Computational Physics
Discovering a well-conditioned analytic continuation problem via dictionary learning
Thomas Chuna, Phil-Alexander Hofmann, Alexander Benedix-Robles et al. (+1 more)
Many fields of physics use
quantum Monte Carlo (QMC) simulations to simulate
quantum systems in imaginary-time $\tau$ and estimate imaginary-time correlation functions (ITCF). However, extracting dynamic $\omega$-dependent quantities from ITCFs is a notoriously difficult task, known as analytic continuation (AC), that amounts to solving an exponentially ill-conditioned inverse problem. Within the AC literature, there are competing
stochastic and regularized approaches, as well as an emerging collection of works using parameterized models like neural networks. Here we transcend the traditional divides between the communities, introducing the regularized
stochastic optimization method (RSOM). This method reformulates AC as a dictionary learning problem, discovering a sparse dictionary to represent the solution. Our approach is motivated by the astounding results dictionary learning has produced in many scientific fields. Remarkably, RSOM discovers a sparse dictionary that maps an ill-conditioned inverse problem to a low-dimensional problem that is well-conditioned. We demonstrate that the method yields competitive results for common synthetic test problems as well as for authentic QMC data from the finite temperature electron gas. This work exposes that a dictionary exists within all
stochastic and regularized methods and that dictionary learning provides a new angle of attack for future AC methods.
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All authors Thomas Chuna, Phil-Alexander Hofmann, Alexander Benedix-Robles, Tobias Dornheim
High Energy Physics (Phenomenology)
Renormalization of the SMEFT to Dimension Eight: Fermionic Interactions II
Supratim Das Bakshi, Mikael Chala and Zhe Ren
We compute the one-loop mixing of bosonic and two-
fermion interactions into two-
fermion operators in the dimension-eight Standard Model Effective Field Theory (SMEFT). Together with the results in arXiv:2106.05291, arXiv:2205.03301, arXiv:2409.15408, and arXiv:2512.21724, this leaves only the mixing of four-
fermion operators into two-
fermion ones as the remaining piece to complete the SMEFT renormalization program at this order.
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General Relativity and Quantum Cosmology
Impact of the Einstein Telescope's duty cycle on the estimation of binary black holes parameters
Luca Negri, Thomas C.K. Ng, Thibeau Wouters et al. (+13 more)
The geometry of the Einstein
Telescope, the proposed next-generation European gravitational-wave observatory, is yet to be finalized. Two competing designs are under consideration: a nested triangular configuration (ET-{\Delta}) and two separated L-shaped detectors (ET-2L). Extensive prior comparisons of ET designs established the scientific landscape using the Fisher-information-
matrix formalism and identified that duty-cycle-induced single-detector operation is precisely the regime where this approximation becomes less reliable, underscoring the need for a refined, principled treatment of the duty cycle. In this manuscript, we build on that foundation by revisiting the comparison with full
Bayesian parameter estimation of gravitational-wave signals from binary black-hole mergers, projected onto a simulated Einstein
Telescope that incorporates a refined duty cycle modelled via continuous-time Markov chains and testing different detector maintenance strategies. We find that the redundancy inherent in the ET-{\Delta} design enables it to maintain at least two operational detectors for the majority of the observing time, whereas the ET-2L configuration is often limited to a single detector. Crucially, we show that, during partial network operation, ET-{\Delta} often outperforms ET-2L, and that the increased multi-detector uptime translates into tighter constraints on the luminosity distance and source-frame component masses. Notably, this remains true even when gravitational-wave events have a lower signal-to-noise ratio in ET-{\Delta} than in ET-2L.
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All authors Luca Negri, Thomas C.K. Ng, Thibeau Wouters, Tim J. Kuhlbusch, Harsh Narola, Robin Chan, Kailib Ryan Doney, Francesco Cireddu, Isaac C. F. Wong, Fabian Gittins, Peter T. H. Pang, Anuradha Samajdar, Achim Stahl, Justin Janquart, Chris Van Den Broeck, Tjonnie G. F. Li
Quantum Physics
Blind Symmetry Matching in Quantum States with Application to Shot-Count Reduction
Mitchell A. Thornton
Measuring a
quantum computation in a basis adapted to a
symmetry it carries reduces the repeated measurements, commonly referred to as “shots”, needed to read a statistical answer. Detecting the
symmetry a
quantum state carries has many uses: certifying a claimed
symmetry, identifying a conserved-charge sector, flagging
symmetry-breaking as an error signature, and selecting a compression or readout basis; shot-count reduction is developed here as one exemplary case. Existing methods assume the
symmetry is known in advance; we remove that assumption. When it is unknown, the carried
symmetry is discovered from the data by a
symmetry test that scores candidate groups, and the largest passing group is exploited as the measurement basis. We state the pipeline precisely, prove the selection rule is unbiased, and charge discovery in full. Two conditions are treated, both detected by the same score with a different projection: a weak condition, commutation with the representation, and a strong condition, confinement to a single charge sector, the distinction drawn in the
quantum-reference-frame literature. A single
circuit, a controlled twirl followed by a SWAP test, discovers both: discarding the group register tests the weak condition, post-selecting it the strong one. The framework is general over finite groups, with cyclic (
Fourier), dihedral, and symmetric-group (Schur-Weyl) examples; strong confinement to the symmetric, or Dicke, subspace is an exponential reduction. Seeded demonstrations show the loop wins net of discovery: weak matching on momentum readout reduces shots by a factor widening from ten to several thousand, and strong matching on a two-system target by a further factor of the subsystem size. Blind
symmetry matching is a practical primitive for the common case where the matched basis cannot be written down in advance.
