We present a simplified formalism for predicting infrared optical constants from first-principles calculations. Addressing limitations of the widely used four-parameter semi-quantum Lorentz model, the proposed approach bridges the gap between the harmonic three-parameter model and full self-energy-based methods. By incorporating essential anharmonic effects including four-phonon scattering and phonon renormalisation, the model provides an efficient and accurate alternative while maintaining low computational cost. The frequency-dependent refractive indices of MgO and rutile TiO$_2$ are computed and compared with experimental data, demonstrating good quantitative agreement. The framework offers a practical approach for predicting optical properties of materials across a wide range of materials.
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All authors Sreerag Sundaram, Ziqi Guo, Dudong Feng, Karthik Sasihithlu, Xiulin Ruan

High Energy Physics (Phenomenology)

Electroweak precision physics via angular distributions in hadronic $\tau$ decays

E. Estrada, E. Passemar, S. Paz et al. (+2 more)

Hadronic tau decays provide a unique low-energy laboratory for the charged-current interaction between quarks and leptons. Their use as an electroweak precision sector is, however, limited by nonperturbative QCD dynamics in the resonance region, encoded in hadronic form factors. In this work we show that angular information in two-hadron tau decays can be used to construct observables in which these form factors cancel, leading to first-principles Standard Model predictions up to light-quark-mass and radiative corrections. We derive the fully differential distributions for arbitrary two-pseudoscalar final states, including tau polarization, and extend them to the Weak Effective Field Theory at linear order in new-physics couplings. We then illustrate our strategy with several benchmark observables, for both unpolarized and polarized taus, whose Standard Model predictions can be obtained without modelling the dominant hadronic form factors and which receive characteristic beyond-the-Standard-Model corrections, in particular from tensor currents. These results provide concrete targets for Belle II, polarized-tau proposals such as Chiral Belle, and future high-statistics facilities, including super-tau-charm factories and FCC-ee, to test the electroweak structure of hadronic tau decays.
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All authors E. Estrada, E. Passemar, S. Paz, A. Rodríguez-Sánchez, P. Roig

Pattern Formation and Solitons

Self-similar asymptotics in the decay problem for the Volterra lattice with zero boundary condition

V.E. Adler and B.I. Suleimanov

The article is devoted to the problem of decay of initial stationary state for the Volterra lattice with zero boundary condition. We show that this process is asymptotically self-similar and calculate the propagation velocity of the decay wave, the leading terms of the asymptotics and corrections, in the main and transition sectors of the wave.
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Optics

Sub-8-nm resolution AKB-mirror-based hard X-ray ptychography via generalized Wirtinger projections

Jie Dong, Liang Zhou, Zhongzhu Zhu et al. (+6 more)

Hard X-ray ptychography has become increasingly essential in both the life and physical sciences. However, pushing resolution down to a few nanometres often requires highly customized, chromatic diffractive or refractive X-ray nanofocusing optics, significantly limiting the practical broadband energy-scan applications. Here, we present the first known hard X-ray ptychographic imaging with a half-pitch resolution below 8 nm using total-reflection Advanced Kirkpatrick-Baez (AKB) mirror nanofocusing optics at the high energy photon source (HEPS), with clear potential for further extension. Despite leveraging the benefits of enhanced instrumentation, such as the high coherent flux of 4th-generation diffraction-limited storage rings (DLSR), state-of-the-art beamline X-ray optics and detectors, this is made possible by developing a reconstruction algorithm termed Generalized Wirtinger Projections (GWP). We derive the theory of GWP and experimentally demonstrate its capability for improved partial-coherence reconstruction and enhanced spatial resolution over conventional methods through imaging experiments on a Siemens star test chart at 12.4 keV. GWP provides a highly compact framework for jointly accounting for multiple coupled uncertainties that degrade resolution, enabling straightforward extension to other imaging modalities, such as burst ptychography, while delivering nearly an order-of-magnitude improvement in GPU memory efficiency. Furthermore, the ability to combine nanometre-scale spatial resolution with the inherently achromatic nanofocusing optics demonstrated in this work potentially opens new opportunities for in situ or operando broadband, energy-scan 3D spectroscopic imaging with element- or chemical-state specificity in complex environments at the nanoscale, holding significant promise for a wide range of applications from electronics and energy science to neuroscience.
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All authors Jie Dong, Liang Zhou, Zhongzhu Zhu, Han Xu, Aiyu Zhou, Xuan Wang, Shuo Wang, Xiao Li, Yuhui Dong

