Quantum Physics · Cross-listed from cs.NI
Priority-Aware Routing for Quantum Networks:Integrating Coherence-Time Constraints into Scheduling
Sadhgun Ram Dasi and Aswath Babu H
Quantum networks face a fundamental challenge absent in classical networks; finite
memory coherence times mean that queuing delay directly degrades information quality, causing decoherence that has no classical analog. Existing routing protocols optimize for hop count or channel fidelity while treating scheduling delays as a secondary concern, leaving fidelity vulnerable to congestion-induced decoherence. We present a coherence-aware routing protocol that integrates decoherence constraints into path selection via a priority-modulated aging model derived analytically from Weighted Fair Queueing theory, where high-priority traffic receives compressed effective queue delay. We build a custom discrete-event simulator verified against NetSquid (across 104 states), and evaluate across two structurally diverse
topology classes under identical physical parameters, isolating
topology structure as the sole independent variable. In all experiments, our protocol is benchmarked against loss-only Dijkstra routing and FIFO scheduling as baselines. On
topologies, P2 traffic achieves 96.08% fidelity under a 9x load increase with only 0.04 percentage point degradation, versus a 13.51 percentage point collapse for the loss-only baseline; P2 tail latency holds stable at 0.055 ms while Dijkstra degrades 5.5x. On Barabasi-Albert scale-free
topologies, our protocol delivers a +4.12 percentage point fidelity advantage with 97.8% higher aggregate throughput at operational loads over the baseline, with a clearly characterized hub-saturation boundary at 160k QPS. FIFO scheduling provides negligible priority differentiation on both
topology classes, providing strong evidence that coherence-aware routing-not scheduling alone is responsible for the observed QoS gains.
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Physics and Society · Cross-listed from cs.CL
Doc2LoRA Provides Decodable Representations of Scientific Ideas
Chand Sahil Mansuri, Joel Zachariah and Sadamori Kojaku
Representing scientific papers as points in a space lets us search for similar papers and inquire about how fields relate to one another and drive innovation. Beyond search, the vector space of papers invites generation: mixing papers through simple vector operations creates new points, mirroring combinatorial novelty, the recombination of existing ideas into new ones. However, a mixed point often represents an idea no paper has yet realized, with no papers nearby to identify the idea. We propose representing each paper by a LoRA adapter generated by the Doc-to-LoRA hypernetwork. Every point in the space, including mixtures, thus represents a large
language model (LLM) open to questions and instructions in natural
language. On papers from the American Physical Society (APS), we instruct the LLM at the average of each subfield to name the field in a few words and obtain labels closer to the official names than the labels of five baselines, as judged by word overlap and a panel of five LLM judges. We also ask the LLMs at points between two APS papers to write an abstract and obtain descriptions shifting from one paper to the other in step with the mixing weight. While Doc-to-LoRA is trained for generation, a small invertible transform makes the
embeddings competitive for search, on par with SPECTER2 and EmbeddingGemma and close to SBERT. Because the transform is invertible, every point in the transformed space still maps back to an LLM. The
embeddings thus serve both search and generation, enabling researchers to question the idea at any point in the space as a starting point for generating new ideas.
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High Energy Astrophysical Phenomena
NEXUS: Discovery of a Luminous Young Transient at $z=5$
Ming-Yang Zhuang, Yue Shen, Lei Hu et al. (+8 more)
We report the discovery of AT 2026abck, a young transient in a
star-forming
galaxy at $z=5.017\pm0.001$, identified from Year-2 observations of the NEXUS JWST treasury program. AT 2026abck was detected on 2026 Aug 7 in NIRCam F200W imaging, with contemporaneous detection from parallel NIRCam F150W+F277W imaging. It brightened by $>1.4$ mag in F200W over $\lesssim 12$ rest-frame days, as inferred from the last non-detection. AT 2026abck has nearly identical magnitudes of $\sim27.4$ mag in F150W, F200W, and F277W, and is undetected in F444W ($>27.9$ mag, 3$\sigma$). It is the first robustly detected $z\gtrsim 5$ transient in a non-
lensing field. A blackbody fit yields a hot photosphere ($\sim1.7\times10^4\, \mathrm{K}$) with a radius of $\sim7\times10^{14}$ cm ($\sim46$ au) and a bolometric luminosity of $\sim3\times10^{43}\, {\rm erg\, s^{-1}}$. Its off-
nucleus location and hot, UV-bright SED favor a core-collapse
supernova origin, while its temperature and luminosity exceed those of normal SNe II at comparable early phases. We estimate that AT 2026abck was detected $\sim4$-10 rest-frame days after explosion. The host is an intermediate-mass ($M_*\approx10^{9.8}\,M_\odot$),
star-forming (${\rm SFR}\approx20\,M_\odot\,{\rm yr^{-1}}$)
galaxy on the $z\approx5$ main sequence, $\sim3.3$ dex more massive than the ultra-faint host of the lensed SN Eos at $z=5.13$. Together, the two events show that CCSNe at $z>5$ occur across a wide range of host environments, and AT 2026abck demonstrates that high-cadence blank-field JWST surveys can capture high-
redshift SNe during their early, UV-bright phase.
