Quantum Physics
State–Generator Geometry of Open Quantum Systems: Compatibility and Covariant Transport
Eric R. Bittner and Carlos Silva-Acuna
We develop a geometry for transporting stationary-state response across the control space of an open
quantum system. A physical model is represented by the ordered pair of its stationary state and dynamical generator.
Embedding these pairs in a common ambient space induces a metric, a response one-form, and a closed two-form on the control
manifold. The ambient space admits a canonical complex structure that exchanges state and generator directions, but the Liouvillian null-state condition restricts physical models to a submanifold that need not preserve this structure. For an amplitude-damped optical Bloch model, the metric and response two-form are compatible at the single point $\omega=0$ and $g/\Gamma=1/\sqrt{2}$; the physical
manifold is non-Kähler elsewhere. The induced metric defines the Levi–Civita connection, geodesics, and parallel transport without requiring Kähler compatibility. We compute the connection by automatic differentiation through the stationary Liouvillian solve and recover the symbolic result to machine precision. A two-point calculation then shows that the resulting geodesic differs from linear interpolation in control space and follows a shorter path through the family of state–generator models. This geometry supplies the intrinsic derivative and transport structure needed to carry observable response, including multidimensional spectra, between admissible stationary models.
Read the full abstract ▾
High Energy Physics (Theory)
Maximal Enhancements in Eight-Dimensional Non-Supersymmetric Heterotic Strings
Yamato Honda, Justin Kaidi, Yuichi Koga et al. (+1 more)
We classify maximally enhanced, rank-preserving non-supersymmetric heterotic strings in eight dimensions by studying orbifolds of supersymmetric heterotic strings on $T^2$. We first review the construction in nine dimensions, where it reproduces the $95$ maximally semisimple enhancement points obtained from previous extended-Dynkin analyses. We then start from the maximally enhanced supersymmetric Narain points in eight dimensions and use Kac's
theorem to enumerate candidate order-two inner actions, retaining only those that lift to consistent Narain-
lattice shifts. This gives $1210$ maximal enhancement points, of which $71$ are tachyon-free, and $25$ have neither tachyons nor shifted-sector massless scalars. For each entry we determine the gauge
algebra and the low-lying scalar and
fermion spectra, and for the tachyon-free cases we evaluate the one-loop cosmological constant. For the 25 subcases without shifted-sector massless scalars, we further compute the Hessian of the one-loop potential and test the refined de Sitter swampland
conjecture.
Read the full abstract ▾
All authors Yamato Honda, Justin Kaidi, Yuichi Koga, Yuefeng Liu
Atmospheric and Oceanic Physics
Interpretable AI predicts a 2026 summer dry anomaly in central China
Anran Wang, Wen Shi, Yong Luo et al. (+5 more)
Seasonal precipitation anomalies are largely regulated by atmospheric circulation, which dynamical models predict with greater reliability than precipitation itself. Here, we employ a deep learning model that translates dynamical circulation predictions into precipitation estimates. Predictions initialized from March to May consistently indicate a dry anomaly over central China in summer 2026. Retrospective evaluations revealed higher predictive skill in the analogue years, which also tended to feature central equatorial Pacific warming persisting from the preceding winter into summer. This warming favors an anomalous cyclonic circulation over the western North Pacific-South China Sea-South China region, which induces northerly winds and moisture divergence that jointly suppress rainfall over central China. Supporting this mechanism, layer-wise relevance propagation (LRP) independently identifies these northerly winds as the dominant driver of the prediction among all model inputs. Perturbation tests supported this attribution: removing LRP-identified features effectively eliminates the dry anomaly. Our framework thus provides physically interpretable explanations for AI-derived regional
climate projections, facilitating evidence-based assessment before observational data become available.
Read the full abstract ▾
All authors Anran Wang, Wen Shi, Yong Luo, Jianbin Huang, Lijuan Chen, Junhu Zhao, Weixin Jin, Huihui Yuan
Quantum Physics
Quantum Speedups Require Structure or Depth
Guy Blanc, Jordan Docter, Carmen Strassle et al. (+1 more)
One of the most basic
conjectures in
quantum complexity theory states that every $t$-query
quantum algorithm can be simulated on most inputs by a $\mathrm{poly}(t)$-query classical
algorithm. If true, this would provide broad justification for the need for structure in
quantum speedups. We settle this
conjecture for parallel
quantum algorithms, showing that every $t$-query $d$-round
quantum algorithm can be simulated on most inputs with $t^{O(d^2)}$ classical queries. This suggests that for unstructured problems, superpolynomial speedups would require
quantum circuits of superconstant depth, and exponential speedups would further require
polynomial depth. In contrast, most known speedups for structured problems are achieved by highly parallel, low-depth
algorithms. Our techniques also carry new implications for the status of $\mathsf{BPP}$ vs. $\mathsf{BQP}$ relative to a random oracle, a similarly longstanding problem.
Read the full abstract ▾
All authors Guy Blanc, Jordan Docter, Carmen Strassle, Li-Yang Tan
Instrumentation and Detectors
Characterisation of Commercially Available NUV-MT Silicon Photomultipliers
T. Avgitas, Z. Balmforth, I. Manthos et al. (+2 more)
Silicon Photomultipliers (SiPMs) based on NUV-MT technology offer improved photo-detection efficiency and reduced correlated noise compared to earlier designs, making them increasingly attractive for particle and astroparticle physics applications. We present a systematic characterisation of commercially available Broadcom AFBR-S4N series NUV-MT SiPMs over a wide range of temperatures and overvoltages, from -85oC to 23oC and from 10-16V overvoltage (VoV). Key performance parameters are measured, including breakdown voltage, gain, signal-to-noise ratio, dark count rate, afterpulsing probability, and both internal and external optical crosstalk. At 12Vov and 23oC a dark noise of 107.2+/-2.1 kcps/mm^2 is measured, consistent with manufacturer specifications. At 12Vov and -30oC the measurements yielded an average dark noise of 1.69+/-0.12 kcps/mm^2, an average gain of (6.88+/-0.15)x10^6, an average signal to noise ratio of 13.6+/-0.9, an average afterpulsing probability of (0.59+/-0.06)%, an average direct crosstalk probability of (26.49+/-0.28)%, an average delayed crosstalk probability of (0.72+/-0.10)%, and an average external crosstalk probability of (0.10+/-0.04)%.