High Energy Astrophysical Phenomena

Multi-Epoch X-Ray Detection of SLSN-I 2018bsz: Constraints on the Powering Mechanism and Ejecta Structure

Julia Ahlvind, Josefin Larsson, Dennis Alp et al. (+1 more)

SN 2018bsz is the closest known stripped superluminous supernova (SLSN-I) to date, making it an ideal laboratory for investigating the physical mechanisms powering this class of extreme explosions. We present a multi-epoch X-ray spectroscopic study of SN 2018bsz based on four Chandra observations followed by one XMM observation, spanning 87 to 1253 days after explosion. The source is detected at all Chandra epochs and is also tentatively detected in the late XMM observation, although more uncertain due to nearby contaminating sources. Regardless of the XMM detection, this makes SN 2018bsz the second X-ray detected SLSN-I and the third X-ray detected SLSN overall. We explore potential power sources for the observed X-ray emission and find that a millisecond magnetar central engine underpredicts most of the observed X-ray luminosities and fails to reproduce the relatively flat light curve. Accounting for ejecta absorption further increases the discrepancy. While asymmetries and magnetar-driven ionization could reduce the effective absorption, ionization breakout is expected years after our observational window. Instead, the observations are more readily explained by early-time interaction between the ejecta and the circumstellar medium, while the magnetar emission is absorbed by the ejecta. This scenario is supported by the flat temporal evolution, previous optical results, and inferred mass-loss rates which resemble those of stripped supernovae that later evolve into interacting systems. Our results thus favor the scenario where SN 2018bsz is part of a distinct group of SLSNe-I, where interaction is crucial for the strong emission.
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All authors Julia Ahlvind, Josefin Larsson, Dennis Alp, Ragnhild Lunnan

Astrophysics of Galaxies

Beyond the Fundamental Metallicity Relation: galaxy sizes encode the link between inflow and metallicity

N. F. Boardman, V. Wild, D. Scholte et al. (+3 more)

Gas-phase chemical abundances are key observable consequences of galaxy evolution, being intrinsically tied to galaxy formation histories. Gas metallicity rises with increasing stellar mass ($\mathrm{M_*}$), forming the well-known mass-metallicity relation (MZR). MZR residuals have separately been shown to anti-correlate with star-formation rate (the “fundamental” metallicity relation), with gas mass and with optical size, but no single analysis has considered all trends together. We thus perform a combined analysis of all three trends, utilizing optical MaNGA integral field spectroscopy, HI-MaNGA gas masses, and MaNGA DynPop dynamical masses. We estimate inner gas masses for $\sim$1500 star-forming galaxies, finding this to be the most important parameter after $\mathrm{M_*}$ in predicting gas metallicities. We obtain equivalent results for stellar metallicities and gaseous N/O, suggesting that current inner gas masses are intrinsically linked to long-term chemical evolution histories. We show that more compact galaxies have lower dynamical masses, challenging suggestions that deeper gravitational potentials confer higher metallicities. We find a strong correlation between inner gas mass and galaxy size, meaning that short term inflow fluctuations cannot be responsible for the MZR residuals. With chemical evolution models, we show that our results can instead be explained by differences in long-term inflow histories. The earlier inflow histories of compact galaxies lead to lower gas masses and more rapidly declining gas reservoirs at late times, leading to higher metallicities. At fixed stellar mass, galaxy size therefore encodes the link between halo assembly histories, long-term gas inflow histories, current gas reservoirs and metallicity.
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All authors N. F. Boardman, V. Wild, D. Scholte, K. Wang, N. Vale Asari, A. Saintonge

Astrophysics of Galaxies

Grain alignment and dust evolution physics with polarisation (GRADE-POL). II. On the physical basis of Serkowski and super-Serkowski polarisation spectra

Le Ngoc Tram, Thiem Hoang, B-G Andersson et al. (+4 more)