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All authors Ming-Yang Zhuang, Yue Shen, Lei Hu, Justin D. R. Pierel, Zhiwei Pan, Zachary Stone, Adam J. Burgasser, Xiaohui Fan, Jenny E. Greene, Junyao Li, Feige Wang
Soft Condensed Matter
Geometry and Mechanics of Ribbon Gridshells
Daniel Castro, Joo-Won Hong, Étienne Reyssat et al. (+3 more)
Mechanical metamaterials exhibit anomalous properties induced from non-trivial mesoscopic constituents. Inspired from architectural and industrial structures, we introduce arrangements of long, narrow ribbons intersecting at prescribed angles as a model thin-sheet metamaterial. These ribbon gridshells are shown to display highly non-linear behavior driven by the
geometric constraints, nonetheless unlike most complex mechanical systems, we are able to explicitly write out the coarse-grained governing equations and to classify their solutions in terms of the intersection patterns of the ribbons. It is shown that the structure can assume arbitrary, tunable Gaussian
curvature distributions, allowing us to formulate an inverse design problem, solvable under a suitably defined local condition. An analysis of the soft modes, confirmed by experiment and numerics, reveals rich mechanics which may exhibit both a rigid and an anomalously soft behaviors.
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All authors Daniel Castro, Joo-Won Hong, Étienne Reyssat, José Bico, Benoît Roman, Hillel Aharoni
Biological Physics
The Trajectory Statistics of Biological Exploratory Dynamics
Sara D. Mahdavi, Gabriel L. Salmon, Minakshi Ashok et al. (+4 more)
Biological processes, from molecules diffusing to their regulatory destinations to whales pursuing food or mates, are widely exploratory. Such behaviors are effective when some verifiable functional state or outcome can be reached regardless of initial conditions. In these cases, systems repeatedly undergo distinct and abortive trajectories; the process only ends when the system finds “right” outcomes. This dominance of the terminal condition (and indifference to the initial state) provokes a very different perspective than the conventional “dynamical systems” framework that has been a centerpiece of the quantitative sciences for centuries. We hypothesize that many of these problems defy the initial-condition driven or gradients on landscapes so useful in problems ranging from mechanics to electrodynamics to chemical kinetics to mass and heat transport. We examine several mathematical frameworks that capture and unify key aspects of exploratory dynamics. One powerful way of thinking of such processes is the
geometric distribution, where repeated failures are punctuated by a successful trajectory. We develop intuitions for how random walks with resets accelerate search processes. We highlight fresh and surprising behaviors of search under drift, cues, and checkpoints. Last, appreciating the probability of trajectories conditioned on satisfying macroscopic final outcomes reveals a
language for the potency of variation sculpted by selection in their broadest forms. This can give the fictitious appearance of the future making itself known in the present, but we view this as conceptually similar to the way “fictitious forces” arise in non-inertial reference frames. These approaches stress unity, open questions, and applications across a range of biological phenomena.
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All authors Sara D. Mahdavi, Gabriel L. Salmon, Minakshi Ashok, Madhav Mani, Marc Kirschner, Jane Kondev, Rob Phillips
Quantum Physics
Time-Integrated Leakage as a Dynamical Benchmark for Multi-Mode Superconducting-Qubit Reset
Sushant Sharma and Aswath Babu H
Reset performance in superconducting
qubits is often summarized by the population that remains at the end of the pulse. This is an important number, but it does not describe what happens during the reset itself. A protocol may reach a small final residual while keeping the
qubit in a leakage state for a comparatively long part of the trajectory. In this work, we therefore use time-integrated leakage, together with the usual endpoint population, to study a multi-mode dissipative reset model under flux-frequency control. We examine finite thermal occupation, parameter sweeps, frequency disorder, an auxiliary-chain ablation, and a literature-based rate
benchmark. At the representative ablation point, adding the auxiliary chain reduces Lf from 8.56 to 0.78 ns and shifts the sustained Pf less-than- 10-2 crossing from 39.5 to 9.8 ns. Interestingly, the configuration without the chain still reaches the smaller long-time residual. The two metrics can therefore favor different reset configurations. For the same 300 ns analysis window, an effective rate model built from the f-ket and e-ket decay rates reported by Zhou et al. gives Lf is 108.0 ns, while the complete simulated configuration gives 0.783 ns. We use this only as a kinetic reference and not as a reproduction of the experiment. In the wider set of simulations, thermal occupation is the main source of degradation, while the frequency disorder considered here has a much weaker effect. The results suggest that time-integrated leakage is a useful quantity to report alongside endpoint residuals, especially when reset is part of repeated
quantum-error-correction cycles.