Read the full abstract ▾
All authors T. Avgitas, Z. Balmforth, I. Manthos, K. Nikolopoulos, C. Toukmenidis
Astrophysics of Galaxies
Inferring the Dark from the Observable: Estimating Halo Masses Using Galaxy Properties
Alice Chen and Syeda Lammim Ahad
The formation and
evolution of
galaxies are interconnected with that of their host
halos. Given this closely related evolutionary history, it should follow that
galaxy properties are correlated with their host
halo mass. Previous works have shown that
star formation rates of
galaxies in cluster
halos differ systematically from those in field
halos, suggesting that host
halo mass plays a significant role in the history of
galaxy evolution. Here, we examine the correlations between observable
galaxy properties - such as
stellar mass,
star formation rate, half-
stellar radius, $r-$band magnitude, and color - and the underlying host
halo mass of
galaxies. Central
galaxy observables are used to probe host
halo mass, while satellite
galaxy properties are used to estimate subhalo mass. We perform this analysis using random forest, ordinary least squares (OLS), and symbolic regression. Random forest regression can assess the relative significance of different observable
galaxy properties, while OLS and symbolic regression can quantify their relationship with the host
halo mass. Our results show that gas mass is generally the most significant property in central
galaxies of all
halo mass ranges, followed by
stellar mass and observed $r-$band magnitude. Adding parameters such as the colour and magnitude of
galaxies improves host
halo mass estimations compared to standard
stellar-to-
halo mass relations. These results show that
halo mass likely has a multi-dimensional dependence on
galaxy properties and open the avenue of finding a simple way to constrain
halo mass based on what is directly observable in
galaxy surveys. Finding the observables that have the strongest correlation with
halo mass can also motivate future surveys on which areas to concentrate in detail.
Read the full abstract ▾
General Relativity and Quantum Cosmology
On entropic cosmology, late time acceleration and the quantum bounce
Luis Rey Diaz-Barron, G. E. Pérez-Cuéllar and M. Sabido
In this work, we present a unified entropic description of the
quantum bounce that is present in Loop
Quantum Cosmology (LQG) and dark energy that drives the late time acceleration of the Universe. By considering a minimal area $A_0$ for the Universe and a modified
entropy area constructed as the sum of $S_Q$, $S_{BH}$ and $S_{DE}$, we derive the Friedmann equations. We show that in the limit $A\sim A_0$, there is a critical density that generates the
quantum bounce and depends on the minimal area. Moreover, in the limit $A\gg A_0$ (large Universe) the late time dynamics gives an accelerating scale factor. Therefore, we can argue an entropic origin for the
quantum bounce and dark energy.
Read the full abstract ▾
Geophysics
Effect of style of faulting on the probabilistic characterization of directionality of horizontal response spectral ordinates
Nathan Girmay and Eduardo Miranda
Horizontal earthquake ground motions exhibit substantial changes in amplitude with changes in orientation. While the effects of style of faulting on central tendency measures of ground motion intensity such as RotD50 are well established in ground motion models, less
attention has been given to how faulting mechanism influences the complete directional characteristics of ground motions. This study addresses this gap by conducting a comprehensive probabilistic characterization of ground motion directionality for strike-slip and reverse-slip earthquakes using 3,862 records with moment magnitudes greater than five. Two directionality parameters were examined across 58 oscillator periods ranging from 0.01 to 10 s. The directionality parameters examined consist of pseudo-acceleration response spectral ordinates at all non-redundant orientations normalized by either RotD100 or RotD50 intensities (denoted as {\eta} and {\nu}, respectively). Nonlinear regression was used to develop mechanism-specific models for the
geometric mean, logarithmic standard deviations, and full probability distributions of these parameters. Results show that strike-slip earthquakes exhibit notably different directionality compared to reverse-slip earthquakes, particularly at longer periods. Strike-slip earthquakes are, on average, 1% to 44% more polarized than reverse-slip earthquakes at periods above 0.5 s, and have RotD100/RotD50 ratios that are 1% to 3.7% larger. The developed models enable engineers and engineering seismologists to obtain mechanism-specific estimates of pseudo-acceleration response spectral ordinates at specific orientations, for applications such as regional seismic risk assessments and orientation-specific probabilistic seismic hazard analyses.
Read the full abstract ▾
Quantum Physics
Entanglement battery and entanglement catalyst in local state discrimination problems
Saronath Halder, Aby Philip and Alexander Streltsov
In this work, we study the limitations and advantages of using
entanglement battery and
entanglement catalyst in local state discrimination problems. We consider both cases of such tools, i.e., exact and approximate cases. We show that to distinguish any set of orthogonal pure bipartite entangled states perfectly under local operations and classical communication using an (exact)
entanglement battery or an (exact)
entanglement catalyst, it is necessary to consider that the cardinality of the set must be smaller than the total dimension of the given
Hilbert space. Then, we construct a nontrivial case where an exact
entanglement battery can provide huge advantage. We also construct other nontrivial cases where exact or approximate
entanglement battery or
entanglement catalyst can be useful. In fact, we find that the approximate tools are particularly useful in the local discrimination of certain sets which can be derived from many-copy indistinguishable ensembles.
