Quantum Physics
Electron decoherence in cylindrical holes and circular apertures
Cruz I. Velasco and F. Javier García de Abajo
The coherence of free electrons sets fundamental limits on the resolution and contrast of phase-sensitive electron microscopy because coherence is lost whenever the electron leaves a distinguishing excitation in its environment. We develop a quantitative theory of fast-electron decoherence in two canonical geometries: a cylindrical hole drilled through a realistic metal and a circular aperture in a thin perfectly conducting film. By combining an electromagnetic Green-tensor formulation with the fluctuation–dissipation
theorem while fully retaining retardation, we obtain the decoherence probability and elastic phase as functions of the electron trajectory, temperature, and material response. For the cylindrical hole, we obtain a closed-form, azimuthally resolved expression that separates the dependences on path position, temperature, and conductivity. In the high-conductivity and high-temperature limits, this result reduces to a universal expression that is linear in temperature and independent of both conductivity and electron velocity. For the circular aperture, which we solve using a cylindrical-wave modal expansion, the energy-loss probability diverges as $1/\omega$ at low frequency, whereas the decoherence probability remains finite and reaches a maximum when the aperture radius is comparable to the relevant electromagnetic wavelength. Because the interaction is spatially localized, aperture-induced decoherence is generally weaker than that produced by a cylindrical hole, except for sufficiently large apertures at high temperature. Finally, we show that, for sufficiently large holes, decoherence can dominate the spatial broadening of a focused electron probe and must therefore be incorporated into the design of coherent electron-beam instruments.
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High Energy Physics (Theory)
Knizhnik-Zamolodchikov equations and the analytic structure of strings in AdS$_3$
Sergio Iguri, Nicolas Kovensky and Julian H. Toro
The pole structure of string correlators in AdS$_3$ encodes essential information about the AdS$_3$/CFT$_2$ duality. The corresponding residues for spectrally flowed three-point functions have been extracted from their exact expressions and shown to match the predictions of the
holographic CFT. Away from the tensionless point, the latter is defined perturbatively in terms of a deformed symmetric orbifold. For $n$-point functions, this has so far only been achieved for a specific subset of poles and employing free-field techniques. Here we develop an alternative approach. We show that, starting from the localization properties of worldsheet correlators, one can solve the KZ equations on the corresponding locus and perform the integration over worldsheet
moduli explicitly for any $n$ and for arbitrary values of the spectral flow charges. This provides a systematic framework for computing the remaining residues and, ultimately, for determining the full analytic structure of string amplitudes in AdS$_3$.
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Instrumentation and Methods for Astrophysics
Refactoring the SIXTE simulator: Towards a more modular code base
Christian Kirsch, Maximilian Lorenz, Lea Dauner et al. (+7 more)
The SIXTE (SImulation of X-ray
TElescopes) software is a general end-to-end simulation toolkit for X-ray observations, covering the full observation process from source
photon generation to detector readout and the production of high-level output files. It is the official simulator for existing and future X-ray missions, such as eROSITA, NewAthena, THESEUS and AXIS. Originally being designed as a simulator for eROSITA, the addition of new instrument and
telescope types over several years has made the original code base increasingly difficult to maintain. As such, we have refactored the code, changing
languages from C to C++ and switching to a more modular software design to facilitate the implementation of new models. This proceeding highlights some of the design choices used during the refactoring as well as its effects on maintenance and new feature development one year after release of the refactored code base.
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All authors Christian Kirsch, Maximilian Lorenz, Lea Dauner, Esin G. Gülbahar, Karan Pal, Neo Reinmann, Jakob Stierhof, Philipp Thalhammer, Thomas Dauser, Jörn Wilms
Mesoscale and Nanoscale Physics
Dynamical transition in non-Hermitian Chern insulator
Zhi-Qiang Zhang, Yuan-Hang Ren, Ming Lu et al. (+1 more)
We unveil a peculiar dynamical transition for the propagation of wave packets in non-Hermitian Chern
insulators, where the
evolution of the topological wave packets at the edge is not solely determined by the topological Chern number. Unlike the Hermitian Chern
insulator, where a wave packet initiated at the edge propagates along the system boundary, here it may instead penetrate into the bulk. This behavior is attributed to the competition between the localization induced by conventional
topology and the non-Hermitian skin effect. Specifically, when the former dominant, the wave packet will evolve along the boundary; otherwise, it will spread into the bulk. These features demonstrate that while the generalized-Brillouin zone framework reliably predicts topological phase transitions, it does not on its own specify the dynamical transitions.