Optical-to-near-infrared interstellar polarisation, induced by aligned dust grains, generally follows a convex wavelength dependence, known as the Serkowski relation. However, observations in the ultraviolet (UV) and at [mid-]infrared wavelengths have indicated that some of the spectra do not follow this relation. Specifically, about 25% show an excess in the degree of polarisation at mid-UV wavelengths ($\lambda^{-1} > 3\,\rm \mu m^{-1}$), referred to as the super-Serkowski polarisation. For this study, we re-examined both the Serkowski and super-Serkowski spectra based on the joint effect of paramagnetic relaxation, known as the Davis-Greenstein (DG) and radiative torque (RAT) alignment. We used the observational data for HD 30614, HD 204827, HD 37903 and HD 161056 to constrain our modelling. We examined two types of radiation fields: one derived from the scaled interstellar radiation field and the other originating from a B-type star. For the super-Serkowski spectra of HD 30614 and HD 204827, our model demonstrates that RAT alignment enhanced by radiation produced from a B-type star below the Lyman limit ($\lambda=912\r{A}$) can reasonably explain the observations and that a combination with the DG alignments results in a better fit for $\lambda^{-1}\geq 5.5\,\rm \mu m^{-1}$. For the Serkowski spectra in HD 37903 and HD 161056, only the RAT alignment by itself under the typical interstellar radiation field above the Lyman limit, within a typical cold neutral medium, can account for the observed spectra, with a combination of a very inefficient DG alignment. The capacity of our model to predict the starlight polarisation spectrum from infrared to far-UV is thus a promising tool for interpreting future missions that observe spectrophotometry in the UV bands.
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All authors Le Ngoc Tram, Thiem Hoang, B-G Andersson, Alex Lazarian, Lapo Fanciullo, Bao Truong, Archana Soam

Quantum Physics

Hamiltonian-Aware ADAPT Variational Quantum Eigensolver for Molecular Ground-State Simulation

Runhong He, Chao Liu, Xin Hong et al. (+5 more)

Designing compact ansätze in Variational Quantum Eigensolver (VQE) is crucial for solving energetic problems of practical molecules on near-term quantum devices. However, existing Adaptive Derivative-Assembled Pseudo-Trotter (ADAPT) ansätze face two challenges: improper operator selection and accumulation of degraded operators. In this paper, we propose the Hamiltonian-Aware (HA) ADAPT-VQE algorithm to address these issues. First, we establish a novel excitation operator selection criterion. It breaks the local constraint of existing criteria by incorporating Hamiltonian information, prioritizes physically meaningful excitation operators, and incurs no extra classical or quantum computational overhead. Furthermore, we develop a problem-adaptive method for discriminating and pruning redundant excitation operators stemming from improper selection and inevitable degradation. This method balances redundant operator pruning and convergence guarantee, and is applicable to ansätze with arbitrary scales. Systematic numerical experiments on typical strongly correlated molecular systems demonstrate that our HA-ADAPT-VQE avoids energy plateaus and outperforms baseline algorithms in terms of energy error, ansatz size, and measurement cost. This work offers an efficient, robust ansatz construction paradigm, facilitating the development and practical deployment of large-scale VQE in quantum chemistry.
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All authors Runhong He, Chao Liu, Xin Hong, Qiaozhen Chai, Junyuan Zhou, Ji Guan, Guolong Cui, Shenggang Ying

Chemical Physics

Model structures and electron transfer properties of conductive nickel-organic nanoribbons in cable bacteria

Oliver Russell, Martijn A. Zwijnenburg, Filip J.R. Meysman et al. (+1 more)