Read the full abstract ▾
General Relativity and Quantum Cosmology
Notes on Kerr-Bertotti-Robinson Spacetime
Yu-Sen Zhou, Liang-Bi Wu, Ming-Fei Ji et al. (+3 more)
The surface $r=\infty$ of the Kerr–Bertotti–Robinson (KBR) spacetime is not the collection of the endpoints of infinitely extended light rays, and the Coulomb type component of gravitational field strength represented by $\Psi_2$ remains nonvanishing there, indicating that this surface is not a real boundary. We construct a natural extension across this surface, which connects the exterior of one KBR region to the interior of a neighboring one and, upon iteration, produces an infinite chain of regions connected by wormhole-like bridges. The extension also exposes the neighboring ring singularity without an intervening horizon, challenging the weak
cosmic censorship
conjecture and raising the question of whether the extended geometry is stable under perturbations. We therefore study the quasinormal modes (QNMs) of a test massless scalar field on a two-universe scattering segment. For axisymmetric perturbations, the existence of purely imaginary unstable QNMs is analytically proved for every $\ell$, with their origin tied to the chronology-violating region. In the $(\ell,m)=(2,2)$ sector, unstable QNM branches driven by a black-hole-bomb mechanism are found. Finally, the wormhole geometry produces a double-barrier cavity and families of weakly damped QNMs, suggesting echo-like responses.
Read the full abstract ▾
All authors Yu-Sen Zhou, Liang-Bi Wu, Ming-Fei Ji, Wen-Tao Fu, Li-Ming Cao, Rong-Gen Cai
High Energy Physics (Theory)
Classical and Quantum Chaos from Foundations to Holography
Bhasker Shukla
These notes develop the diagnostics of chaos from their classical definitions through to holography, in six lectures given at the ST4 Workshop, Chennai Mathematical Institute, in 2026. No prior exposure to chaos theory is assumed. Lectures 1 and 2 define classical chaos geometrically and build the instruments that measure it, every one of which reads a phase-space trajectory. Quantization removes that trajectory, and Lectures 3 and 4 rebuild the instruments from spectra and eigenstates instead: level statistics, random
matrix theory, the spectral form factor and eigenstate thermalization, as much the working toolkit for thermalization in many-body physics as for holography. What they return is a classification and a count rather than a rate. Lecture 5 recovers the rate from the squared commutator, treats scrambling as operator growth, follows the commutator to the out-of-time-order correlator, marks where that diagnostic stops being reliable, and reaches the butterfly velocity and the chaos bound. Lecture 6 constructs the eternal black hole, the thermofield double and the shock-wave geometry behind that bound, then follows two probes whose exponents discriminate between backgrounds where the horizon result cannot, one tracking a thermodynamic phase transition, the other resolving an anisotropy induced by a background field. That last part is research rather than review, and every figure throughout is computed from the scripts supplied with the source rather than redrawn from the literature. Every lecture closes with exercises. Claude Opus 5, an AI assistant developed by Anthropic, worked as a research assistant under the author's direction.
Read the full abstract ▾
Quantum Physics
Connectivity–Interference Competition in Coherent Transport on Percolated Hierarchical Small-World Networks
Miquéias Jacinto Cirino and Marcos César de Oliveira
Adding links generally improves classical transport by increasing the number of available paths. We show that coherent
quantum transport can display the opposite behavior. Using continuous-time
quantum walks on a percolated hierarchical small-world network, we identify a coherent overconnectivity penalty: root-to-boundary transport is maximized at intermediate bond probability and decreases as the network approaches full connectivity. The effect is quantified by the final-layer limiting probability $\chi_N$ and by the penalty $P_Q=1-\chi_N(p=1)/\max_p\chi_N(p)$, which measures the loss caused by making the architecture fully connected. The optimum results from a competition between shortcut-assisted spreading and interference-induced intra-layer recirculation. Spectral analysis shows that bond dilution creates motif-induced degeneracies and reorganizes the eigenstates connecting the root to the outermost layer. A comparison with dephased and classical transport shows that the non-monotonic landscape is not a purely geometrical percolation effect, but a coherent architecture-dependent phenomenon. These results provide a design principle for coherent transport in disordered photonic and
quantum-network architectures.
Read the full abstract ▾
Materials Science
Avalanche-like Plasticity in Complex Concentrated Alloys: A Review Across Scales
Michal Knapek, Tomáš Tayari, Kristián Máthis et al. (+1 more)
Complex concentrated
alloys (CCAs), including high- and medium-
entropy alloys, deform in chemically heterogeneous energy landscapes where dislocation glide, solute aging, twinning, phase transformation and microstructural barriers may all contribute. This review discusses avalanche-like and serrated plasticity in CCAs across scales. The first part separates the relevant length scales and methods used to access them. At microscopic and mesoscopic scales, acoustic emission (AE) and microcompression studies reveal discrete dislocation avalanches and strain bursts that may be hidden in conventional macroscopic curves. At the specimen scale, local extensometry and digital image correlation (DIC) studies of the Portevin-Le Chatelier effect show how collective defect dynamics can organize into deformation bands and macroscopic stress serrations. Together, these approaches show that plastic flow may appear smooth only as an average response, while remaining intermittent at finer scales. The second part reviews direct CCA evidence, with emphasis on AE, stress-serration statistics, microplasticity, DIC, nanoindentation and small-scale deformation. A central conclusion is that serrated flow in CCAs should not be treated as a single phenomenon. Depending on chemistry, temperature, strain rate and microstructure, it may originate from dynamic strain aging, twinning, martensitic transformation, slip localization, or a combination of these mechanisms. Reported power-law-like distributions and exponents partly overlap with those known from simpler
crystals and
alloys, and the present evidence does not establish a distinct CCA-specific universality class. CCAs are therefore best viewed as tunable systems in which chemical disorder, short range order, phase stability and microstructure can modify the nucleation, arrest and synchronization of collective plastic events.