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Quantum Physics
Interferometric Readout of Momentum-Space Topology in a Programmable Dissipative Photonic Circuit
Andrea Cataldo, Emil J. Bergholtz, Daniel Leykam et al. (+2 more)
Topology under non-Hermitian dynamics is encoded in the phase of the bulk
evolution, yet strong dissipation suppresses the amplitudes carrying it. We resolve this using a programmable photonic integrated
circuit that implements such dynamics in synthetic momentum space through
unitary dilation, with the phase recovered by phase-shifted interferometry. For the non-Hermitian Su-Schrieffer-Heeger model, the method distinguishes trivial and non-trivial Zak phases and yields a coherence winding $q=\pm 1$ induced by an exceptional point. Extending to a synthetic
torus via a Rice-Mele pump gives the first Chern number $\mathrm{Ch}_1=0,1$ for trivial and non-trivial cycles, showing a programmable route to momentum-space
topology under strongly dissipative non-Hermitian dynamics.
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All authors Andrea Cataldo, Emil J. Bergholtz, Daniel Leykam, Jun Gao, Ali W. Elshaari
Fluid Dynamics
Three-Dimensional Simulation of Flood Propagation at Syabrubesi, Nepal
Rainald Löhner and Harbir Antil
Three-dimensional flood propagation through the Bhote Koshi–Langtang Khola junction at Syabrubesi, Nepal, is studied using an incompressible free-surface model. The calculation is motivated by the August 2026 flood and examines the passage of an imposed inflow through the local bends and changes in channel width. The Navier–Stokes equations and an interface transport equation are solved on unstructured tetrahedral meshes constructed from pre-event terrain data. For an inlet speed of $10\,\mathrm{m\,s^{-1}}$, the solution indicates surface speeds above $40\,\mathrm{m\,s^{-1}}$. The advancing front spreads across the junction; as the flow develops, water deepens and slows around the bend. Higher speeds persist in the confined upstream and downstream regions.
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Astrophysics of Galaxies
A New Hope for AGN SED Fitting: X-Ray Spectral Analysis of 12MGS AGN with the C2PO-Torus Model
Carys J. E. Gilbert, Lucia Marchetti, Luigi Barchiesi et al. (+8 more)
In this paper, we present the results of comprehensive, broadband X-ray spectral analysis of a subsample of 43 mid-Infrared (IR) selected
star-forming active
galactic nuclei (AGN). We analysed archival NuSTAR, Chandra, and XMM-Newton data, and present the first pointed X-ray observation of IRASF03450+0055. We introduce a new physically-based X-ray spectral model, C2PO-
Torus, based on a two-phase clumpy
torus geometry. It is designed to provide constraints on physical parameters of the
torus that can be directly linked to the parameters of the AGN model SKIRTOR. This model will allow us to exploit the synergies between the X-ray and IR regimes, place stronger constraints on the
torus properties, and improve spectral energy distribution (SED) fitting by providing priors for the SKIRTOR parameters. We compare the results from the C2PO-
Torus fitting to those obtained from traditional models, finding that it is an extremely effective tool for fitting a wide variety of X-ray spectra. We observe that our sample closely follows the established L_[OIII] - L_X AGN relation, while presenting an IR and
Radio excess with respect to the L_X - L_12micron and L_X - L_1.4GHz AGN relations at low luminosities. We believe that this excess is due to contamination from
star formation related emission. We anticipate that the C2PO-
Torus model will aid substantially in completing full-spectrum SED fitting of this sample, allowing us to properly disentangle the different emission components of these objects, which are local analogues of AGN at
Cosmic Noon.