Cable bacteria are multicellular bacteria capable of centimeter-scale conduction through a regular fiber network embedded in their cell envelope. The conductivity of these fibers is extremely high for biological materials, and rivals that of the best synthetic conductive polymers, but the underlying electron transport mechanism remains elusive. Recent microscopic and spectroscopic evidence indicates that each fiber embeds a bundle of intertwined nanoribbons as the conductive conduit. Each nanoribbon consists of a one-dimensional nickel-organic framework, built from stacked nickel bis(1,2-dithiolene) oligomers (NiBiD units) as molecular building blocks. Here we performed DFT calculations of nanoribbon model structures, in order to characterize their electronic properties, examine potential stacking configurations and verify whether these structures can support efficient conductance. Our simulations indicate that nanoribbons are comprised of tightly stacked AA or AB-type packings of NiBiD units. In the most energetically stable structure (AB-type) some Ni centers are predicted to be 5-fold coordinated due to formation of an inter-layer Ni-S coordination bond. In several energetically low-lying structures, the electronic coupling between neighboring molecules exceeds the critical threshold for charge delocalization permitting efficient charge transport beyond small polaron hopping. Our results hence reveal that nanoribbons based on NiBiD units exhibit favorable charge transfer properties that may explain the unusually high conductivities measured in the fibers of cable bacteria.
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All authors Oliver Russell, Martijn A. Zwijnenburg, Filip J.R. Meysman, Jochen Blumberger

High Energy Astrophysical Phenomena

Deep optical spectroscopic monitoring of the pulsating ULX NGC 1313 X-2 with longslit Gemini observations

Rajath Sathyaprakash and Timothy. P. Roberts

This study reports the nature of the companion star to the pulsating ULX NGC 1313 X-2, using long-slit spectroscopic data from Gemini-South observations, based on archival data from 2009. After stacking flux-calibrated spectra from ten nights of observations and fitting the spectra with stellar templates, we find a possible Balmer break in the GMOS-S spectrum below 4000 Angstroms, which is suggestive of an A-type supergiant donor. Using the inferred stellar radii, we report updated constraints on the orbital parameters of the system and on the nature of the binary. We also add some information on the accretion disc size scale by studying the X-ray and optical variability using the lag-frequency spectrum and corroborate on results from earlier studies for the gas bubble expansion rates by modelling the [O III] emission line profiles, allowing constraints on the kinetic power of the wind/jet relative to the accretion power. This study also expands on previous efforts to study the formation history of the binary using multi-wavelength observations.
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Materials Science

Disentangling the origin of degradation in perovskite solar cells via optical imaging and Bayesian inference

Akash Dasgupta, Robert D. J. Oliver, Manuel Kober-Czerny et al. (+5 more)

Machine learning and computational inference, coupled with experimental data, promise to significantly accelerate our rate of learning in most scientific disciplines. In this study, we develop tools that connect microscopic observations to macroscopic device behaviour, a capability that is essential for accelerating the design of durable energy materials. To this end, we introduce a novel approach that integrates photoluminescence imaging with drift diffusion simulations to understand operation and degradation in fully fabricated perovskite solar cells. By employing Bayesian inference, we generate "inferred maps" of parameters that govern recombination processes present in devices. We track these parameter maps while the devices are aged (70 {\deg}C, full spectrum sunlight) to analyse their temporal evolution during degradation. Notably, our approach allows us to distinguish between degradation occurring at the hole or electron transporting layer interface, or within the bulk. Our analysis reveals pronounced spatially non-uniform degradation, with significant macroscopic heterogeneity observed in the optoelectronic parameter maps. We pinpoint the greatest degradation observed in specific regions to stem from the perovskite/transport layer interfaces. Finally, we demonstrate that an amino-silane molecular passivation treatment suppresses this degradation, highlighting its specific role in enhancing device stability. Our approach offers valuable insights for future device fabrication and is a clear exemplification of how advanced Bayesian inference can significantly increase the value of experimental data.
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All authors Akash Dasgupta, Robert D. J. Oliver, Manuel Kober-Czerny, Charlie H. G. Nicholls, Xueli Cao, Yen-Hung Lin, Alexandra J. Ramadan, Henry J. Snaith

Classical Physics

A Magnetic Torsional Pendulum for Exploring Forced Resonance, Parametric Resonance, and Parametric Amplification