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Astrophysics of Galaxies
Solitary dwarf galaxy groups as tracers of dark matter halos in the local Universe
Z. S. Yuan, Z. L. Wen and J. L. Han
In $\Lambda$CDM cosmology,
galaxies and clusters form within dark matter
halos and merge in the hierarchical assembly paradigm to form massive systems. Using the released optical survey data, we searched for groups composed solely of
dwarf galaxies, each with a
stellar mass $M_*<10^{9.5}~M_{\odot}$. We identified 14
dwarf galaxy groups with at least 5
dwarf galaxies, all located within a projected radius of 200 kpc and with a line-of-sight velocity of $\pm$300 km s$^{-1}$. We checked photometric and imaging data and found that these 14
dwarf galaxy groups are solitary, with no neighboring massive
galaxies with $M_*>10^{10}~M_{\odot}$ within 500 kpc and within $\pm$1200 km s$^{-1}$. These
dwarf galaxies are gravitationally bound within
halos with a dynamical mass of around $M_{\rm dyn} \sim 10^{12}~M_{\odot}$ and a virial radius of less than 400 kpc. The
stellar mass fractions of these
dwarf galaxy groups with $M_{\rm dyn}>10^{12}~M_{\odot}$ are one magnitude lower than predicted by the canonical
stellar mass and
halo mass relation. These
dwarf galaxy groups, therefore, are indications of dark matter
halos in the local Universe that host only a few newly formed
dwarf galaxies.
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Materials Science
Direct large-area observation of subsurface plastic activity in conditioned copper electrodes
Yinon Ashkenazy, Inna Popov, Victoria M. Bjelland et al. (+2 more)
High-field conditioning is the process by which
radio-frequency structures in particle accelerators and other high-gradient devices reach their operating fields, yet the underlying physical mechanism remains an open question. Models and indirect measurements point to subsurface dislocation dynamics, but large-area structural measurements have been missing. We present electron backscatter diffraction measurements spanning millimeter-scale regions on a copper cathode conditioned at pulsed direct-current fields up to $\sim$80~MV/m in a sloped-anode geometry, which imposes a known gradient of field exposure across a single electrode. Across nine regions of interest spanning this exposure range, the mean intragrain misorientation of field-exposed regions exceeds that of unexposed references by $\sim$75%; the difference is reproduced by three independent misorientation metrics and confirmed by Kolmogorov–Smirnov tests. To our knowledge, this is the first large-area observation of structural differences between conditioned and unconditioned regions of a high-field electrode. The misorientation separates into three tiers (high-field center and edge, low-field periphery, and unexposed reference) that match the spatial profile of the conditioning-state variable $E_S$ predicted by Monte Carlo simulations. These observations point to the evolving subsurface dislocation population as a candidate physical basis of conditioning.
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All authors Yinon Ashkenazy, Inna Popov, Victoria M. Bjelland, William L. Millar, Walter Wuensch
Quantum Physics
When Isolated Quantum Systems Appear Classical
Thiago R. de Oliveira, Pedro S. Correia, Tiago Debarba et al. (+3 more)
The emergence of classical behavior and the origin of thermal
equilibrium are two central problems in the foundations of physics. In the standard accounts, both phenomena are typically explained through interactions with an external environment: decoherence suppresses
quantum interference, while coupling to a thermal bath drives relaxation toward
equilibrium. Over the last decades, however, it has become clear that equilibration and thermalization can arise even in fully isolated
quantum systems, in the operational sense that the expectation values of relevant observables remain close to
equilibrium values for most of the time. Here, we ask whether the same intrinsic equilibration mechanism can also account for the emergence of classical behavior. Using rigorous bounds on equilibration in closed systems, we derive sufficient conditions under which a time-evolved pure state becomes, for most times, operationally indistinguishable from a classical mixture associated with a chosen physical property. We identify two complementary routes to such operational classicality: either the chosen property almost commutes with the system
Hamiltonian or the observables used to probe the system lose access to the remaining coherence after equilibration. Our results show that classical behavior need not be confined to the energy basis and may emerge even when substantial coherence remains present in the
equilibrium state. This establishes a direct connection between two foundational questions: the origin of thermalization in isolated
quantum systems and the
quantum-to-classical transition
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All authors Thiago R. de Oliveira, Pedro S. Correia, Tiago Debarba, Gabriel Dias Carvalho, Raúl O. Vallejos, Fernando de Melo
Mesoscale and Nanoscale Physics
Constriction-induced modulation of charging energy in a quantum Hall cavity
Emily Hajigeorgiou, Arup Kumar Paul, Mario Di Luca et al. (+3 more)
Electronic Fabry-Pérot interferometers (FPIs) operating in the fractional
quantum Hall regime are a key platform for probing anyonic braiding statistics, yet interpreting their interference signals is complicated by Coulomb charging effects, which are commonly treated as parasitic, static properties governed by the cavity's geometry and electrostatics. Here, using a gate-defined
quantum Hall cavity tuned to the Coulomb-dominated regime, we demonstrate that the charging energy is in fact strongly and non-monotonically modulated by the
magnetic field, varying by up to 60% over a range of only 100 mT. The effect appears exclusively when the
quantum point contacts (QPCs) forming the cavity are weakly pinched off, i.e., in the strong cavity-to-lead coupling regime. By correlating the charging energy modulation with the QPC magneto-conductance, we attribute this behavior to field-dependent changes in local compressibility and electrostatic screening between the cavity and the leads, driven by the formation of incompressible fractional
quantum Hall states within the constrictions. This result establishes QPC constrictions of
quantum Hall cavities as active electrostatic elements rather than passive boundaries, revealing a dynamic screening mechanism, with direct consequences for the interpretation of interference measurements and the extraction of anyonic statistics.