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All authors Carys J. E. Gilbert, Lucia Marchetti, Luigi Barchiesi, Mattia Vaccari, Cristian Vignali, Stefano Marchesi, Francesca Pozzi, Francesco Salvestrini, Anna Feltre, Malebo Moloko, Carlotta Gruppioni
High Energy Astrophysical Phenomena
VLBI Astrometric Procedure and Performance with CHIME/FRB Outriggers
Shion Andrew, Mattias Lazda, Calvin Leung et al. (+15 more)
Precise localizations of fast
radio bursts (FRBs) to specific environments within their host
galaxies with very-long-baseline interferometry (VLBI) have provided valuable insights into the nature of their progenitors. To date, such localizations have relied primarily on traditional VLBI facilities, whose observational capabilities limit them to targeted follow-up on a small subset of repeating FRBs that are observable at frequencies above $\sim$1 GHz. CHIME/FRB Outriggers is a low-frequency (400–800 MHz), wide-field VLBI network designed to overcome these limitations, aiming to localize a substantial fraction of CHIME-detected FRBs to $\sim$50 mas precision. In this work, we detail the analysis procedure used to localize FRBs with the CHIME/FRB Outriggers VLBI array. With over a thousand test localizations consisting of continuum calibrators and
pulsars with known VLBI positions, we provide a comprehensive demonstration of the VLBI array's ability to robustly meet, and under some conditions exceed, the nominal astrometric specification required for the central science goals of CHIME/FRB Outriggers. By demonstrating that a wide-field survey instrument can deliver routine $\sim$50 mas astrometry on one-off FRBs, this work lays the foundation for the upcoming generation of wide-field VLBI FRB surveys and the population-scale FRB samples they will enable.
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All authors Shion Andrew, Mattias Lazda, Calvin Leung, Kiyoshi W. Masui, Danté M. Hewitt, Jacob Willis, Alyssa Atkinson, Kevin Bandura, Shami Chatterjee, Nina V. Gusinskaia, Adam E. Lanman, Juan Mena-Parra, Kenzie Nimmo, Aaron B. Pearlman, Ziggy Pleunis, Alexander W. Pollak, Gurman Sachdeva, Vishwangi Shah
High Energy Astrophysical Phenomena
HESS J1507-622: A Plausible Young Galactic Kilonova Remnant
Prantik Sarmah, Xilu Wang, Myles Carley et al. (+3 more)
HESS J1507$-$622 is an unusual TeV gamma-ray source in the H.E.S.S.
Galactic Plane Survey, distinguished by its off-plane location ($b \simeq -3.5^{\circ}$) and compact angular extent ($\sim 0.3^{\circ}$). Its location and morphology challenge conventional
pulsar wind nebula and
supernova remnant interpretations, and the absence of a detected shell or associated
pulsar leaves its origin unresolved. Here, we propose that HESS J1507$-$622 is a young
Galactic kilonova remnant with gamma-ray emission of leptonic origin. In this scenario, the source's off-plane location is naturally explained by the natal kick imparted to the progenitor binary
neutron star system. We demonstrate that a leptonic kilonova remnant model can successfully reproduce the observed GeV-TeV flux via inverse-Compton scattering from shock-accelerated electrons, while the corresponding synchrotron emission remains below current X-ray and
radio upper limits. Based on the source's energetics and angular size, we infer a distance of 3.8-14.3 kpc and an age of 0.2-3.0 kyr. Importantly, our analysis favors a kilonova remnant younger than 1 kyr. The lack of a historical naked-eye record can be explained by the transient's rapid fading, far-southern declination, and potential line-of-sight extinction. We further assess the detectability of unique multi-wavelength signatures that could confirm this hypothesis. We find promising prospects for detecting the unique MeV gamma rays from the decay of $r$-process radioisotopes using future observatories, alongside complementary low-energy signatures from thermal
dust emission and a possible optical light echo. These distinct signals offer definitive tests of the kilonova remnant interpretation and motivate targeted observations with current and future facilities.
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All authors Prantik Sarmah, Xilu Wang, Myles Carley, Shu-Xu Yi, Ming-Yu Ge, Rebecca Surman
Nuclear Theory
Neutron-nucleus scattering in an $L^2$-integrable basis
Bui Minh Loc and Calvin W. Johnson
First-principles calculations of scattering off
quantum many-body systems such as atoms and
nuclei is important but nontrivial, requiring large-dimension ($10^3$ to $10^8$ or more) bases. For the first time we apply to many-body targets a recently developed approach to find phase shifts in $L^2$-integrable bases, computing
neutron-
nucleus scattering using the same interactions as ab initio models of
nuclei, in very small (dimension 3-6) bases. Our work shows the mean field dominates low-energy
nuclear scattering; it also provides a foundation for more efficient future methodologies.