Read the full abstract ▾
All authors Michal Knapek, Tomáš Tayari, Kristián Máthis, Miloš Janeček
Earth and Planetary Astrophysics
No Persistent Helium Absorption in LHS 1140 b: Four JWST/NIRISS SOSS Transits and Multi-epoch Stellar He I Variability
Amélie Gressier, Charles Cadieux, René Doyon et al. (+4 more)
The search for atmospheres on temperate terrestrial
planets is important for understanding how these objects form and evolve, and their potential habitability. Recent transit observations of LHS 1140 b, a temperate ($T_{\rm eq}=226$ K)
planet straddling the radius valley ($R_{\rm p}\approx1.7 R_\oplus$), with the WINERED high-resolution spectrograph yielded a detection of planetary atmospheric escape through the measurement of excess absorption ($1.24\pm0.23\%$) in the metastable helium triplet, although a later second visit resulted in a non-detection. We analyze four transits of LHS 1140 b and two of LHS 1140 c observed with JWST/NIRISS SOSS. We find no evidence of helium absorption in either
planet, with all amplitudes consistent with zero within $1\sigma$. For LHS 1140 b, we derive $3\sigma$ upper limits of $0.72$–$1.21\%$. Individual visits disfavor the reported WINERED absorption at $2.6$–$3.7\sigma$, while their joint constraint disfavors a persistent signal at $4.5\sigma$. We find that the
stellar He I line of LHS 1140 varies substantially between NIRPS and WINERED epochs, with both its strength and fractional variability consistent with the behavior of other M
dwarfs. We also identify a moderate correlation between the 2024 He I depth and seeing, suggesting a possible seeing-dependent instrumental contribution. If the high-resolution detection is indeed planetary, the rate of such atmospheric loss events must be relatively low ($f=22_{-12}^{+17}\%$). Alternatively,
stellar He I variability may contribute to the reported excess absorption. Additional high-resolution observations, both in and out of transit, are required to distinguish between these scenarios.
Read the full abstract ▾
All authors Amélie Gressier, Charles Cadieux, René Doyon, Louis-Philippe Coulombe, Romain Allart, Étienne Artigau, François Bouchy
Materials Science · Cross-listed from cs.LG
Enhancing EBSD throughput of battery electrode materials using super-resolution generative adversarial networks
John Mangum, Andrew Glaws, Francois Usseglio-Viretta et al. (+2 more)
Quantitative microstructural characterization of Li-ion battery electrode materials using electron backscatter diffraction (EBSD) has been proven as a critical method for optimizing
cell performance. However, the inherently slow nature of EBSD can hinder the throughput of analyses needed for statistical representation of a material microstructure being developed. This work demonstrates a machine learning super-resolution framework using a generative
adversarial network (SRGAN) to significantly increase EBSD throughput. The SRGAN model was trained on EBSD data of LiNixMnyCozO2 (NMC) cathode particles to computationally enhance low-resolution
datasets and its performance is compared against classical interpolation methods across various upscaling factors (2x to 12x). Both qualitative image metrics and quantitative microstructural analysis verified that the SRGAN systematically outperformed classical methods, particularly in preserving small grains and maintaining realistic grain boundaries. We demonstrate that a 5x upscaling factor, corresponding to a 25x speed-up in acquisition time or a 25x larger field of view, is practical while maintaining acceptable accuracy in key metrics like grain size and shape. For instance, at 5x upscaling, relative errors were +5.7%, +8.2%, and -14.6% on grain area-equivalent diameter, grain maximum sphere-inscribed diameter, and grain boundary length, respectively. The SRGAN methodology developed in this work significantly enhances the efficiency of EBSD acquisition for more statistically robust microstructural
dataset, enabling EBSD as a high-throughput characterization tool for materials research and industrial process development.
Read the full abstract ▾
All authors John Mangum, Andrew Glaws, Francois Usseglio-Viretta, Steven Spurgeon, Donal Finegan
Materials Science
JANUS: A Multi-modal Foundation Neural Sampler for Disordered Materials
Denis Blessing, Mouyang Cheng, Maximilian Schebek et al. (+4 more)
Disordered materials are central to modern technologies, from high-performance
alloys to
quantum devices, yet understanding and designing them requires exploring an enormous space of compositions and atomic arrangements. Here we introduce JANUS, a
multimodal neural sampler that jointly explores chemical composition, atomic structure and volume, learning directly from the energy of the system without requiring pre-generated
equilibrium configurations. Across test systems, JANUS reproduces reference
equilibrium properties and recovers free energy and phase behavior with about three orders of magnitude fewer energy evaluations than reference Monte Carlo sampling. In multicomponent
alloys, JANUS reproduces experimentally observed local chemical order and can be steered to further enhance chemical order and stiffness. Coupled to an evolutionary
language model
agent, it also enables efficient design of
alloys with balanced optical and mechanical properties. Beyond
alloys, JANUS explores vacancies and dopants spanning 15 elements in
semiconductors including silicon and diamond, recovers established defects including the silicon $E$ centre, and identifies new candidate defect pairs and triplets for
quantum engineering, including S-Ti in silicon and B-[O]-O in diamond, with deep in-gap states validated by hybrid-functional density functional theory. By unifying exploration across composition, atomic arrangement and volume, JANUS opens a new avenue for understanding, characterizing and designing chemically disordered materials.