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All authors Emily Hajigeorgiou, Arup Kumar Paul, Mario Di Luca, Vladimir Umansky, Moty Heiblum, Mitali Banerjee
Adaptation and Self-Organizing Systems
Noise seeded oscillators: on the role of demographic fluctuations in a multi-populations model
Francesca Di Patti, Duccio Fanelli and Perla Rosi
Stochastic oscillations can emerge from a two-population model as triggered by endogenous finite size fluctuations. Here, an extended dynamical scenario is considered in which a third fluctuating species is added to a proto-typical scheme of neuronal interaction. As we shall prove both analytically and numerically, the third added species can enhance or even suppress the emergence of quasi-cycles, namely the coherent oscillations of the two original populations, as instigated by the demographic noise component. In general, investigating the coupled dynamics of noisy oscillators of the type considered could yield an extended framework for synchronization studies, beyond the pioneering setting introduced by Kuramoto.
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Quantum Physics
Clifford and Haar scramblers yield equal mean fidelity but unequal fluctuations in black hole-inspired teleportation
Sudhanva Joshi and Sunil Kumar Mishra
Quantum information transfer between entangled black holes has inspired many-body teleportation protocols. We study such a protocol without assuming a gravitational dual and ask whether its fidelity requires nonstabilizerness, or magic, in the scrambling dynamics. Because the mean fidelity depends only on the third moments of the scrambler ensemble, zero-magic Clifford scramblers teleport on average as well as Haar-random
unitaries. Solving the protocol exactly at infinite temperature, we find that typical Clifford scramblers approach perfect teleportation while the magic of the complete
circuit vanishes as the inverse system size. The two ensembles nevertheless differ in their fluctuations: the exact Clifford fidelity variance decays only algebraically with system size, whereas the Haar variance is exponentially small. This separation characterizes the ensembles rather than magic itself, since magic added away from the message
qubit can leave every fidelity statistic unchanged. With a decoder uncorrelated with the scrambler, every
unitary 2-design leaves the mean fidelity at the no-transfer value, whatever its magic.
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High Energy Physics (Theory)
Higher-spin self-dual gravity from holomorphic planes in twistor space
Nicolas Boulanger, Yannick Herfray, Lionel Mason et al. (+1 more)
We prove a `nonlinear graviton
theorem' for higher-
spin self-dual
gravity. We consider small deformations of the complex structure of the non-projective twistor space that are bounded in a specified region near the origin and investigate the space $M_{HS}$ of holomorphically embedded complex planes $\mathbb{C}^2$ that intersect the origin. We show that this space is an infinite dimensional complex
manifold with a canonical projection onto a four-dimensional holomorphic self-dual spacetime $\mathcal{M}$, and discuss the geometry induced on this new higher-
spin space. Solutions of higher-
spin self-dual
gravity are then obtained by choosing an
embedding of spacetime $\mathcal{M}$ into higher-
spin space $M_{HS}$, with higher-
spin symmetries arising from the different choices of
embedding. Integrability of the theory is manifested in the form of a Lax pair for the system that we present. We
conjecture that
chiral higher-
spin gravity can similarly be realized by considering deformations that are unconstrained at the origin.
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All authors Nicolas Boulanger, Yannick Herfray, Lionel Mason, Noémie Parrini
Superconductivity
Cavity-enhanced superconductivity in the two-dimensional limit of NbSe2
Hanxiang Zhang, Zexin Feng, I-Te Lu et al. (+13 more)
Vacuum electromagnetic fluctuations have emerged as a means of controlling collective
quantum phases without external driving. Cavity-induced modification of superconductivity has been widely predicted. What sets the size of the effect, and which microscopic channel carries it, remain open. Here we couple few-layer NbSe2 to a terahertz complementary split-ring resonator (CSRR) and show that the enhancement grows sharply on approaching the two-dimensional limit. In
bilayer NbSe2 the superconducting transition temperature rises by 10%, from 3.02 K to 3.41 K, on a cavity resonant at 0.92 THz - roughly four times the shift measured in a ten-layer device at the same resonance. Within a single device the shift maps onto the simulated cavity field profile, falling from 0.39 K at the field maximum to zero outside the resonator, with the lower critical field following the same spatial ordering; because all regions are measured on one continuous flake in a single cooldown, sample-to-sample variation is excluded by construction. The frequency dependence is non-monotonic, with suppression below resonance and maximal enhancement near 0.96 THz.
Quantum electrodynamical density functional theory calculations show that cavity coupling redistributes spectral weight in the Eliashberg function, weakening the total electron-
phonon coupling while hardening the logarithmic average
phonon frequency; competition between the two reproduces a sign change in Tc. These results identify dimensionality, local field amplitude and detuning as the control parameters of cavity-enhanced superconductivity, and point to electron-
phonon reweighting as its microscopic origin.