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High Energy Physics (Phenomenology)
A Partial Wave Formalism for High-Energy Meson Electroproduction
Dillon Leahy, Derek Glazier, Vincent Mathieu et al. (+7 more)
We present a comprehensive partial-wave analysis formalism for
meson electroproduction based on reflectivity amplitudes. By applying parity-based
symmetries, we construct a fully diagonalized framework that relates complex production amplitudes to measurable spherical harmonic moments and
Spin Density
Matrix Elements. We demonstrate that, under the assumption of high-energy Regge factorization, longitudinal and transverse cross sections can be natively separated without requiring beam-energy-varying Rosenbluth separations. We validate this inversion methodology through numerical closure tests and apply it to existing unpolarized $\rho^0$ and $\omega$ electroproduction data from HERMES and COMPASS. The extracted amplitudes align with $s$-channel helicity conservation expectations for the $\rho^0$, while clearly isolating the large unnatural-parity pion exchange contribution in $\omega$ production without model-dependent background approximations. Finally, we systematically generalize the formalism to include initial target and
recoil baryon polarization, establishing the rigorous observables required for complete amplitude extraction, no longer requiring any factorisation assumptions. This unified framework directly supports upcoming spectroscopy and nucleon structure programs at CLAS12, GlueX, and the future Electron-Ion
Collider.
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All authors Dillon Leahy, Derek Glazier, Vincent Mathieu, Marco Filippini, David Ireland, Glòria Montaña, Alessandro Pilloni, Bhawani Singh, Charlie Velasquez, Daniel Winney
High Energy Physics (Theory)
Scaling similarity and generalised conformal symmetry in D2-brane holography
Andrea Conti, Adolfo Guarino and Ricardo Stuardo
We study D2-brane holography within the purely dilatonic sector of four-dimensional maximal ISO(7)-gauged supergravity, obtained as a consistent truncation of type IIA supergravity on S$^6$. In the dual frame, the four-dimensional Lagrangian resulting from the reduction of the massless IIA theory exhibits scaling similarity, thus reflecting the generalised conformal
symmetry of the dual three-dimensional maximally supersymmetric Yang-Mills theory. Using an auxiliary spacetime construction, we show that the
holographic CFT$_3$ fixed points and RG-flows known in the massive IIA theory have natural counterparts in the massless IIA theory: QFT$_3$s with generalised conformal
symmetry connected by generalised RG-flows, which we construct numerically. We also revisit the Coulomb branch solutions and propose an extension of Gubser's singularity criterion to supergravity theories exhibiting scaling similarity.
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Quantum Physics
Collective Dynamics in Spin Chains with Constrained Dissipation: Classically Fragile but Quantum Robust
Pietro Brighi, Gianluca Frazzei, Igor Lesanovsky et al. (+2 more)
Collective non-
equilibrium phenomena in many-body systems are strongly influenced by fluctuations, particularly in the vicinity of phase transitions, where the interplay between classical and
quantum effects can alter cooperative behavior. Here, we investigate this classical-
quantum competition in a kinetically constrained
spin chain, the dissipative far-East model. In absence of fluctuations, the system exhibits emergent collective dynamics, resulting in phase coexistence. We find that this phenomenon is robust to
quantum fluctuations, which further stabilize it, whereas classical fluctuations suppress phase coexistence at long times. We map out the steady-state phase diagram using a cluster mean-field approach and characterize the dynamics with
stochastic tensor-network methods. Within the bistable phase we identify signatures of dynamical heterogeneity in both the local magnetization and the
entanglement dynamics. This highlights how competing
quantum fluctuations and classical kinetic constraints shape the relaxation dynamics and the phase structure of many-body systems.