Read the full abstract ▾
All authors Denis Blessing, Mouyang Cheng, Maximilian Schebek, Jutta Rogal, Mingda Li, Carles Domingo-Enrich, Yuanqi Du
Instrumentation and Detectors
Identifying Cost-Favorable Locations for Cosmic Explorer
Laurence Datrier, Geoffrey Lovelace, Tooba Ansar et al. (+19 more)
Cosmic Explorer (CE) is a proposed next-generation gravitational-wave observatory that aims to extend our gravitational-wave
vision to the edge of the observable universe. With a foundation of technology proven by the National Science Foundation's
Laser Interferometer Gravitational-Wave Observatory (LIGO), CE will observe black holes and
neutron stars across
cosmic time, explore the nature of extreme matter with high fidelity, and probe the nature of
gravity and fundamental physics. CE's reference design consists of two widely separated L-shaped detectors to be located in the conterminous United States, one with 20 km arms and one with 40 km arms. As of 2026, CE is in its design and site evaluation phase, with plans to begin observing in the early 2040s together with the Einstein
Telescope in Europe. The size of CE observatories—up to an order of magnitude larger than the 4 km LIGO observatories—presents a significant challenge for identifying suitable candidate sites where CE will achieve its science goals, be built within cost boundaries, attract and retain a workforce, and align with community values. In this paper, we report on the design and use of a Python package, the
Cosmic Explorer Location Search (CELS) package, to identify cost-favorable sites for CE. For a specified detector location and L-shaped geometry in the conterminous United States, CELS estimates site-preparation costs associated with excavation, land clearing, and land acquisition, while accounting for the scientific effects of detector tilt, arm length, and arm opening angle. After describing the package's methods, we present results for a national-level cost and positioning analysis that complements a recent national suitability analysis. We also discuss how future improvements to CELS will allow deeper, more local studies as the
Cosmic Explorer team narrows its list of potential locations.
Read the full abstract ▾
All authors Laurence Datrier, Geoffrey Lovelace, Tooba Ansar, Lance Blagg, Warren Bristol, Matthew Evans, Chris Lukinbeal, Vuk Mandic, Kiet Pham, Jocelyn Read, Sarmad Rameez, Amber Romero, Oscar Romero, Babatunde Isaac Rotimi, Joshua B. Russell, Andrew Saenz, Francois Schiettekatte, Robert Schofield, David H. Shoemaker, Bretton Simpson, Bram J.J. Slagmolen, Joshua R. Smith
Mesoscale and Nanoscale Physics
Ultra-low energy (20 - 300 eV) electron imaging and diffraction
Tatiana Latychevskaia
The lecture discusses the properties of low-energy electrons compared to the electrons of conventional energies employed in commercial transmission electron microscopes. Low-energy electron diffraction and low-energy electron holography principles and experimental schemes are presented and discussed.
Read the full abstract ▾
Materials Science
Local Structure and Dynamics of Three-Dimensional Covalent Organic Frameworks
Francesco Tavani, Saber Mirzaei, Jian Yin et al. (+6 more)
Resolving and controlling the local dynamical properties of covalent organic frameworks (COFs) remains a central challenge, particularly when assembled from large, flexible building units. Here, we combine synchrotron X-ray pair distribution function (PDF) analyses with machine learning-accelerated molecular dynamics (MD) simulations to resolve the local structure and dynamics of two three-dimensional imine-linked COFs, COF-682 {[(DHP)(TAM)]$_{imine}$}, assembled from 6,13-dihydropentacene (DHP) and tetrakis(4-aminophenyl)methane (TAM), and COF-612 {[(HBC-LA$_{12}$)(HAPT)$_2$]$_{imine}$}, assembled from nanographene dodecabenzaldehyde hexakis{[3,5-bis($p$-formylphenyl)-4,6-dimethoxyphenyl]}hexabenzocoronene (HBC-LA$_{12}$) and 2,3,6,7,14,15-hexa(4-aminophenyl)triptycene (HAPT). Validated against the experimental PDFs through ensemble-averaged calculations, the simulations show that the exposed $\pi$-surface and V-shaped geometry of the DHP linker endow COF-682 with enhanced local flexibility through face-to-face and offset $\pi$-stacking interactions differing in both their average interplanar separation and their ring-plane tilt angle. In contrast, the extended nanographene linker rigidifies COF-612 by maintaining the planarity of its fused cores, while the linker pendant aryl rings equip both COFs with enhanced librational ability. The simulations further provide quantitative measures of the translational and reorientational mobility of the linkers, revealing how local COF dynamics may be tuned by balancing non-covalent interactions and different degrees of aromatic
rigidity. The PDF-MD experimental-computational approach holds promise as a general method beyond conventional crystallography to gain insights into the local properties of COFs with the aim of directing their dynamic function.