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All authors Zhi-Qiang Zhang, Yuan-Hang Ren, Ming Lu, Hua Jiang
Quantum Physics
Seungcheol Oh, Chaemoon Im, Daeyeun Kim et al. (+4 more)
The output of a parameterized
quantum circuit (PQC) can be expressed as a finite
Fourier series whose accessible frequencies are fixed by the data-encoding gates. While the encoder determines which frequencies can appear, the corresponding
Fourier coefficients depend on how the trainable and entangling gates are arranged. Although existing studies provide metrics for characterizing how gate structure affects
Fourier coefficients, they do not translate these analyses into an explicit design criterion specifying how gates should be arranged to make a target coefficient reachable. In this paper, we provide such a criterion. Using the adjoint action of the encoding generator, we decompose operator space into two-dimensional invariant planes indexed by frequency and show that each
Fourier coefficient is exactly a sum of bilinear projections of the effective state and observable onto the planes at that frequency. Because, for Pauli encodings, high-frequency planes are spanned by mixed multi-
qubit Pauli strings, a target coefficient can contribute to the output only when local rotations and entangling layers are arranged so that both the effective state and observable acquire support on one of its planes. For Pauli readouts and commuting two-
qubit entanglers, this yields a
circuit design rule that specifies, for a given interaction graph, a placement of local rotations and entangling layers that makes a target
Fourier coefficient reachable. Using a single encoding layer, we validate the proposed design through a placement ablation, regression tasks from PDEBench and physics-informed Maxwell field modeling, and further demonstrate its robustness to moderate simulated gate noise and damping.
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All authors Seungcheol Oh, Chaemoon Im, Daeyeun Kim, Soohyun Park, Vaneet Aggarwal, Mohsen Heidari, Joongheon Kim
Quantum Physics
Temporal trade-offs in high-dimensional entanglement: a comprehensive noise model for optimal time-bin QKD protocols
Alexandra E. Bergmayr-Mann, Gláucia Murta and Marcus Huber
High-dimensional time-bin
entanglement is known for having high potential for
quantum key distribution (QKD) applications, being easily implementable, robust and may offer better keyrates than simple
qubit protocols. The temporal encoding, combined with limited clock resolution, however, implies a trade-off: Is it better to send more low-dimensionally encoded
photons or few high-dimensional ones? Answering this question presents a hard challenge as it depends on the entire context of the protocol, including the production rates, losses, dark counts, timing jitters and many more. We answer this question for single Franson based interferometers and asymptotic key rate and shared
entanglement as main figures of merit. We present a flexible noise model incorporating all relevant parameters and find that there are indeed regions where high-dimensional encoding still outperforms any
qubit based version when the pair arrival rate is limited, for instance through loss or limited pump power.
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Statistical Mechanics
Out-of-equilibrium finite-time percolation transitions and spinodal-like behaviors after quenches across magnetic first-order transitions of Ising systems
Andrea Pelissetto, Davide Rossini and Ettore Vicari
We analyze the out-of-
equilibrium relaxational dynamics of
ferromagnetic Ising-like systems driven across their low-temperature
magnetic first-order transition (FOT) line, by sudden and slow variations of an external homogenous
magnetic field $h$. As a paradigmatic example, we consider a two-dimensional Ising system driven across its low-temperature FOT line by suddently quenching $h$ from $h_i<0$ to $h>0$, inducing a transition from the negatively to the positively magnetized phase. We show the emergence of a dynamic percolation transition at a finite critical time $t_c(h)$ along the post-quench
evolution for finite (sufficiently small) values of $h$, which is marked by the percolation of the largest positive-
spin cluster and the antipercolation of the largest negative-
spin cluster. This out-of-
equilibrium percolation transition displays a finite-size scaling behavior as in the standard random-percolation case. However, while the fractal dimension of the percolating clusters is consistent with the random-percolation value, the exponent controlling the approach to criticality differs and depends on $h$. We also show that the percolation transition marks the passage from the metastable negatively-magnetized phase to the stable positively-magnetized one. Therefore, in the small-$h$ limit, the percolation critical behavior is related to the spinodal-like behavior of the magnetization, implying that the percolation time $t_c(h)$ exhibits a spinodal-like exponential dependence on $h$. The existence of percolation transitions is likely a generic phenomenon at
magnetic Ising-like FOTs. For example, we observe an analogous behavior in dynamic (Kibble-Zurek-like) protocols entailing slow variations of the
magnetic field driving the crossing of the FOT line.
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Quantum Physics
Improving the Stability of the Hierarchical Equations of Motion for Open Quantum Systems with Strong Coupling to Structured Bosonic Baths
Salvatore Gatto, Samuel L. Rudge, Bokang Hou et al. (+2 more)
The hierarchical equations of motion (HEOM) approach is one of the most powerful methods avail- able to simulate the dynamics of open
quantum systems. Although the HEOM approach has been shown to be stable and efficient in many parameter regimes and physical scenarios, it is also well known that the unavoidable finite truncation of the hierarchy can lead to fundamental numeri- cal instabilities for bosonic environments. In this work, we apply recently developed techniques to analyze these issues. We use an auxiliary Fock-space picture of the hierarchy to first identify the unbalanced hierarchy-raising terms responsible for the strong transient amplification associated with the non-normal algebraic structure of the HEOM generator. We then apply a non-
unitary similarity transformation that converts these terms into balanced combinations of hierarchy-raising and hierarchy-lowering terms, thereby suppressing their numerical impact. We first demonstrate the efficacy of this approach via a
spin-
boson model with a simple Brownian oscillator spectral den- sity and subsequently extend the analysis to a structured spectral density, showing for both cases that the transformed HEOM approach allows simulations of much larger system-bath coupling than would otherwise be possible.