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All authors Pietro Brighi, Gianluca Frazzei, Igor Lesanovsky, Juan P. Garrahan, Alberto Biella
General Relativity and Quantum Cosmology
Towards solving General Relativity with Physics-Informed Neural Networks
Juan A. Carretero, Jorge F. Urbán, Fernando Abalos et al. (+4 more)
Physics-Informed Neural Networks (PINNs) are a machine-learning framework for approximating solutions to systems of partial differential equations by constraining neural networks to satisfy the underlying physical laws. The resulting continuous representation does not require a predefined computational mesh and can be evaluated at arbitrary points within the training domain. In this work, we investigate the application of PINNs to Einstein's equations of General Relativity. We discuss the mathematical formulation, network architectures, loss functions, and training strategies used to obtain accurate spacetime solutions, and demonstrate the approach through a series of standard
benchmarks from Numerical Relativity. We then extend the method to a more astrophysical setting by considering the dynamical
evolution of an isolated solitonic
boson star. Our simulations show that a PINN operating directly in three-dimensional Cartesian coordinates can reproduce the
equilibrium structure of a highly compact
boson star and recover its characteristic radial oscillation frequencies. These results establish PINNs as a viable complementary framework for solving coupled matter-Einstein equations and exploring alternative formulations in numerical relativity.
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All authors Juan A. Carretero, Jorge F. Urbán, Fernando Abalos, Joan Massó, Oscar A. Reula, Jose A. Pons, Carlos Palenzuela
High Energy Astrophysical Phenomena
Cosmic-neighbor-associated distances to VHE and candidate VHE BL Lacs via SDSS photometric redshifts
Karri I. I. Koljonen and Elina Lindfors
BL Lac objects have distances that are difficult to estimate because their optical spectra rarely show identifiable emission or absorption lines. We present a method to constrain BL Lac distances by associating them with their
cosmic neighborhoods (local overdensities in the
cosmic web) identified in optical fields. Distances to
galaxies in these neighborhoods are estimated using the Sloan Digital Sky Survey (SDSS) photometric
redshifts. Using
cosmic-neighborhood associations previously established from multi-object spectroscopy and BL Lacs with spectroscopically measured
redshifts as control samples, we find that the
redshifts of the associated neighborhoods can be recovered with an accuracy of $\Delta z \sim 0.02-0.04$. When multiple candidate neighborhoods are present in the field, we rank the candidate associations using a central-location criterion. In 50% of cases, the BL Lac is associated with the correct neighborhood. We provide distance estimates for BL Lac objects without secure
redshift measurements, focusing on sources detected at very high energies (VHE; $E>100$,GeV) and on candidate VHE emitters. Combining intervening absorption systems, host-
galaxy imaging, $\gamma$-ray constraints, and our SDSS group-association method, we propose likely
redshifts for TXS 0141$+$268 ($z\sim0.93-0.95$), PKS 0735$+$178 ($z=0.64$), 3FHL J0905.5$+$1357 ($z=0.644$), B2 0912$+$29 ($z = 0.53$), 3FHL J1120.8$+$4212 ($z=0.363$), BZB J1243$+$3627 ($z=0.485$), 3FHL J1253.1$+$5300 ($z=0.664$), and RX J2156.0$+$1818 ($z=0.635$). Finally, we discuss how forthcoming narrow-band photometric-
redshift surveys can improve blazar distance estimates via group-association techniques.
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Quantum Physics
Exponential strong converse for blind quantum data compression
Kohdai Kuroiwa
We establish exponential strong converse
theorems for blind
quantum data compression of finite-dimensional mixed-state sources, with and without
entanglement assistance. Blind compression is a fundamental
quantum information processing task in which the sender aims to transmit
quantum states without direct access to the classical label. Strong converse is a notable aspect of data compression: the accuracy of the compression abruptly drops down to zero once the compression rate goes below a threshold. Strong converses for data compression have been established for pure-state sources; however, for mixed-state sources, the optimal compression rate is determined by a structural decomposition of
quantum states and can change substantially under small perturbations. This sensitivity makes it difficult to quantitatively analyze the trade-off between compression rate and error. Despite recent progress, whether a strong converse holds at the optimal rate has remained unresolved in general. In this work, we resolve this question affirmatively. For unassisted compression, we show that at every rate below the optimum, the accuracy decays exponentially with the block length for general mixed-state sources without restrictions on protocols. We also prove exponential strong converse for blind compression with unlimited
entanglement assistance at its optimal rate. Combining the two strong converse bounds yields exponential decay at every compression-
entanglement rate pair outside the complete achievable rate region. Our proof introduces a new overlap quantity based on the structure of
quantum states; this quantity connects preservation of the source information to the dimension of the transmitted system. We expect that this approach provides useful tools for converse analyses of other
quantum information-processing tasks involving mixed states.