Wenqing Xie, Jiahao Wu and Yujun Shi

We present a magnetic torsional pendulum that provides a unified experimental platform for investigating forced resonance, parametric resonance, and degenerate parametric amplification in the undergraduate laboratory. The system consists of a permanent magnet suspended by thin wires and driven by externally applied magnetic fields generated by Helmholtz coils. By independently controlling a direct driving field and a periodically modulated bias field, the apparatus can realize ordinary forced oscillations, parametric excitation, and phase-sensitive parametric amplification within the same physical system. A miniature wireless gyroscope embedded in the pendulum bob enables direct measurement of the angular velocity and provides convenient real-time acquisition of quantitative dynamical data. A unified equation of motion is derived to describe all three operating regimes. Experimental studies of forced resonance, parametric resonance, and phase-sensitive parametric amplification are compared with theoretical predictions and numerical simulations. The measurements reproduce the characteristic features of all three phenomena and illustrate the influence of nonlinear effects on the system dynamics. The apparatus combines a simple mechanical design, low-cost instrumentation, and highly visible motion. By allowing direct comparison of different resonance mechanisms and their underlying energy-transfer processes,, it provides an accessible platform for studying oscillation theory, nonlinear dynamics, and parametric phenomena in advanced undergraduate laboratories.
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High Energy Physics (Phenomenology)

Correlation Between Proton Decay Channels and the Axion Mass in an Extended SU(5) GUT

Naoyuki Haba, Keisuke Nagano, Yasuhiro Shimizu et al. (+1 more)

We study a renormalizable SU(5) grand unified theory (GUT) supplemented by a 45-dimensional Higgs field and a DFSZ axion sector, imposing a Georgi–Jarlskog flavor structure at the unification scale. We perform a one-loop gauge coupling unification analysis, explicitly including the threshold masses of the light multiplets arising from the 45-dimensional Higgs field. This analysis identifies the viable region in the $(M_{\mathrm{GUT}},M_{S_1})$ parameter space. Through the relation between the unification and PQ scales, this region yields correlated predictions for the QCD axion mass. The Georgi–Jarlskog assumption substantially reduces the flavor ambiguity of the dimension-six baryon-violating operators, enabling robust constraints and predictions not only for antineutrino modes but also for charged-lepton proton decay modes such as $p \to e^+ \pi^0$. We present the combined implications for proton decay and axion searches, showing how the GUT-selected parameter region maps onto the axion mass, the axion-photon coupling, and the axion-induced EDM coupling.
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All authors Naoyuki Haba, Keisuke Nagano, Yasuhiro Shimizu, Toshifumi Yamada

High Energy Physics (Theory)

The Graviton Propagator in Asymptotically Safe Gravity with Non-Local Form Factors

Emiliano Maria Glaviano

We analyze the flow of the background graviton propagator driven by the running of asymptotically safe form factors in four-dimensional quantum gravity at quadratic order in the curvature expansion. We construct the propagator in the $k=0$ limit and investigate its momentum dependence. The non-local form factors are then analytically continued to Minkowski spacetime, from which the corresponding Minkowskian propagator is obtained. We find a single pole at $q^2=0$ with positive residue and no additional ghost poles at this level of approximation. The corresponding Newtonian potential is found to be regular at $r=0$.
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Solar and Stellar Astrophysics

Field line slippage rate signatures in nonlinear force-free field extrapolations

Sage Stanish and David MacTaggart

Magnetic reconnection plays a central role in solar flares and coronal mass ejections. Identifying where reconnection is physically active within coronal magnetic field models is a key part of magnetic field analysis. We investigate the field line slippage rate as a physics-weighted proxy for three-dimensional reconnection in nonlinear force-free field (NLFFF) extrapolations. The slippage rate measures the instantaneous deviation of magnetic field lines from ideal evolution, due to non-ideal terms in Ohm's law, providing a direct link between magnetic geometry and reconnection physics. For NLFFFs, we show that the resistivity-induced slippage rate is governed by cross-field gradients of the field-aligned twist, thus establishing a clear connection between current structure and reconnection signatures. We further examine its relationship to the squashing factor $Q$, used to identify quasi-separatrix layers (QSLs). By deriving a scaling estimate, we demonstrate that strong magnetic squashing amplifies slippage only insofar as it produces small transverse length scales; large values of $Q$ alone do not guarantee significant reconnection. We apply this framework to a sequence of NLFFF extrapolations of NOAA active region 11158 spanning the X2.2 flare of 15 February 2011. The slippage rate reveals enhanced reconnection signatures associated with distinct phases of the active region's evolution. In comparison with the squashing factor, we show that the field line slippage rate provides a physics-weighted complement to QSL analysis, distinguishing between regions that are geometrically favourable for reconnection and those where reconnection is physically significant.
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High Energy Physics (Phenomenology)