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All authors Hanxiang Zhang, Zexin Feng, I-Te Lu, Zhiwei Li, Songhao Guo, Qiuyu Shang, Thomas Tan, Xiaodan Lyu, Xiangming Shen, Dening Luan, Mingcheng Panmai, Kenji Watanabe, Takashi Taniguchi, Ranjan Singh, Angel Rubio, Weibo Gao
High Energy Physics (Theory)
Bubble wall velocity and nucleation rates in inverse holographic phase transitions
Francesco Bigazzi, Aldo L. Cotrone, Natalia Pinzani-Fokeeva et al. (+1 more)
We study the dynamics of first-order inverse phase transitions (driven by superheating) at strong coupling, focusing on the top-down Witten-Sakai-Sugimoto model for
holographic QCD. Two cases are considered: the deconfinement transition in the unflavored version of the model and a
chiral symmetry-restoring transition occurring in the deconfined phase of the full theory. In both cases, we imagine driving the system into a metastable phase at high temperature, inducing the nucleation of bubbles of the stable phase. For both classes of transitions, we find the corresponding Euclidean bounce solutions and compute the bubble nucleation rates and the relevant transition parameters. For the deconfinement transition, the large jump in the number of degrees of freedom between the two phases suggests that the bubble wall velocity is parametrically small; we provide a rough estimate of it near the critical temperature. In the case of the
chiral transition, instead, we compute the bubble wall velocity and the friction force exerted on the bubbles employing motivated ansatze and approximations for the steady-state configurations.
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All authors Francesco Bigazzi, Aldo L. Cotrone, Natalia Pinzani-Fokeeva, Tommaso Trabocchi
Optics
High-speed electrically driven liquid-crystal compact optical skyrmion encoder
Yu-Ping Tang, Zhenyu Guo, Ze-Yu Wang et al. (+8 more)
Optical skyrmions possess topological polarization textures that can maintain topological robustness under external perturbations, making them promising carriers for disturbance-resistant optical information transmission. However, existing optical skyrmion generation schemes mostly rely on static optical elements or fixed nanostructures, making high-speed dynamic switching of the topological state difficult. Here, we propose a high-speed switchable optical skyrmion generator based on a patterned
liquid-
crystal spin-orbit device. The device employs the in-plane orientation of
liquid crystals to imprint a fixed Pancharatnam-Berry
geometric phase, while an applied voltage rapidly tunes the
liquid-
crystal retardance, enabling reversible switching between skyrmion and non-skyrmion states. Experimental results show that the device exhibits millisecond electrical response, with bidirectional response times of 1.76 ms and 0.72 ms, corresponding to an ideal cycling rate of approximately 403 Hz, making it the fastest switchable optical skyrmion generator to date. Furthermore, by exploiting this rapid topological refreshing capability, we demonstrate image encoding and decoding, providing a new
liquid-
crystal device platform for high-speed, refreshable, and disturbance-resistant topological optical information transmission.
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All authors Yu-Ping Tang, Zhenyu Guo, Ze-Yu Wang, Le Yu, Long-Yang Wang, Nilo Mata-Cervera, Yu Wang, Ning Wang, Yijie Shen, Ling-Ling Ma, Yan-Qing Lu
Instrumentation and Methods for Astrophysics
Guiding Design Choices for Wide-Field IFS: Trade-Offs Between Replication and Complexity for WST
C. Cudennec, A. Jeanneau, R. Bacon et al. (+7 more)
The Wide-field Spectroscopic
Telescope (WST) is a proposed 12-meter segmented facility optimized for seeing- and Ground Layer Adaptive Optics-limited observations in the visible and designed to operate both a high-multiplex multi-object spectrograph and a panoramic integral field spectrograph (IFS). The WST IFS concept builds on instruments such as MUSE at the VLT (Very Large
Telescope), using field splitters and image slicers to reformat a large field into pseudo-slits feeding spectrographs with two optimized spectral channels. This paper presents the integrated design approach adopted for the IFS, focusing on a trade study of spectrograph architectures. We explore design choices such as pixel pitch, detector format, and camera optical design against throughput, image quality, error budgets, volume, cost. The study adds one ecological metric: the carbon footprint of building each spectrograph, to inform design sustainability. The study also explores the potential of curved detectors. Early results suggest that many simpler spectrographs outperform fewer complex units technically and economically.
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All authors C. Cudennec, A. Jeanneau, R. Bacon, T. Lépine, M. Lehnert, R. Giroud, J-E. Migniau, D. Lee, R. de Jong, L. Fréour
High Energy Astrophysical Phenomena
2D magnetohydrodynamic jet simulations: properties of recollimation shocks
Stella Boula, Fabrizio Tavecchio, Gianluigi Bodo et al. (+2 more)
Recollimation shocks are a frequent outcome in overpressured relativistic jets and are crucial for interpreting stationary features in Active
Galactic Nuclei. The precise influence of
magnetic fields on jet stability, energy dissipation, and variability remains debated, particularly as different field configurations can significantly alter shock properties and the onset of fluid instabilities. We perform a study of 2D axisymmetric RMHD jets to quantify how the ambient density contrast ($\nu$), pressure ratio ($P$), magnetization ($\sigma$), and
magnetic pitch parameter ($\alpha$) govern the formation and strength of the first recollimation shock. We also assess how these parameters create the local
geometric conditions favorable for the centrifugal instability (CFI), utilizing linear theory as a diagnostic. We find that the jet's global geometry is affected by the
magnetic pressure. The recollimation distance decreases monotonically with increasing magnetization $\sigma$, as increased
magnetic forces immediately limit jet expansion. Remarkably, in the magnetically dominated regime, the ratio of the magnetized recollimation distance ($z_{\rm MHD}$) to its purely hydrodynamic counterpart ($z_{\rm HD}$) converges onto a power-law scaling, $z_{MHD}/z_{HD} \propto (B_0^2/P_{ext})^{-1/3}$, where $B_0$ the initial
magnetic field and $P_{ext}$ the external pressure. Jets with high density contrast relative to the ambient medium or high internal pressure further enhance field compression. Furthermore, synthetic synchrotron maps show that a dominant toroidal field yields highly boosted, localized emission
knots, whereas a strong poloidal field creates a diffuse profile and shifts the recollimation zone downstream. Regions susceptible to CFI are determined primarily by the local $\sigma_{\text{tor}}/\Gamma^2$ profile and streamline
curvature created during recollimation.