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Astrophysics of Galaxies
Learning Gaia: A Generative Model Trained on the Gaia Data Release 3 Source Catalog
John Soltis
I train a conditional flow matching model on the positions, photometry, and astrometry of $\sim$ 579 million sources from the
Gaia Data Release 3 Source Catalog. Using a probabilistic masking scheme during training, I develop a model capable of generating mock
Gaia catalog sources with and without partial measurements of real
Gaia sources. The model can produce coarse-grained mock
Gaia Source Catalogs that reproduce the Milky Way disk and Magellanic Clouds, and can impute photometric and kinematic information. The model fails to reproduce small, distinct subpopulations like $\omega$ Centauri. This model is a necessary step towards a foundation model trained on the entirety of
Gaia data products, and provides a blueprint for future work with the upcoming
Gaia Data Release 4.
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Physics and Society
Multi-agent discussion gains less when dissent is withheld
Chand Sahil Mansuri, Xin Wang, Mengying Li et al. (+4 more)
Multi-
agent systems of LLMs add discussion to majority voting and are therefore expected to be more capable. However, empirical reports conflict on whether discussion improves accuracy or leads to an incorrect consensus. Here, we introduce a parsimonious model that explains when discussion improves accuracy and when it ends in an incorrect consensus, built from four behaviors repeatedly observed in LLM
agents: (1) withholding dissent, (2) internalizing a stated answer, (3) reconsidering after seeing dissent, and (4) correcting toward the correct answer. The model shows that discussion can overturn an incorrect initial majority only when the withholding rate $c$ is below a critical rate $c^* = \gamma/(\gamma + a)$, set by the net correction rate $\gamma$ and the internalization rate $a$. We estimate these rates from conversation logs with a
Bayesian method and place LLM teams relative to $c^*$. As the model predicts, the gain from discussion shrinks as withholding rises, across LLMs and on a hidden profile
benchmark, HiddenBench, and MedEInst. Instructing
agents not to withhold dissent increases this gain. Turning
reasoning off also increases the gain, because
reasoning raises the internalization rate $a$ and keeps
agents from reconsidering a minority answer. These findings reconcile the conflicting reports and identify when discussion outperforms majority voting.
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All authors Chand Sahil Mansuri, Xin Wang, Mengying Li, Bryan Acton, Rory Eckardt, Dhaval Patel, Sadamori Kojaku
High Energy Astrophysical Phenomena
Revealing the accretion disc structure in Changing State AGN: NGC1566
Huimei Wang, Chris Done, Riccardo Middei et al. (+1 more)
NGC1566 is a low mass ($\sim 6\times 10^6M_\odot$) Active
Galactic Nuclei (AGN) with unusual large amplitude variabilty in its
accretion flow. In the optical it cycles between recurring short bright episodes with strong blue/UV continuum and clear broad line emission, and a much weaker persistent level without strong broad lines, making it a repeating changing-state (CS) AGN. We re-analyse the intensive optical/UV and X-ray monitoring during the 2018 bright
flare, showing for the first time the corresponding
evolution of the (host
galaxy subtracted) optical/UV AGN spectrum as well as the X-ray emission. As seen in other CS-AGN, the strongest spectral
evolution is in a UV/soft X-ray component which likely disappears below $0.01L_{\rm Edd}$ while the hot corona and a redder optical/UV component show weaker variability. We show that the red optical emission is likely a composite of the intrinsic and reprocessed emission from the outer disc, together with diffuse continuum from the BLR, and discuss the different signatures predicted by this for continuum reverberation across the changing-state event. The historical lightcurves show repeated changing-state events tied to unusually large amplitude discrete
flares in the lightcurve. While these do not appear to be periodic, the behaviour does support previous suggestions that the
accretion flow is repeatedly perturbed, perhaps by an intermediate mass black hole companion.
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All authors Huimei Wang, Chris Done, Riccardo Middei, Xue-Bing Wu
Instrumentation and Methods for Astrophysics
An X-ray Extremely wide-field Spectroscopic Surveyor (XESS, or "chess")
W. P. Maksym, M. Ulmer, S. Friedrich et al. (+20 more)
We propose an X-ray observatory, the X-ray Extremely wide-field Spectroscopic Surveyor (XESS, pronounced "Chess") to bring high energy resolution X-ray spectroscopy into the era of synoptic surveys and of time domain and multi-messenger astrophysics (TDAMM). Such an observatory is optimally suited to addressing key elements of the 2020 Decadal Survey on Astronomy and Astrophysics.