Read the full abstract ▾
All authors Francesco Tavani, Saber Mirzaei, Jian Yin, Yen-hsu Lin, Caden Myers, Cheng-Hung Lin, A. M. Milinda Abeykoon, Simon J. L. Billinge, Omar M. Yaghi
Quantum Physics
Quantum circuit optimization using deep reinforcement learning: Applications across multiple gate sets
Khoa Dang Tao, Sumin Jin, Muhammad Raza et al. (+1 more)
The practical implementation of
quantum algorithms on noisy intermediate-scale
quantum devices encounters operational limitations due to decoherence and other sources of noise inherent in real hardware. To mitigate these errors while preserving the original functionality of the
algorithm, shorter
quantum circuits are therefore preferred. This motivates the development of effective
quantum circuit optimization
algorithms. Learning-based approaches have emerged as a leading candidate, yet existing autonomous
agents remain inefficient, spending most of their training capacity rediscovering elementary reductions that deterministic rule-based methods already handle reliably. To address this challenge, we propose a reinforcement learning framework that embeds a deterministic Commutation-and-Reduction (CR)
algorithm directly into the training environment. After every
agent action, the CR
algorithm automatically resolves elementary commutations and cancellations, enabling the
agent to focus its learning capacity on the non-trivial optimizations where reinforcement learning adds real value. Empirical evaluation across two gate sets, the universal Clifford+T basis and the CNOT+Pauli basis, shows that RL+CR produces shorter
circuits than a standard RL
agent at all tested scales. We demonstrate that RL trained on smaller
quantum circuits can be applied to larger
quantum circuits. On 20-
qubit Clifford+T
circuits, five times larger than the training
circuits, RL+CR removes twice as many gates as standard RL. This work provides a robust approach that could accelerate the compilation and optimization processes for future fault-tolerant and utility-scale
quantum systems.
Read the full abstract ▾
All authors Khoa Dang Tao, Sumin Jin, Muhammad Raza, Changhyoup Lee
Instrumentation and Methods for Astrophysics
Real-Time RFI Mitigation in SPOTLIGHT: A Two-Stage Approach for Transient Searches
Raghav Wani, Jayanta Roy, Harshavardhan Reddy et al. (+10 more)
Radio Frequency Interference (RFI) remains one of the primary challenges limiting the sensitivity and reliability of modern
radio transient surveys, particularly for real-time searches of fast
radio transients. The SPOTLIGHT system is a commensal real-time transient search backend operating at the upgraded
Giant Metrewave
Radio Telescope (uGMRT), where robust and computationally efficient RFI mitigation is essential for sustained operations. We present the real-time two-stage RFI mitigation framework developed for SPOTLIGHT, comprising an
antenna-level voltage-filtering module (VOLT) operating prior to correlation beamforming and the SPOTLIGHT Time-domain RFI Processing Engine (STRIPE), a statistical RFI-filtering framework applied to beamformed data. Together, these complementary techniques mitigate a broad spectrum of RFI, ranging from broadband impulsive interference mitigated by VOLT to narrowband spectrally confined spurious signals mitigated by STRIPE, while remaining computationally efficient enough to satisfy the stringent requirements of real-time processing. The framework is evaluated using routine commensal GMRT observations, controlled 76
pulsar observations, and benchmarking against PRESTO's rfifind. The deployed system reduced the false detection rate by 98%. The recovered astrophysical pulses exhibit a 2.7x improvement in S/N after the two-stage filtering compared with the unfiltered data. These improvements enhance SPOTLIGHT's detection efficiency, sensitivity, and operational reliability, strengthening its capability to discover
radio transients with the uGMRT.
Read the full abstract ▾
All authors Raghav Wani, Jayanta Roy, Harshavardhan Reddy, Sanjay Kudale, Ujjwal Panda, Karel Adamek, Wesley Armour, Kshitij Bane, Kaushal Buch, Jayaram Chengalur, Jyotirmoy Das, Sridhar Gajendran, SPOTLIGHT Collaboration
Earth and Planetary Astrophysics
Wet Removal and Cloud Enhancement: The Microphysics of Cloud-Haze Interactions on Sub-Neptunes
Vighnesh Nagpal, Maria Steinrueck, Diana Powell et al. (+3 more)
Aerosols are a near-ubiquitous feature of sub-Neptune atmospheres, yet their microphysical nature remains poorly understood. Both condensate clouds and photochemical hazes have been proposed to explain observations, but have largely been studied in isolation. Here we present a new bin-scheme microphysical model, adapted from CARMA, that couples cloud and haze formation through heterogeneous nucleation - the dominant mode of cloud formation in the
Solar System - in which haze particles act as cloud condensation
nuclei (CCN). Applying this model to KCl clouds on GJ 1214 b-like warm sub-Neptunes, we find that the microphysical contact angle $\theta$ between cloud and haze particles governs distinct regimes of aerosol behavior: at moderate contact angles ($25^\circ \lesssim \theta \lesssim 70^\circ$), hazes are efficiently removed from the upper atmosphere through "wet removal" as they seed gravitationally-settling clouds; at small contact angles ($\theta \lesssim 25^\circ$), heterogeneous nucleation instead produces an enhanced population of mixed cloud-haze particles at high altitudes, dramatically increasing aerosol optical depth ("cloud enhancement"). These structural changes produce differences of up to four scale heights in transmission spectra, with strong effects at optical and near-infrared wavelengths relevant to JWST NIRISS/SOSS, while wavelengths beyond about 3 microns remain comparatively unaffected. We map these effects across orders of magnitude in
metallicity, haze production rate, and vertical mixing strength, establishing their generality across sub-Neptune parameter space. Because heterogeneous nucleation is a universal phase-change process, this framework extends naturally to other
exoplanet atmospheres and potentially any astrophysical environments where condensation onto foreign substrates may occur, including protoplanetary disks and
stellar outflows.