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All authors Salvatore Gatto, Samuel L. Rudge, Bokang Hou, Eran Rabani, Michael Thoss
Mesoscale and Nanoscale Physics
Extracting the anyonic exchange phase from co-tunneling through an open quantum dot
Felix Puster, Matthias Thamm and Bernd Rosenow
The elementary excitations of fractional
quantum Hall states obey anyonic statistics, described by an exchange phase $\theta$ intermediate between the bosonic and fermionic values. We study an interferometer in which three
chiral edge segments are pairwise connected by three
quantum point contacts, so that, depending on the applied voltages, one of the segments acts as an open
quantum dot: its spectrum is continuous, and tunneling through it is resonant without any gate tuning. This setup realizes the co-tunneling mechanism of a recently proposed antidot interferometer in a particularly simple setting. Using a non-
equilibrium Keldysh calculation to third order in the tunneling amplitudes, we show that the interference current contains a co-tunneling contribution in which two quasiparticles are exchanged, so that for Laughlin states the exchange phase $\theta=\pi\nu$ appears as the phase shift between the Aharonov-Bohm oscillations measured in two voltage configurations. We obtain a closed analytic expression for the interference current at finite temperature and finite separation between the
quantum point contacts and show that, provided voltage-induced changes of the enclosed area are sufficiently screened, the exchange phase can be extracted from a robust phase-plateau difference. Alternatively, simultaneous measurements of the interference currents at two drains avoid this screening assumption and time-of-flight phases can be quantified analytically, allowing the exchange phase to be extracted by a controlled extrapolation with a few-percent systematic error.
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Optics
Plasmon-Enhanced Second-Harmonic Generation in Atomically Thin Crystalline Silver Nanostructures
Saad Abdullah, Philipp K. Jenke, Andrew P. Weber et al. (+8 more)
The intrinsically weak nonlinear optical response of existing materials, further constrained by
symmetry-forbidden second-order processes in centrosymmetric media, severely limits efficient frequency conversion in deeply subwavelength, ultrathin volumes. Addressing this challenge is crucial for the development of nonlinear nanophotonics. Here, we show that atomically thin, epitaxially grown crystalline silver films circumvent these restrictions through the interplay of vertical electronic
quantum confinement and lateral plasmonic enhancement. We fabricate atomically thin films that exhibit an enhanced nonlinear response associated with electronic
quantum wells, and subsequently pattern them into periodic nanoribbon and nanotriangle arrays sustaining infrared localized surface plasmon resonances. Strong near-field confinement in these structures further boosts second-harmonic generation compared to unpatterned films. Precise control over nanostructure geometry enables spectral tuning of the plasmonic resonance, and consequently, the enhanced harmonic frequency. Our findings establish an approach for activating robust second-order nonlinearities in
quantum-confined metals, where intrinsic size effects and plasmonic resonances act synergistically. The compatibility of high-quality epitaxial growth with microchip fabrication technology offers a scalable route toward ultracompact nonlinear optical components for on-chip frequency conversion, sensing, and
quantum photonic applications.
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All authors Saad Abdullah, Philipp K. Jenke, Andrew P. Weber, Álvaro Rodríguez Echarri, Vahagn Mkhitaryan, Fadil Iyikanat, Frederik Schiller, Philip Walther, J. Enrique Ortega, Lee A. Rozema, F. Javier García de Abajo
Astrophysics of Galaxies
Diverse Metallicities in Protoclusters at $z \sim 3.4$ detected by Deep Learning
Yoshihiro Takeda, Nobunari Kashikawa, Kei Ito et al. (+12 more)
We present spectroscopic follow-up observations with Subaru/MOIRCS of four protocluster candidate regions identified by the deep-learning model PCFNet. In three candidate regions, we confirm four protoclusters at $z =$ 3.316, 3.403, 3.408 and 3.425, exhibiting
galaxy density peaks over five times the uniform distribution. The detection rate of confirmed members aligns with PCFNet's predictions, underscoring its effectiveness. Analysis of spectral energy distributions (SEDs), incorporating up to ten photometric bands $(uu^*grizyJHK)$, reveals that protocluster members lie on the
star-formation main sequence. The masses of the most massive
halos in the protoclusters are estimated from the most massive
stellar mass of the member
galaxies, yielding $\log M_\mathrm{halo}/M_\odot=12.4$-$12.8$, which are consistent with those at this
redshift predicted by cosmological simulations and are comparable to those of the progenitors of typical local clusters ($M_\mathrm{halo}^{z=0}\sim10^{14}M_\odot$). Using the Voronoi Tessellation Monte Carlo technique based on the probability of protocluster membership from PCFNet, we find that our protoclusters exhibit a significantly higher SFRD than the
cosmic SFRD at $z\sim3.4$. Based on the [Oiii]/H$\beta$ emission line ratio, two protoclusters show marginally ($1.4$-$2\sigma$) higher average
metallicities than the field, while the other protoclusters are statistically consistent with the field. These diverse
metallicities highlight the environmental impact within protoclusters detected by PCFNet, likely reflecting the complex opposing interplay between metal-rich gas recycling and metal-poor gas inflow, which may depend on the surrounding environment of each protocluster. This work demonstrates PCFNet's capability to unveil diverse samples of high-
redshift protoclusters, paving the way for a more comprehensive understanding of their role in
galaxy evolution.