Mass spectra and electromagnetic characteristics of the $K^{(*)}\bar D^{(*)}$ and $K^{(*)}{D}^{(*)}$ molecular tetraquarks from the coupled-channel dynamics

Jia-Ning Cui and Fu-Lai Wang

Motivated by the observation of numerous charmed-strange hadrons lying close to the $K^{(*)}\bar D^{(*)}$ and $K^{(*)}D^{(*)}$ thresholds, we systematically investigate their mass spectra and electromagnetic characteristics, explicitly incorporating the $S$-$D$ wave mixing and coupled-channel effects. For the mass spectra, we employ the one-boson-exchange model and obtain several promising $K^{(*)}\bar D^{(*)}$ and $K^{(*)}D^{(*)}$ molecular candidates awaiting future experimental confirmation. The coupled-channel dynamics is found to play an essential role: it not only enhances binding in existing channels but also generates new loosely bound states that are absent in the single-channel approximation. Regarding the electromagnetic characteristics, we discuss the M1 radiative decay widths and magnetic moments of these charmed-strange molecular tetraquarks based on our obtained mass spectra and spatial wave functions within the constituent quark model. Our results demonstrate that the electromagnetic observables serve as valuable discriminants for clarifying the nature of these hadronic molecules. We encourage experimental collaborations to focus on such predicted charmed-strange molecular tetraquark candidates, especially the genuinely exotic $K^{(*)}\bar D^{(*)}$ states comprising four different flavors with valence quark content $\bar c \bar s u d$.
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Optics

Reservoir-controlled electromagnetically induced gratings in a weakly driven two-level medium

Amjad Hussain, Hamid Arian Zad, Amjad Sohail et al. (+3 more)

We theoretically investigate the transmission and diffraction of a weak probe field from an electromagnetically induced grating formed in a weakly driven two-level medium coupled to engineered quantum reservoirs. Using a perturbative solution of the optical Bloch equations in the weak-driving regime, we analyze how normal-vacuum, thermal, and broadband squeezed-vacuum environments modify the probe susceptibility and consequently reshape both the spatial transmission function and the far-field diffraction patterns. We show that reservoir statistics have a pronounced impact on the diffraction response by altering the amplitude and phase of the induced grating. Thermal reservoirs enhance the transmission modulation and increase the intensity of the dominant diffraction orders, whereas squeezed-vacuum reservoirs generate strongly phase-sensitive modifications that selectively redistribute optical power among diffraction channels. We further demonstrate that the detuning between the squeezed reservoir and the driving field provides an efficient mechanism for controlling diffraction directionality, leading to substantial amplification of selected angular orders. In two-dimensional geometries, squeezed-vacuum correlations produce highly structured phase landscapes and strongly anisotropic diffraction patterns, enabling directional enhancement of specific diffraction channels while suppressing others. These results establish reservoir engineering as a versatile approach for controlling transmission, diffraction efficiency, and angular selectivity in minimal two-level systems, with potential applications in programmable photonic devices, beam steering, and quantum optical platforms.
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All authors Amjad Hussain, Hamid Arian Zad, Amjad Sohail, Hazrat Ali, Michal Jaščur, Saeed Haddadi

Optics

Intelligent Perception Assisted Light Modulation for real-time and program-free nanofabrication and particle manipulation

Weixin Zhu, Hanyu Guo, Chen Zhang et al. (+7 more)

In this paper, we present an Intelligent Perception-Assisted Light Modulation (IPALM) technique, for femtosecond laser nanofabrication and particle manipulation. IPALM technique integrates real-time hand-motion recognition with dynamic spatial light modulation to achieve programming-free laser beam control. In contrast to the conventional programmed laser fabrication techniques which need setup a project prior to fabrication, IPALM offers a direct "mind-to-matter" pathway for laser nanostructuring and biological cells handling with high flexibility and multiple degree of freedom. In nanofabrication, IPALM provides high resolution with feature dimensions down to 280 nm. By mind-driven hand gesture control, the laser beam is regulated to enable direct writing of micro/nanostructures with a minimum feature size down to 280 nm via IPALM. In precise particle manipulation, multiple cells can be simultaneously moved to achieve cell coalescence. With these examples, IPALM showcases its potential for applications in photonics, biomedicine, and microfluidics, for high-dimension and flexible laser applications.
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All authors Weixin Zhu, Hanyu Guo, Chen Zhang, Fang Yang, Ce Zhang, Lijing Zhong, Jianrong Qiu, Kaige Wang, Jintao Bai, Wei Zhao