Read the full abstract ▾
All authors Vighnesh Nagpal, Maria Steinrueck, Diana Powell, Peter Gao, Dominic Samra, Wolf Cukier
Superconductivity
Large Field-Free Superconducting Diode Effect with Nonmonotonic Polarity Reversals in NbSe$_2$/CrBr$_3$ Heterostructures
Shengbiao Sun, Lang Xiao, Chenghao Shen et al. (+10 more)
The superconducting diode effect (SDE), characterized by nonreciprocal dissipationless supercurrent, offers a promising route toward ultralow-power superconducting electronics. Yet most realizations require an external
magnetic field, and achieving a large, controllable SDE at zero field remains challenging. Here we report a field-free SDE with an efficiency reaching 35.7% in a van der Waals NbSe$_2$/CrBr$_3$
heterostructure, whose polarity is programmable by
magnetic-field history. Unlike conventional mechanisms based on finite-momentum pairing, the SDE originates from the leading
symmetry-allowed cubic term odd in Cooper-pair momentum, which yields unequal critical currents while leaving the
equilibrium condensate at zero momentum. Remarkably, upon sweeping a perpendicular
magnetic field, the diode polarity undergoes nonmonotonic and hysteretic reversals that cannot be explained by Meissner screening or conventional
ferromagnetic proximity. Combining transport measurements, micromagnetic simulations, and a generalized Ginzbur-Landau theory, we attribute these unconventional behaviors to layered ferrimagnetism in CrBr$_3$, where coexisting
ferromagnetic and
antiferromagnetic interlayer couplings produce a history-dependent interfacial exchange field acting on NbSe$_2$. Our results reveal a distinct mechanism for nonreciprocal superconductivity and establish layered van der Waals magnetism as a versatile platform for high-efficiency, programmable, field-free superconducting diodes.
Read the full abstract ▾
All authors Shengbiao Sun, Lang Xiao, Chenghao Shen, Bowen Hao, Jia-Peng Peng, Ziye Zhu, Feiyue Wang, Qilin Han, Ya-Qing Bie, Shuo Wang, Tong Zhou, Dapeng Yu, Ben-Chuan Lin
High Energy Physics (Phenomenology)
Quantum Magic in High Energy Collision
Ying-Ying Li, Ian Low, Yi-Lin Wang et al. (+1 more)
Quantum magic, or nonstabilizerness, is a
quantum resource associated with computational advantage in
quantum systems. In high energy collisions,
Quantum Electrodynamics (QED) is inefficient at generating magic while the weak mixing angle, a fundamental constant of nature, sits near a value that minimizes magic production in charged-
lepton scattering. These observations were made in the laboratory (lab) basis, in which
spin is projected along the incoming beam axis. An alternative choice is the helicity basis, in which
spin is projected along the direction of motion of each particle. The transformation between these two bases is, in general, not a Clifford operation and therefore can change the amount of magic. We present a detailed study of magic production in both bases for QED and electroweak processes, and compare these results with the basis-invariant non-local magic. In the ultra-relativistic limit, magic production is generally smaller in the helicity basis due to helicity selection rules, while the lab basis generally yields less magic in the non-relativistic regime. We provide
circuit realizations of the ultra-relativistic Bhabha amplitudes using linear combinations of
unitaries and show that the lab basis construction contains a larger $T$-gate count at generic scattering angles. Interestingly, in both bases the physical weak mixing angle lies close to the value that minimizes magic production.
Read the full abstract ▾
All authors Ying-Ying Li, Ian Low, Yi-Lin Wang, Zhewei Yin
Quantum Physics
Realizing Logical Diagonal Gates via Transversal Physical $Z$-Rotations in CSS Codes
K. Sai Mineesh Reddy and Navin Kashyap
Calderbank-Shor-Steane (CSS) codes, constructed from nested classical codes $C_2 \subseteq C_1$, are typically optimized for good code parameters. However, practical
quantum computing equally demands fault-tolerant logical gates. In this work, we characterize nested pairs $(C_1, C_2)$ whose resulting CSS codes realize a target logical diagonal gate via transversal physical $Z$-rotations. In doing so, we recover a result of Camps-Moreno et al. that CSS codes can realize only logical single-
qubit $Z$-rotations and multi-
qubit controlled $Z$-rotations via transversal physical $Z$-rotations. Building on our characterization, we develop the ”appending construction”, that takes as input an $[[n',k']]$ CSS code $Q'$ and a target logical $Z$-rotation (single-
qubit or multi-controlled) $U_L$, and extends $Q'$ by systematically appending $n''$ physical
qubits to obtain an $[[n,k]]$ CSS code $Q$ with $n = n'+n''$ and $k=k'$. The target logical gate $U_L$ is realized in $Q$ by applying a well-chosen physical transversal $Z$-rotation to the $n''$ appended physical
qubits. Moreover, any logical gate realized via transversal physical $Z$-rotations in the input code $Q'$ remains transversally realizable in the extended code $Q$. The CSS code $Q$ may incur a loss in minimum distance, but the loss can be controlled through the parameter choices made in the construction. By repeatedly applying the appending construction, we can extend any CSS code $Q'$ to obtain a CSS code $Q$ that supports fault-tolerant implementations of multiple desired logical $Z$-rotations. The cost to be paid for this is the increased physical
qubit overhead as the number of target logical gates grows. To illustrate our methodology, we construct CSS code families that transversally realize addressable logical single-
qubit and multi-controlled $Z$-rotations.
Read the full abstract ▾
Quantum Physics
Non-Local Search-to-Decision Reduction over F2, and More
Prabhanjan Ananth
Non-local search-to-decision asks whether the difficulty of two non-communicating (non-local) parties both predicting x given a bipartite state (that possibly depends on x) implies the difficulty of non-local parties both predicting the inner product <r,x>, for a uniformly random r. This problem and its variants have been extensively studied and are motivated by applications to unclonable cryptographic primitives such as unclonable encryption and copy-protection. We study the identical-challenge setting, in which both parties receive the same uniformly random vector r, in contrast to the independently sampled challenges considered in prior works. We demonstrate positive results for the cases when $x$ and r are vectors over F_2 and over large finite fields. As a consequence, we obtain a conceptually different proof of indistinguishability-secure unclonable encryption.