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All authors Yoshihiro Takeda, Nobunari Kashikawa, Kei Ito, Jun Toshikawa, Mariko Kubo, Rieko Momose, Yongming Liang, Takehiro Yoshioka, Junya Arita, Hiroki Hoshi, Shunta Shimizu, Hisakazu Uchiyama, Satoshi Kikuta, Ryo Emori, Kentaro Koretomo
High Energy Physics (Phenomenology)
Exploring $U_A(1)$ symmetry restoration in a magnetic field by meson screening masses in the NJL model
Bing-Kai Sheng, Zigeng Ding, Danning Li et al. (+2 more)
We investigate the effective axial $U_A(1)$
symmetry restoration at finite temperature in an external
magnetic field using
meson screening masses, as well as
meson susceptibilities, in a $(2+1)$-
flavor Nambu-Jona-Lasinio (NJL) model. To incorporate inverse
magnetic catalysis, we employ a
magnetic-field-dependent four-
quark coupling constrained by the
lattice QCD
chiral pseudo-critical temperature, with the 't Hooft coupling fixed. In the
lattice-improved NJL model, the longitudinal screening mass difference between the $U_A(1)$ partners $\delta^0$ and $\pi^0$ and their normalized
meson susceptibility difference exhibit axial
magnetic catalysis at low temperatures and axial inverse
magnetic catalysis near the
chiral crossover, whereas the transverse screening mass difference increases with $eB$ at all temperatures. Despite these different responses, the axial pseudo-critical temperatures extracted from the thermal inflection points of these three alternative order parameters decrease with $eB$, implying that a decreasing pseudo-critical temperature can coexist with an increasing transverse screening mass difference at fixed temperature.
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All authors Bing-Kai Sheng, Zigeng Ding, Danning Li, Xinyang Wang, Lang Yu
High Energy Physics (Phenomenology)
Differential Higgs production at small-$x$
Benedetta Bernardini
In the context of precision physics, the resummation of large logarithms of the variable $x = Q^2/s$ is increasingly relevant at high energies. We report here preliminary results on the extension of the differential resummation formalism within the HELL framework to
Higgs boson production via
gluon fusion.
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High Energy Physics (Theory)
Regge in Wonderland
Alessio Miscioscia, Dmitrii Pavshinkin and Fedor K. Popov
We study the asymptotic behavior of large-
spin operators in conformal field theories by placing the theory on a pp-wave background. In this setting, three-point coefficients involving two large-
spin operators and a light operator are mapped to thermal one-point functions on the pp-wave. We predict these one-point functions in the two complementary regimes of high- and low-temperature respectively, corresponding to a limit in which the twist scales with an appropriate power of the
spin and the
spin is parametrically larger than the twist, respectively. In particular, at high temperature we derive their asymptotic behavior using thermal effective field theory while at low temperature we obtain results that can be matched directly to predictions from the analytic bootstrap. We test these general results in free scalar theories. Finally, we solve the large-$N$ $\mathrm{O}(N)$ model numerically on the pp-wave, finding agreement with our predictions for both the one-point function and the free energy in the high- and low-temperature regimes.
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High Energy Physics (Theory)
A gravitational realization of Courant–Hilbert deformations
Osamu Fukushima, Miyabi Kurihara, Takaki Matsumoto et al. (+1 more)
Courant–
Hilbert (CH) deformations unify broad classes of solvable stress-tensor flows including $T\bar{T}$ and root-$T\bar{T}$. However, a gravitational action that systematically yields such general deformations has remained unknown. In this Letter, we construct a two-dimensional massive
gravity theory whose on-shell action reproduces the complete CH deformation. The
gravity sector is defined via an arbitrary function of the
eigenvalue ratio $y$ of the relative zweibein. To bypass the technical difficulty of directly eliminating the auxiliary zweibein, we reformulate the matter sector using a $2 \times 2$ spectral decomposition involving $y$ and a rank-one projector $K$. Sequentially solving the equations of motion—first for $K$ and subsequently for $y$—naturally maps the system onto the Russo-Townsend form of the CH flow. Our work extends Tolley's massive
gravity formulation of $T\bar{T}$ flows to the CH landscape, providing a clear
geometric mechanism for solvable stress-tensor flows.