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All authors Stella Boula, Fabrizio Tavecchio, Gianluigi Bodo, Nektarios Vlahakis, Paolo Coppi
Materials Science
AdsMind: A Physics-Grounded Multi-Agent System for Self-Correcting Discovery of Adsorption Configurations on Heterogeneous Catalyst Surfaces
Zongmin Zhang, Yuyang Lou, Bowen Zhang et al. (+6 more)
Identifying the lowest-energy surface-adsorbate configuration is critical for modeling heterogeneous catalysis, yet exhaustive exploration with ab initio calculations is computationally prohibitive. Machine-learning force fields (MLFFs) accelerate structural relaxation but leave the search over the vast configurational space a major bottleneck, and open-loop large
language model (LLM)
agents lack a physics-grounded feedback mechanism to correct erroneous initial guesses. We propose AdsMind (Adsorption configuration discovery with Machine intelligence and relaxation feedback), a closed-loop multi-
agent framework that enables autonomous error correction through MLFF relaxation feedback. Across four LLM backends, AdsMind achieves consistently high search reliability, with success rates of 100% and 98.8% on the
benchmarks AA20 and OCD-GMAE62. Relative to its single-pass (1-Shot) ablation it reduces cross-backend energy dispersion, and it uses only 4.11 and 4.67 MLFF relaxations per case, respectively – an approximately 14-fold reduction over heuristic enumeration baselines. Density functional theory (DFT) validation using VASP/PBE on six representative AA20 systems shows that the reported open-loop Adsorb-
Agent outputs exhibit qualitative adsorption-energy sign errors for molecular adsorbates, whereas AdsMind preserves the correct sign in all tested cases with closer quantitative agreement. AdsMind thus delivers reliability, self-reflection, and interpretability simultaneously, supporting more DFT-informed autonomous chemistry workflows.
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All authors Zongmin Zhang, Yuyang Lou, Bowen Zhang, Junwu Chen, Ryo Kuroki, Xuan Vu Nguyen, Edvin Fako, Lixue Cheng, Philippe Schwaller
Materials Science
Controllable Growth and Characterization of {\alpha}- and {\beta}-phase MnSe by Chemical Vapor Deposition
Jennifer E. DeMell, Elias Kallon, Michael Pedowitz et al. (+3 more)
Manganese selenide (MnSe) is a promising air-stable two-dimensional
magnetic semiconductor for which theory predicts robust ferromagnetism in monolayers with Curie temperatures approaching 250 K. However, the crystallographic phases and
magnetic properties of thin-film MnSe grown by scalable methods remain poorly understood. Here, we demonstrate the controllable growth of ${\alpha}$- and ${\beta}$-phase MnSe on C-face sapphire using a three-zone chemical vapor deposition process with elemental Se and ${MnCl_{2}}$ precursors in an $Ar/{H_{2}}$ atmosphere. Using Raman spectroscopy, atomic force microscopy, scanning electron microscopy, and X-ray photoelectron spectroscopy, we show that our process yields phase-pure ${\alpha}$-MnSe nanorods and ${\beta}$-MnSe triangular flakes with lateral sizes up to 20 ${\mu}m$ and thicknesses of 15-30 nm. Low-temperature photoluminescence of the ${\beta}$-phase films reveals a bandgap of approximately 2.0 eV. Systematic variation of growth parameters shows that precursor vapor pressure, rather than ${H_{2}}$ partial pressure, is the dominant factor controlling lateral flake size. Vibrating-sample magnetometry measurements reveal a $N{\'e}el$ temperature of 53 K in the ${\beta}$-phase films, providing clear evidence of antiferromagnetism in the multilayer regime and establishing MnSe as a tunable platform for 2D spintronic and optoelectronic devices.
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All authors Jennifer E. DeMell, Elias Kallon, Michael Pedowitz, Jimmy C. Kostakidis, Ihteyaz Aqaeed Avash, Kevin M. Daniels
Mathematical Physics
Topology of Bloch Bands from Cauchy Data
Didier Felbacq and Emmanuel Rousseau
In a previous work, the
topology of inversion-symmetric one-dimensional periodic media was characterized through the pole-zero pattern of an impedance-like function associated with Bloch waves. This construction reproduces the Berry–Zak invariant and provides a criterion for topological interface states. In the present work, we give a
geometric interpretation of this formalism. We show that poles and zeros arise naturally from the action of inversion
symmetry on the projectivized space of Cauchy data. The corresponding Dirichlet and Neumann states are identified with the two fixed points of the induced $\mathbb Z_2$ action on the Riemann sphere. The key observation is that Bloch eigenvectors are naturally constructed on the universal covering of the Brillouin circle. The
topology of the associated Real eigenline bundle is encoded in the action of the deck transformation group on lifted eigenvectors. This action is described by a monodromy sign $\rho\in\{\pm1\}$, determined by the inversion representations carried by the band at the fixed points of the Brillouin zone. We show that this monodromy defines a natural rank-one local system over the Brillouin circle. The corresponding Real line bundle is classified by its first Stiefel–Whitney class, which coincides with the associated $\mathbb Z_2$ pole-zero invariant. This establishes a
geometric connection between the pole-zero formalism, Berry–Zak phases, Real bundles and local coefficient systems.