Read the full abstract ▾
Superconductivity
Ultrasonic attenuation in inhomogeneous superconductors
Aman Sardwal, Andreas Kreisel and Shantanu Mukherjee
Subgap bound states can produce pronounced features in the density of states without necessarily giving rise to a corresponding signal in ultrasonic attenuation. We show that the coherence factors act as a filter for the contribution of bound states to ultrasonic attenuation. In a phase-biased
superconductor–normal–
superconductor junction, the Andreev bound states produce a resonance in the attenuation when the
phonon frequency matches the phase-dependent separation between the subgap levels. The situation is different at a $(110)$ grain boundary in a $d_{x^2-y^2}$
superconductor. There, nonmagnetic
impurity-induced bound states remain weak in the attenuation despite their large spectral weight, because the relevant coherence factors nearly cancel. When local magnetism develops near the boundary, this cancellation is removed, the bound states become
spin split, and a clear attenuation peak appears, which we argue is governed by a process involving emission of
phonons by pair of quasiparticles at low temperatures. We obtain these results using a real-space Bogoliubov–de Gennes formulation of ultrasonic attenuation and
benchmark the method against the known low-temperature behavior of homogeneous $s$- and $d$-wave
superconductors. The results show that ultrasound can distinguish bound states with similar spectral signatures but different
symmetry and
spin structure.
Read the full abstract ▾
Biological Physics
Elongation suppresses rheotaxis and enables microfluidic enrichment of e̱ta}-lactam-resistant bacteria
Ran Tao, Nathaniel C. Esteves, Jay Zhu et al. (+1 more)
Antimicrobial resistance (AMR) complicates the treatment of diseases including lung and urinary tract infections (UTIs), which are among the most common bacterial infections worldwide. Motile pathogens can use rheotaxis to swim upstream against fluid flows, potentially promoting access to upper regions of anatomical tracts. However, it remains unclear how antibiotic exposure and resistance influence this transport process. Here, using single-
cell tracking microscopy, we investigate how elongation induced by e̱ta}-lactam antibiotics affects the rheotactic migration of E. coli in confined microfluidic channels. Remarkably, we find that rheotaxis can be inhibited 100-fold by antibiotics, even if the susceptible elongated
cells remain fully motile. However, resistant bacteria remain short and retain upstream migration under the same conditions. Using genetically engineered bacteria with tunable
cell length, we show that the underlying mechanism that governs rheotaxis is the coupling between
cell morphology and flow vorticity, where elongated
cells are rapidly rotated downstream. Finally, we exploit this length-dependent transport difference to separate short and elongated
cells under flow and enrich ampicillin-resistant
cells from mixed populations. Together, these results establish bacterial elongation as a key control parameter for rheotactic transport, and provide a proof-of-concept strategy for enriching e̱ta}-lactam-resistant bacteria for potential use in rapid AMR detection.
Read the full abstract ▾
All authors Ran Tao, Nathaniel C. Esteves, Jay Zhu, Arnold J. T. M. Mathijssen
Solar and Stellar Astrophysics
Asteroseismology of the multiperiodic field SX Phe pulsator BL Camelopardalis
W. Szewczuk, J. Daszyńska-Daszkiewicz, P. Walczak et al. (+1 more)
BL Camelopardalis (BL Cam) is the most metal-poor SX Phoenicis
star known in the
Galactic field, making it an excellent test bed for studies of Population II
stellar structure and
evolution, as well as for investigating the formation channels of blue straggler
stars. We aim to constrain fundamental
stellar parameters and pulsational properties of BL Cam and identify the nature of its observed oscillation modes. We analysed high-precision space-based data from the TESS mission and long-term ground-based observations from the Zwicky Transient Facility (ZTF) survey. The ZTF data were primarily used to derive the orbital parameters of the system, while the TESS light curves enabled us to extract a rich oscillation spectrum. We identified multiple pulsation frequencies and performed seismic modelling using a
Bayesian approach. We detected numerous pulsation frequencies, including a dominant radial mode and additional non-radial components. We predicted all fitted modes in our seismic models as excited. The models reproduced the two highest amplitude-independent frequencies (i.e. the radial fundamental mode and a dipole mode) and suggested the possible presence of additional radial overtones. The inferred
stellar parameters confirm the extremely low
metallicity of BL~Cam. We also confirm its binary nature, with an orbital period of 144 days. BL Cam provides a valuable
benchmark for testing
stellar models of metal-poor pulsators. The combination of space-based photometry and
Bayesian seismic modelling enables robust constraints to be placed on its internal structure and pulsation properties.
Read the full abstract ▾
All authors W. Szewczuk, J. Daszyńska-Daszkiewicz, P. Walczak, E. Rodríguez
Strongly Correlated Electrons · Cross-listed from math.AG
Equations of Tree Tensor Network Varieties
Serkan Hoşten, Niharika Chakrabarty Paul, Otto T. P. Schmidt et al. (+1 more)
We show that tree tensor network varieties, including tensor train varieties, are general Markov models associated to spaced trees. This allows us to prove that the
prime ideals of these varieties are generated by minors of
matrix flattenings. In the case of tensor train varieties, we discuss whether these minors form a Gröbner basis and provide a combinatorial method to compute the degree for order $3$ tensor trains.
Read the full abstract ▾
All authors Serkan Hoşten, Niharika Chakrabarty Paul, Otto T. P. Schmidt, Dmitry Skurt