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All authors Osamu Fukushima, Miyabi Kurihara, Takaki Matsumoto, Kentaroh Yoshida
Quantum Physics
Efficient classical algorithm for estimating linear statistics of Boson Sampling
Benoit Seron, Hugo Thomas, Eduardo Araujo et al. (+3 more)
Boson Sampling is a prominent candidate for the demonstration of
quantum computational advantage but it remains unclear whether a large-scale
boson sampler can find useful computational applications. The challenge is that to use a
boson sampler to estimate, for example, a physical observable, it is necessary to coarse grain the outcome distribution, owing to the exponential size of the outcome space and the anti-concentration properties of the
Boson Sampling distribution. In this work, we analyse the complexity of a specific type of coarse-graining of
Boson Sampling distributions based on linear functions of the output
photon occupation numbers, which we refer to as linear statistics. We present an efficient classical
algorithm for approximating linear statistics of
boson samplers within additive error for different kinds of input states, such as Fock states and squeezed states. This allows us to unify in the same framework recent results on efficient
quantum-inspired classical
algorithms for simulating molecular vibronic spectra, or efficient classical approximations of coarse-grained distributions based on detector binning. Additionally, we show how our
algorithm can be used to classically evaluate a proposed one-way function based on
Boson Sampling, while other proposals for cryptographic applications escape our classical simulation techniques. We leave open the question of classical simulability of non-linear statistics and connect it to the problem of computing transition amplitudes of linear-optical
circuits with one layer of interactions.
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All authors Benoit Seron, Hugo Thomas, Eduardo Araujo, Alex Arkhipov, Changhun Oh, Leonardo Novo
Quantum Physics
Fixed-Time Gaussian State Transfer via Collective Dissipation in a Fully Static Architecture
Austen Couvertier and Ting Yu
We establish a fully static, dissipation-only primitive for Gaussian state transfer in which collective coupling to a shared environment fixes a single transfer time without coherent transport or time-dependent control. The dynamics close in a bright–dark decomposition, yielding an analytic transfer time $t^{*} = \pi / g_{a}$ and a real interference factor that eliminates dynamical phase accumulation, so that all phase sensitivity arises solely from the Gaussian fidelity metric. This defines a fixed-time Gaussian communication channel in which dissipation mediates information transfer without active control. Ensemble analysis shows that channel performance remains robust to amplitude-level asymmetries, which act as uniform-rate dressing, whereas phase-level system detuning disrupts the fixed-time mechanism via dynamical phase winding and produces revival behavior. Incorporating finite Ornstein–Uhlenbeck
memory via a zeroth-order O-operator expansion yields only rate and phase renormalization without introducing new dynamical pathways. In the fast-
memory regime, environmental correlations are rapidly suppressed, rendering the channel insensitive to environmental detuning and restoring the Markovian limit. These results show that collective dissipation alone is sufficient to support fixed-time Gaussian state transfer, challenging the assumption that coherent transport or active control are required for continuous-variable communication.
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Mathematical Physics · Cross-listed from math.CA
Toward Pólya and Szegő's conjecture for logarithmic vs Newtonian capacity
Carrie Clark and Richard S. Laugesen
Pólya and Szegő conjectured in 1945 that the disk achieves the largest electrostatic capacity among all planar sets with given logarithmic capacity. This question generalizes naturally to balls and Newtonian capacities in higher dimensions. The
conjecture remains open. This paper establishes a conditional result: the
conjecture would follow if among all lower dimensional sets in a horizontal strip with Neumann boundary conditions, the transverse component of the Dirichlet integral of the
equilibrium potential could be shown minimal for the lower dimensional ball. As supporting evidence toward this latter property, the paper shows extremality of the ball for $L^p$-norms of the potentials, via Baernstein
star-function symmetrization techniques.
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Atmospheric and Oceanic Physics
A Reduced-Order Coupled Oscillator Model for the Emergence of Episodic Convection
Sooman Han, Soong-Ki Kim, Bowen Fan et al. (+3 more)
Extreme precipitation is a societal concern, and understanding tropical moist convection is increasingly important in a warming
climate.
Climate simulations show that, under hothouse Earth, convection can transition from quasi-steady precipitation to an episodic regime characterized by intense rainfall bursts separated by dry intervals, although the mechanisms governing this transition remain debated. Here we develop a reduced-order framework that represents tropical convection through column-integrated moisture (q) and thermal stratification (Delta), rather than bulk measures of convective instability. Analysis of cloud-resolving model (CRM) simulations shows that these variables evolve together: during dry periods, surface fluxes recharge moisture, while radiative and dynamical processes erode stratification generated by previous convection. We couple this
evolution to the nonlinear moisture dependence of tropical precipitation (P), whereby rainfall increases sharply above a critical moisture threshold. A third prognostic variable, C, represents convective persistence, allowing convection to continue below its onset threshold and thereby producing hysteresis. With parameters constrained by CRM output, the model reproduces the
evolution of q, Delta, and P in both regimes, representing quasi-steady convection as stable, noise-driven oscillations and episodic convection as an unstable, self-sustained limit cycle. Linear stability analysis shows that the transition depends on moisture-recharge and stratification-adjustment timescales, thermal-moisture sensitivity, and convective persistence. Because radiative and dynamical processes enter through their effects on thermal stratification, the framework is not tied to a specific mechanism, providing a unified dynamical link between moisture-threshold precipitation behavior and the emergence of episodic convection under warming.