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Mathematical Physics
Bulk-boundary correspondence of (1+1)D symmetric gapped phases
Yizhou Ma, Gen Yue and Tian Lan
We develop an operator-algebraic framework for boundary conditions and bulk-boundary correspondence in one-dimensional gapped phases with categorical
symmetry. Working directly in the thermodynamic limit, we construct half-infinite fusion
spin chains and commuting-projector boundary
Hamiltonians from a
unitary fusion category $\mathcal{C}$, an indecomposable semisimple right $\mathcal{C}$-module category $\mathcal{M}$, a Q-system $Q\in\mathcal{C}$ specifying the bulk phase, and a right $Q$-module $K\in\mathcal{M}_{Q}$, regarded as an object of $\mathcal{M}_{Q}^{\mathrm{op}}$, specifying the boundary. We prove that these
Hamiltonians have unique ground states and that the resulting realization functor $\mathcal{M}_{Q}^{\mathrm{op}}\to\mathrm{BCond}$ is an equivalence, so simple boundary conditions are classified by simple objects of $\mathcal{M}_{Q}$ and general boundary conditions by their finite direct sums. We also give a microscopic formulation of the boundary
symmetry topological field theory using DHR bimodules of the boundary quasi-local
algebra. For a half-infinite fusion
spin chain, the boundary DHR category is monoidally equivalent to $(\mathcal{C}_{\mathcal{M}}^{\vee})^{\mathrm{rev}}$, and the canonical action of the bulk DHR category on it agrees with the categorical action of $Z_1(\mathcal{C}^{\mathrm{rev}})$. Finally, we identify the action of the boundary DHR category on boundary conditions with the categorical action of $(\mathcal{C}_{\mathcal{M}}^{\vee})^{\mathrm{rev}}$ on $\mathcal{M}_{Q}^{\mathrm{op}}$. This yields a one-dimensional bulk-boundary correspondence: the enriched monoidal category describing the bulk is the enriched center of the enriched category describing the boundary.
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Optics
Equivariant Graph Neural Networks Improve Optical Spectra Prediction for Materials Screening
Kasper Helverskov Petersen, François R J Cornet, Martin Ovesen et al. (+3 more)
Scalable prediction of optical spectra is a critical component of high-throughput materials screening for optoelectronic applications such as
solar cells. Existing surrogate models are trained on spectra computed from lower levels of theory or rely on rotation-invariant scalar features, limiting their
geometric expressiveness. We explore the use of equivariant graph neural networks for optical spectra prediction, adapting GotenNet to this task and evaluating it on multiple
datasets including a recently published collection of 10,533 structures with spectra computed at the level of the random phase approximation (RPA). The proposed model outperforms the current state of the art, with the largest gains in the 0-8 eV range and on predicting the static real permittivity, both of particular relevance for thin-film optics.
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All authors Kasper Helverskov Petersen, François R J Cornet, Martin Ovesen, Mikkel Jordahn, Kristian S. Thygesen, Mikkel N. Schmidt
Materials Science
Generalized deformation potential and machine-learning approaches for electron-phonon coupling and thermoelectric transport in semiconductors
Ransell D'Souza and Ivana Savic
The ability to compute electron-
phonon coupling from first principles, using density functional perturbation theory and interpolation techniques, has enabled predictive calculations of electronic transport coefficients in crystalline materials. However, these methods are still computationally expensive. Here we present two inexpensive methods to obtain thermoelectric transport properties of
semiconductors using a small number of electron-
phonon matrix elements calculated from first principles. The first method combines models for coupling of electrons with different
phonon modes whose parameters are obtained from $\sim 10$
matrix elements per electronic band and
phonon mode calculated from first principles. Within this method, we formulate the acoustic deformation potential model for arbitrary
crystal symmetries and band extrema locations. The second method uses machine learning to interpolate $\sim 100$ electron-
phonon matrix elements per electronic band and
phonon mode on dense reciprocal space grids in the parts of the Brillouin zone relevant for transport. We apply both methods to two-dimensional MoS$_2$ and show very good agreement with the state-of-the-art method. The calculated thermoelectric properties also agree well with experiments. We find that the machine-learning method is more accurate and straightforward to implement compared to the model approach.