Astrophysics of Galaxies

Chemical signatures from the first stars embedded in metal-poor gas in galaxies at cosmic dawn

Clara L. Pollock, Kasper E. Heintz, Elka Rusta et al. (+15 more)

The first generation of stars formed from pristine, neutral hydrogen gas. The most massive of these exploded as supernovae within a few million years of their birth, producing the first heavier elements and leaving distinct chemical signatures of their origin in the surrounding medium. However, chemical abundance studies have so far mainly relied on emission-line measurements, which are luminosity weighted and hence biased towards the most recently formed stars. Here we analyse near-infrared, medium-resolution spectroscopy from the JWST-SPURS program of three UV-bright galaxies at redshifts 7.8, 8.6, and 9.3, within the first 650 to 520 million years after the Big Bang. The chemical abundance patterns of the metal lines detected in absorption hint at extremely metal-poor gas, substantially lower than inferred from the emission lines tracing the central, star-forming regions. Further, they all exhibit super-solar [C/O] abundances, which is also imprinted in the averaged spectrum of a larger set of galaxies at similar redshifts. These results reveal the distinct chemical signatures of the first Population III supernovae explosions.
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All authors Clara L. Pollock, Kasper E. Heintz, Elka Rusta, Darach Watson, Stefania Salvadori, Callum Witten, Joris Witstok, Ioanna Koutsouridou, Viola Gelli, Pascal A. Oesch, Gabriel B. Brammer, Andrea Saccardi, Kei Ito, Rashmi Gottumukkala, Dagmar Bergholt, Kasper R. Brooksby, Chamilla Terp, Francesco Valentino

High Energy Physics (Phenomenology)

A generalised-$k_t$ jet algorithm for Deep Inelastic Scattering

Melissa van Beekveld, Silvia Ferrario Ravasio, Alexander Karlberg et al. (+1 more)

We introduce an inclusive generalised-$k_t$ jet algorithm for Deep Inelastic Scattering, defined in the Breit frame and implemented in fjcontrib. The family of algorithms is governed by the usual parameter $p$, which controls the transverse-momentum dependence of the algorithm, as well as by a jet radius parameter $R$. The angular-ordered ($p=0$) version of the algorithm was already presented by some of us, and can be used to formulate observables with simple all-order structures. In this article we investigate phenomenological applications of the algorithms related to the identification of the jet associated with the struck quark, and assess their sensitivity to non-perturbative effects, such as hadronisation. We also perform comparisons with the recent Centauro algorithm.
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All authors Melissa van Beekveld, Silvia Ferrario Ravasio, Alexander Karlberg, Darcy Peake

Mathematical Physics

Chiral Long-Range Order in three Euclidean Lattice Gross-Neveu Models

Simone Fabbri and Leonardo Goller

We prove the existence of Long-Range Order in a class of two-dimensional Euclidean lattice Gross-Neveu models with an even number of fermion flavors, covering three standard lattice discretizations, including naive and staggered fermions widely used in numerical studies. By performing a Hubbard-Stratonovich transformation, we map the fermionic systems to bosonic ones and establish Reflection Positivity for the resulting measures. Exploiting this structure, we combine Chessboard Estimates with a Peierls-type contour argument to prove Long-Range Order for the chirally charged fermion-mass bilinear $\overline{\psi}\psi$ at sufficiently small coupling and sufficiently large flavor number. Our analysis is robust with respect to the choice of lattice discretization and applies uniformly across different realizations of the same underlying continuum model. Moreover, we obtain uniform pointwise bounds on the bosonic two-point function, equivalently on the fermionic mass-mass correlator, showing that it is quantitatively controlled by the minimizers of the effective potential. This provides a fully rigorous and non-perturbative demonstration of Long-Range Order in lattice Gross-Neveu models and establishes a direct connection between the rigorous theory and its large-$N$ (mean-field) predictions.
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