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All authors Sooman Han, Soong-Ki Kim, Bowen Fan, Jérôme Vialard, Alexey V. Fedorov, Juan M. Lora
Instrumentation and Methods for Astrophysics
Source–Line Associations in JWST/NIRSpec Dense-Shutter Spectroscopy
Zihao Wu, Daniel J. Eisenstein, Francesco D'Eugenio et al. (+9 more)
We demonstrate the feasibility of source–line association in JWST/NIRSpec dense-shutter spectroscopy, with $\sim$2000 sources observed simultaneously per pointing regardless of spectral overlap. While JWST wide-field slitless spectroscopy (WFSS) can disentangle overlapping spectra using two grisms with perpendicular dispersion directions, NIRSpec can achieve this using gratings with different dispersions. Compared with WFSS, NIRSpec dense-shutter spectroscopy offers substantially higher sensitivity and broader wavelength coverage. We develop a
Bayesian framework that combines cross-dispersion offsets, wavelength consistency, and changes in relative line positions between gratings to jointly determine source associations and
redshifts. We test the method using mock observations based on the observed source distribution and emission-line fluxes from the JWST Advanced Deep Extragalactic Survey (JADES), accounting for the NIRSpec optical model, MSA operability, measurement noise, false-positive detections, and bad pixels. Although the spectral traces overlap extensively, fewer than 0.5% of the simulated emission lines are blended with another line on the detectors in NIRSpec grating spectroscopy. Applying our method to these simulations, we obtain
redshifts, at an accuracy of 98%, for the $\sim$1800 sources that have detectable emission lines, of which $\sim$1500 are classified as confident and are 99.9% accurate. We further investigate how the association accuracy depends on the number of grating configurations. By combining high multiplexing, high sensitivity, and broad wavelength coverage, NIRSpec dense-shutter spectroscopy enables efficient, highly complete spectroscopic surveys for the high-
redshift Universe.
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All authors Zihao Wu, Daniel J. Eisenstein, Francesco D'Eugenio, Erica Nelson, Benjamin D. Johnson, Andrew J. Bunker, Zhiyuan Ji, Pierluigi Rinaldi, Brant Robertson, Sandro Tacchella, Christopher N. A. Willmer, Joris Witstok
Solar and Stellar Astrophysics
V405 Draconis: A Deep Contact Binary with a Tertiary Companion and a Quadruple System Candidate
Maksym Yu. Pyatnytskyy and Ivan L. Andronov
We continued our analysis of the O-C diagram of the EW-type eclipsing binary V405 Dra using recently available data. We refined the orbital parameters of the third body responsible for the short-period oscillations in the O-C curve, obtaining $P_3=513.12(20)$ d, $a_{12}\sin i_3=0.3862(15)$ AU, and $e_3=0.1690(48)$. Assuming a total mass of $1.56$ $M_\odot$ for the eclipsing binary, the minimum mass of the third body is estimated to be about $0.5$ $M_\odot$. We also investigated the complex long-term O-C trend and found that it may be partially explained by the light-time effect caused by a possible fourth body, with a characteristic period of about 23.5 yr and a minimum mass of about $0.9$ $M_\odot$. However, the fourth-body model cannot fully reproduce the observed long-term variation, particularly the earliest data, and the nature of part of the long-term trend remains unexplained.
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Physics and Society
A citizen science behavioural dataset of an urban collective-risk dilemma on air pollution mitigation under resource inequality
Marc Sadurní, Martín F. Díaz, Julián Vicens et al. (+4 more)
This article describes a behavioural
dataset from a collective-risk dilemma public experiment carried out in Barcelona, Spain, within the citizen science xAire air quality project. Participants played a ten-round game in groups of six, each deciding every round how many monetary units to contribute from a private endowment toward a shared target; groups that fell short forfeited all remaining capital. Three endowment treatments held the group total fixed: an equal condition and two unequal conditions in which low-endowment participants formed either the minority or the majority of the group. Data were collected at two public outdoor venues using a tablet-based interface under lab-in-the-field protocols. Participants were recruited on-site from a demographically heterogeneous pool of individuals passing through the venues, mostly local residents. The
dataset comprises 462 participants across 77 six-player games, 4\,620 contribution decisions in total. Each participant record links the full ten-round contribution trajectory to initial endowment, wealth treatment, venue, district of residence and its measured nitrogen-dioxide concentration, and socio-demographic and attitudinal survey items covering gender, age, education, economic and working status, air-quality perception,
fairness norms, environmental-justice beliefs, residential mobility, and community participation. The release provides raw and cleaned participant tables, a variable codebook, the survey instrument, the district-pollution linkage, and the preprocessing code.