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Solar and Stellar Astrophysics
The formation radius of HCN in O-rich asymptotic giant branch stars
L. Marinho, J. P. Fonfría, M. Agúndez et al. (+3 more)
Molecules detected in circumstellar envelopes around asymptotic
giant branch (AGB)
stars are generally well explained in terms of formation under chemical
equilibrium in the
stellar atmosphere or photochemistry in the outer expanding layers. However, several molecules are detected in the inner circumstellar regions with abundances orders of magnitude above the predictions of chemical
equilibrium. Anomalously abundant molecules comprise H2O, NH3, SiH4, and PH3 in C-rich envelopes and HCN, CS, and NH3 in O-rich sources. These molecules are formed by some yet unknown nonequilibrium processes. Aims: We aim to shed light on the nonequilibrium process that enhances the abundance of anomalously abundant molecules in the inner regions of circumstellar envelopes. Here, we focus on HCN in O-rich
stars to constrain its formation radius. Method: We observed the O-rich AGB
stars RCrt and IKTau with ALMA at high angular resolution (HPBW=~0.05") in the J=4-3 line of HCN in both the ground and the \nu_2=1 vibrational states. The radial distribution of the emission was modeled using a large velocity gradient radiative transfer code in which we considered an abundance profile with a central hole. Results: The models with a hole in the abundance distribution of HCN reproduce the specific shape of the radial emission distribution around the two studied O-rich
stars. The best models locate the formation radius of HCN at 4-6 Rstar in RCrt and 3-5 Rstar in IKTau. Conclusion: The formation radius of HCN inferred from observations is consistent with models that invoke shocked-induced chemistry but also with models where photochemistry acts as the solely disequilibrium process. High angular resolution observations of more O-rich
stars and tailored shocked-induced and/or photochemical models are needed to unambiguously unveil the underlying mechanism behind anomalously abundant molecules in AGB envelopes.
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All authors L. Marinho, J. P. Fonfría, M. Agúndez, L. Velilla-Prieto, G. Quintana-Lacaci, J. Cernicharo
Instrumentation and Methods for Astrophysics
Comparative Study of Hollow-Core and Standard Optical Fibers for Astronomy
Malak Galal, Oliver Pineda Suárez, Frédéric Gérôme et al. (+3 more)
Efficient light transmission in the blue-visible regime remains a major limitation for fiber-fed astronomical spectrographs, where low
photon flux and the intrinsic attenuation of conventional silica fibers reduce survey sensitivity and depth. Inhibited-coupling hollow-core fibers (IC-HCFs) with reduced surface roughness offer a promising alternative, providing guidance predominantly in air and enabling significantly lower loss across the visible spectrum. In this study, we present a comparative evaluation of IC-HCFs against standard multi-mode fibers used in current astronomical instrumentation. We assess the throughput loss that occurs due to bending, twisting, or pinching of the optical fibers when moved using one of the robotic fiber-positioner prototypes designed for next-generation
telescopes. These measurements quantify the performance gains offered by IC-HCFs for blue-sensitive spectroscopy and assess their suitability for integration into future survey facilities.
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All authors Malak Galal, Oliver Pineda Suárez, Frédéric Gérôme, Benoit Debord, Fetah Benabid, Jean-Paul Kneib
Instrumentation and Detectors
Prospects for Observing Gravity-gradient Noise and Earthquake Gravity Signals with CHRONOS
Mario Juvenal S. Onglao III, Yuki Inoue and Daiki Tanabe
Ground-based gravitational-wave detectors operating in the sub-Hertz regime are expected to be strongly limited by environmental
gravity-gradient fluctuations, commonly referred to as Newtonian Noise (NN). At the same time, this frequency band provides unique opportunities to probe terrestrial gravitational perturbations associated with seismic and atmospheric processes. In this work, we investigate the feasibility of using the proposed Cryogenic sub-Hz cROss torsion-bar detector with
quantum NOn-demolition speed meter (CHRONOS) as a platform for studying
gravity-gradient noise and detecting
prompt gravitational signals from earthquakes. We model
gravity-gradient contributions from Rayleigh-wave-induced seismic fields, atmospheric infrasound fluctuations, and transient mass redistribution during earthquakes, and project these onto the CHRONOS torsion-bar response. CHRONOS achieves a peak strain sensitivity of order ~1e-18 Hz^(-1/2) near ~2 Hz. Rayleigh-wave NN is found to be the dominant environmental contribution below approximately 0.5 Hz, while atmospheric NN remains several orders of magnitude smaller throughout the frequency range considered. We further assess the detectability of
prompt gravitational signals from earthquakes. For a representative Mw = 5.2 event, sources within approximately 90 km may produce detectable signals. At 40 km distance, we obtain a signal-to-noise ratio (SNR) of approximately 3.62 integrated over the sub-Hz band, with a corresponding strain amplitude reaching the CHRONOS sensitivity curve around 0.2 to 0.6 Hz. The gravitational signal is expected to precede seismic P-wave arrival by several seconds, depending on the assumed propagation velocity. These results demonstrate the potential of CHRONOS to probe both
gravity-gradient noise and transient geophysical
gravity signals in the sub-Hertz regime.
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Optics
Extreme mid-infrared field enhancement and anapoles in high-index plasmonic metamaterials
Zoltan Sztranyovszky, Nicolas Spiesshofer, Caleb Todd et al. (+5 more)
High-refractive-index materials underpin a wide range of optical technologies, including communications, imaging,
lasers, and integrated photonic systems. Here, we demonstrate a self-assembled metamaterial platform based on gold nanoparticle aggregates with nanometer-scale gaps exhibit remarkably high effective refractive indices exceeding 15 in the mid-infrared regime, while simultaneously producing gap-field enhancements of at least two-orders of magnitude. This combination of high refractive index and extreme field enhancement enables exceptionally strong light-matter interactions. We demonstrate this by designing a compact high-index metamaterial device supporting an anapole, which further enhances the nanogap field. By placing
quantum emitters with terahertz transitions inside the plasmonic gaps, we show a stimulated-emission response enhanced by at least three orders of magnitude, highlighting applications in non-linear optics, frequency up-conversion and vibrational strong coupling.