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All authors Marc Sadurní, Martín F. Díaz, Julián Vicens, Anna Cigarini, Isabelle Bonhoure, Miquel Montero, Josep Perelló
Quantum Physics
Jonáš Fuksa, Clara Wassner, Jens Eisert et al. (+1 more)
Connecting mathematical formalism in open
quantum systems to its underlying physics necessitates the notion of a dilation, a way to bridge
stochastic dynamics with deterministic Schrödinger
evolution on a larger space. Although dilations are well known in the literature for states, channels, and
quantum combs, there is a substantial gap when it comes to the fully general setting of non-Markovian dynamics on a continuous interval. In an accompanying work, we introduce a continuous process tensor (cPT) framework wherein these processes are represented by vectors in multi-species bosonic Fock spaces of $L^2$ functions. This accommodates all multi-time statistics of a
quantum system on an interval. Here, we present a corresponding dilation
theorem and show that all cPTs can be approximated arbitrarily well by an explicit closed description with system and environment coupled by a bounded
Hamiltonian. As well as its physical appeal and demonstrating completeness of the framework, we show that such regular representations actually underpin the formalism, defining a dense subspace of all cPTs that is easy to handle. This leads to a continuum-suitable version of Choi duality, and permits the rigorous treatment of continuum controls.
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All authors Jonáš Fuksa, Clara Wassner, Jens Eisert, Gregory A. L. White
Atomic Physics
Qprop-ND: A Nondipole Extension of the Qprop Package for Strong-Field Laser Physics
Haoyuan He, Zhao-Han Zhang, Karen Z. Hatsagortsyan et al. (+1 more)
The Qprop 3.0 package for the solution of the time-dependent Schrödinger equation for an electron in a
laser field and atomic potential is extended to incorporate nondipole effects related to the
laser wave propagation. The developed code can be used for the simulation of strong field atomic phenomena in the nondipole regime, such as above-threshold ionization, ionization stabilization in high-frequency
laser fields, high-order harmonic generation, when the effects connected with the
magnetic field are non-negligible or when the
laser wavelength is comparable with the atomic size. Similar to the dipole Qprop the wave function is expanded in spherical harmonics, the time-propagation of the wave functions is performed using the Crank- Nicolson approach, and the photoelectron spectra are calculated employing the t-SURFF or i- SURFV methods. The validity and accuracy of the implementation are demonstrated through several illustrative examples.
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All authors Haoyuan He, Zhao-Han Zhang, Karen Z. Hatsagortsyan, Christoph H. KeiteL
Geophysics · Cross-listed from cs.AI
Structural Alignment for Reliable Industrial AI: Bridging Physical Reality, Data, Models, and Human Intent
Lizhi Xiao, Sihong Wu, Victoria Xiao et al. (+5 more)
Artificial intelligence is increasingly deployed in critical industrial domains, including healthcare, energy grids, subsurface exploration, where failures can have severe consequences for human safety, system stability, and economic outcomes. Yet AI is still evaluated primarily through
benchmark accuracy, a model-centric metric that fails to capture the structural complexity and risks of real-world deployment. We propose a framework that views industrial AI reliability as a problem of structural
alignment across four interacting worlds: physical, representational, machine, and human cognitive. These worlds are connected through two interfaces: digitalization, linking physical reality to computational representations, and goal encoding, translating human cognition to the machine objectives. Together, they define the space of admissible solutions. We characterize the solution space through four attributes: existence, non-uniqueness, robustness, and interpretability and show how mismatches arise at interfaces and propagate across worlds to produce reliability failures. Applications to healthcare, energy grids, and subsurface exploration illustrate that although dominant failure modes differ across domains, for example, interpretability in healthcare, robustness in energy grids, and non-uniqueness in subsurface exploration, all originate from a shared structural mechanism. By shifting the focus from model-centric evaluation to system-level
alignment, this framework offers a principled foundation for assessing and governing reliability in industrial AI systems.
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All authors Lizhi Xiao, Sihong Wu, Victoria Xiao, Yiqiao Song, Chen Gu, Jianwei Ma, Xinming Wu, Aimé Fournier
Quantum Physics
Heuristic lower bounds on real Grothendieck constants of finite and infinite order
Erika Bene and Tamás Vértesi
We propose candidate lower bounds on the real Grothendieck constants $K_{\mathrm G}(d)$ and their infinite-dimensional limit $K_{\mathrm G}$ using rotationally invariant cubic kernels. For the continuous construction, we identify an explicit threshold above which hemispherical binary strategies are unstable under cubic boundary deformations. Supported by numerical evidence, we
conjecture that hemispherical strategies are globally optimal at this threshold. This
conjecture would imply $K_{\mathrm G}\geq9\pi/16\simeq1.767146$, improving the rigorous lower bound $6\pi/11\simeq1.713596$. We also construct finite symmetric coefficient
matrices from unit vectors in dimensions up to $24$. Large-scale see-saw optimization supports the continuous predictions and suggests improved lower bounds on $K_{\mathrm G}(d)$ in the studied dimensions from $4$ to $24$, conditional on the conjectured binary optima being exact. Selected
matrices also yield finite-setting candidate dimension witnesses when interpreted as bipartite correlation Bell functionals. If the corresponding binary upper bounds hold, these witnesses would certify a local
Hilbert-space dimension of at least five for each party.
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Instrumentation and Detectors
A linear Paul trap to study the equilibrium of charged micron-sized particles in air
Roxen Wilby Kissangou, Marius Romuald Kamsap, Mike Delon Mboumba et al. (+2 more)
We describe and use a macroscopic linear quadrupolar trap to explore the trapping and
equilibrium properties of charged particles. These devices, when operated to trap atomic ions, are at the core of ion based
quantum computer and optical atomic clock. To illustrate the characteristics of few particle trapping, and observe different force balance on a charged particle, a macroscopic linear trap, operating at room condition, is trapping micrometer-sized particles. Compared to atomic or molecular ions, their mass can not be neglected and requires an extra voltage for
gravity force compensation. We show how this compensation can be demonstrated experimentally and that the choice of hollow-core glass spheres has the advantage of a good reproducibility of the experiments, that allows one to deduce with good precision the charge-to-mass ratio of the trapped particle.
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All authors Roxen Wilby Kissangou, Marius Romuald Kamsap, Mike Delon Mboumba, Marie Houssin, Caroline Champenois
Mathematical Physics · Cross-listed from math.PR
Infinite-Particle Determinantal Dynamics from Brownian Motion on $\mathrm{GL}_N(\mathbb{C})$
Zahra Sadat Mirsajjadi
We study the edge scaling limit of the logarithms of the squared singular values of multiplicative Brownian motion on the general linear group $\mathrm{GL}_N(\mathbb{C})$ with general initial conditions. Building on earlier work [arXiv:2605.06429], we prove that, for every initial condition in the enhanced state space, the limiting dynamics are determinantal and derive an explicit double-contour formula for their extended multitime correlation kernel. The dependence on the initial state, including information not determined by the particle coordinates, is encoded by the associated Laguerre–Pólya entire function. We further extend the corresponding infinite-dimensional
stochastic differential equation description to arbitrary initial configurations, including those with coinciding coordinates.
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Materials Science
Pressure-induced s,p-d electron redistribution accompanies structural transformation in amorphous Zr-Cu alloy under compression
P. Dziegielewski, J. Antonowicz, K. Georgarakis et al. (+6 more)
Extreme compression can reorganize atomic valence states, in some regimes driving charge from spatially extended orbitals into more compact ones. We investigate this effect in amorphous Zr67Cu33 metallic glass by combining high-pressure X-ray absorption fine structure measurements up to 69 GPa with molecular dynamics simulations and density functional theory calculations. The Zr K-edge XANES spectra show a pronounced increase in the pre-edge intensity and a change in its pressure dependence, whereas the Cu response is markedly weaker. Molecular-dynamics simulations reproduce the measured EXAFS spectra and provide reliable input for the electronic-structure calculations. The calculated Mulliken populations reveal pressure-induced depletion of Zr s and p-states, accompanied by an increase of the d-state population, while the density of states indicates enhanced p-d hybridization under compression. These results provide experimental and computational evidence for pressure-induced s,p-d electronic redistribution in zirconium and link this effect to the previously reported anomalous structural
evolution of the compressed amorphous
alloy.
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All authors P. Dziegielewski, J. Antonowicz, K. Georgarakis, O. Lord, M. Amboage, D. Daisenberger, L. Clough, T. Irifune, T. Shinmei
Disordered Systems and Neural Networks · Cross-listed from cs.LG
First Learn, Then Memorize: The Spectral Bias of Diffusion Models
Raphaël Urfin, Tony Bonnaire, Giulio Biroli et al. (+1 more)
Diffusion models trained on a finite
dataset first learn to generate novel, high-quality samples and only much later collapse onto their training set. We identify the mechanism behind this separation of timescales and the object that probes it. The training dynamics of the score function are governed—exactly, and at any width—by the Gram
matrix of the Neural Tangent Kernel (NTK) evaluated on the noisy training data, so the timescales of generalization and of memorization must be encoded in its spectrum. We show that they are, and that the structure responsible has no analogue in standard kernel settings. The use of multiple noise realizations per sample ($m$ noised copies at a fixed noise level) in the score-matching loss is what restructures the Gram
matrix spectrum into two distinct parts. The first, of large
eigenvalues, carries the global features of the target distribution and is present already for $m=1$. The second, which the repeated noising creates, consists of the smallest
eigenvalues and is supported on eigenvectors aligned with the sample-specific noise directions; it sets a memorization timescale parametrically larger in the training set size $n$. We establish this picture on two fronts. Analytically, we solve the spectrum in the lazy high-dimensional limit for both linear ($n \asymp d$) and
polynomial ($n \asymp d^k$) sample complexities, and prove through a bias–variance decomposition that the first bulk minimizes the approximation error while the second drives the error associated with memorization. Empirically, we show the same two-bulk structure in Convolutional NTKs on CelebA and in finite-width U-Nets trained well beyond the lazy regime, and we make the link causal: truncating the Gram
matrix at rank $r$ tunes the generalization–memorization transition, and an $L_2$ penalty targeting the second bulk suppresses memorization in feature-learning U-Nets.
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All authors Raphaël Urfin, Tony Bonnaire, Giulio Biroli, Marc Mézard