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All authors Zoltan Sztranyovszky, Nicolas Spiesshofer, Caleb Todd, Rakesh Arul, Yeeun Roh, Rohit Chikkaraddy, Jeremy J. Baumberg, Angela Demetriadou
High Energy Physics (Theory)
Post-Carroll Algebra, Conformal Extensions, and Field Theories
Mojtaba Najafizadeh
By incorporating leading $c\,$-dependent corrections to the Carroll transformations, we introduce the “post-Carroll transformations”. We demonstrate that these transformations are consistent with post-Carrollian mechanics \cite{Najafizadeh:2025ksm}; furthermore, they give rise to the so-called “post-Carroll
algebra”. We show that, unlike the Carroll
algebra, this new structure allows for a central charge in higher dimensions; we refer to it as the “Carroll-Bargmann
algebra”. To construct conformal extensions, we first build the conformal extension of the post-Carroll
algebra and study field theories invariant under this
symmetry. We then construct the conformal extension of the Carroll-Bargmann
algebra, referred to as the “Carroll-Schrödinger
algebra”, and demonstrate that it precisely matches the
symmetry algebra of the higher-dimensional Carroll-Schrödinger theory \cite{Najafizadeh:2024imn}. Finally, we derive the general form of two-point functions in a post-Carrollian CFT, which in $1+1$ dimensions exhibits both electric and
magnetic sectors, while in higher dimensions only the
magnetic sector survives.
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General Relativity and Quantum Cosmology
Kiselev black hole and the ultra-slow evaporating behavior
Chen-Hao Wu, Xiao Liang and Ya-Peng Hu
Kiselev solution is a metric that describes black holes immersed in a quintessence-like dark energy background. By introducing a dynamic state parameter $w_q$, the Kiselev solution is supposed to help comprehend the effect of quintessential matter on black holes. In this work, we study the evaporation behaviors of Kiselev black holes. By varying the state parameter $w_q$, we find that the decreasing state parameter lowers the non-final stage temperature and markedly prolongs the evaporation lifetime. We also find that the ultra-slow evaporation mechanism of Kiselev black holes differs vastly from the perfect fluid dark matter (PFDM) black holes and Horndeski black holes, which share the analogous ultra-long lifetime. These results illuminate the effects of dynamic dark energy background on black hole evaporation, provide a potential laboratory to constrain the value of $w_q$, and may complement cosmological and astrophysical observations, e.g., the DESI's preference for thawing dark energy and the observation of exploding black holes based on ultra-slow evaporation.
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Superconductivity
Evidence for Multiband Superconductivity in 2H-NbSeS
K. Yadav, M. Lamba K. Bhattacharya, M. Majumder et al. (+1 more)
The nature of superconductivity in 2H-NbSe2 has generated sustained debate in the recent past. While angle resolved photoemission spectroscopy data have been interpreted as evidence for multiband superconductivity, the data from scanning tunneling microscope experiments relate to strongly anisotropic single-band superconductivity. In the later case, the charge density wave (CDW) order mimics the multigap character. Because the CDW reconstructs the
Fermi surface and modifies the superconducting gap distribution, disentangling intrinsic multiband pairing from CDW-related effects is challenging. To address this issue, we investigate single-crystalline 2H-NbSeS, a mixed-chalcogen analogue of 2H-NbSe2 in which random Se/S substitution suppresses long-range CDW order while preserving the layered
crystal structure P63/mmc. The material becomes superconducting below 6.0 K with moderate
magnetic anisotropy. The upper critical field exhibits a pronounced upward
curvature that cannot be described within a single-band framework but is well captured by a dirty-limit two-band model with a large diffusivity ratio. This indicates strong band-dependent scattering. The in-plane upper critical field exceeds the weak-coupling Pauli limit. Measurements of the lower critical field, superfluid density, and electronic specific heat are consistent with an interpretation of a fully gapped superconducting state with two nodeless gaps of different magnitudes.
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All authors K. Yadav, M. Lamba K. Bhattacharya, M. Majumder, S. Patnaik
Cosmology and Nongalactic Astrophysics
PHANTOM: A MATLAB and Octave Toolbox Connecting Linear Field Statistics to Dark Matter Halo Observables
Mohammad Abu Thaher Chowdhury
We present phantom (Profile and
Halo Analysis for Numerous Theoretical dark Matter Observables), a public MATLAB toolbox and Octave package for calculations that connect the linear density field to dark matter
halo observables. The package combines a flexible cosmology module with linear power spectrum, variance, and correlation function solvers, and a
halo module that covers mass functions, linear bias, density profiles, and concentration-mass relations for cold, warm, and fuzzy dark matter scenarios. All core routines are validated against the Python package colossus, hmf, and halomod, yielding sub-percent agreement for shared models across distances, power spectra, variance, correlation functions,
halo mass functions, and density profiles. Phantom is organised around a cosmology structure that stores background expansion, growth, and linear power-spectrum handles; this object is constructed once and passed through the call graph, so that
halo statistics and
halo structure calculations remain consistent by design. From this single entry point, users can obtain field statistics (power spectrum, variance, correlation function),
halo statistics (mass functions, linear bias), and
halo observables (enclosed mass, circular velocity, projected density, and
lensing convergence) on arbitrary user-defined grids. The toolbox targets users whose analysis pipelines are written in MATLAB or Octave, where a validated native implementation of these models has been absent. The code is released under the MIT licence at phantom(https://github.com/matc-thaher/PHANTOM).
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