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All authors W. P. Maksym, M. Ulmer, S. Friedrich, F. Tombesi, R. Arcodia, S. P. Singam, S. Bongiorno, N. Thomas, M. Elvis, Ming Sun, John ZuHone, M. Lynne Saade, Philip Kaaret, Doug Swartz, Erin Hicks, Ming-Yi Lin, Pallavi Patil, Jimmy Irwin, Shrabani Kumar, Kirtan Dixit, Sudip Chakraborty, Andrea Gnarini, Steven Ehlert
Solar and Stellar Astrophysics
Surveying for Close Binaries among Lithium-rich Giants
Jesús Torres, Sebastián Vilaza-Dallago, Julio Chanamé et al. (+1 more)
One of the possible scenarios usually considered to explain the existence of low-mass red
giants with anomalously high lithium (Li) abundances requires the interaction with a close binary companion. If dominant, this enrichment channel predicts a significantly enhanced binary fraction among Li-rich
giants relative to Li-normal ones. We aim to constrain the binary interaction hypothesis by using multi-epoch radial velocities (RVs) to measure the close binary fraction of a statistically robust sample of Li-rich
giants. We are surveying both red clump (RC) and first ascent red
giant (RGB) targets, which allows us to examine potential differences in the binary fraction as a function of evolutionary stage. We are monitoring 70 targets (40 RC and 30 RGB, all Li-rich) using ESPRESSO at the VLT, 57 of which (32 RC + 25 RGB) already have 4 or more visits over a $\sim$7 month baseline; the analysis in this paper is based on the latter. For the targets with RV variation larger than that expected for intrinsic jitter, we use a Monte Carlo analysis to estimate the probability that the observed RV variation is due to a
stellar ($P_{SB}$) or sub-
stellar ($P_{SS}$) companion. Discounting the 38 targets consistent with
stellar jitter, we are left with 11 RC and 8 RGB
stars (34% and 32% of the respective sub-samples) with RV variability consistent with the presence of a close companion with an orbital period shorter than 3000 days. Of these 19, 3 can be confirmed as
stellar-mass companions. The distributions of $P_{SB}$ and $P_{SS}$ are statistically indistinguishable between the RC and RGB samples. We thus find no evidence so far in our current data for a binary fraction for Li-rich
giants (in either evolutionary stage) larger than that expected for a Li-normal population. Extending the RV baseline to probe longer orbital periods will be important to keep exploring the plausibility of this scenario.
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All authors Jesús Torres, Sebastián Vilaza-Dallago, Julio Chanamé, Rafael Brahm
Quantum Physics
When Symmetry Suppresses Magic
A. de Oliveira Junior, Jake Xuereb, Rafael A. Macêdo et al. (+2 more)
Nonstabilizerness is a critical resource for
quantum advantage, but evaluating it, especially for mixed states, requires superexponentially many samples in system size, making the problem NP-hard. While
symmetries are known to reduce this complexity, it is unclear whether they also restrict the amount of magic. In this work, we provide an explicit example of such a
symmetry by proving that the Robustness of Magic (RoM) for N-
qubit X-states is at most $\sqrt{3}$. Leveraging this
symmetry constraint, we introduce a computationally efficient method to lower-bound the RoM of arbitrary many-body states, demonstrating its utility on the ground states of a
spin-1/2
Hamiltonian with system sizes well beyond the reach of exact evaluation. Furthermore, for
Hamiltonians whose
equilibrium states are X-states, we analytically derive the critical temperature at which magic emerges. Our work shows why certain
symmetries constrain magic while others do not, provides a scalable lower-bounding method, and identifies a nontrivial regime where many-body nonstabilizerness is analytically solvable.
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All authors A. de Oliveira Junior, Jake Xuereb, Rafael A. Macêdo, Jonatan Bohr Brask, Rafael Chaves
High Energy Physics (Theory)
Energy Transmission Across Holographic Conformal Interfaces in General Dimensions
Igal Arav, Theodore Bertrand, Shira Chapman et al. (+2 more)
Energy transport across conformal interfaces is universal in two spacetime dimensions, but its higher-dimensional counterpart has remained largely unexplored. In higher dimensions, scattering can depend on additional kinematic data, such as the angle of incidence, and conformal
symmetry is far less restrictive. We use gravitational holography to study this problem. For a broad class of AdS$_d$-sliced domain-wall geometries, we derive a closed-form expression for the energy transmission coefficient in terms of the bulk warp factor. Our formula reproduces known two-dimensional
holographic results and extends them to arbitrary dimension. Within this class, we establish different aspects of higher-dimensional universality. In particular, we show that the transmission is independent of the incidence angle and of the profile of the incident perturbation. We also derive bounds on transmission controlled by central-charge-like quantities characterizing the number of degrees of freedom of the theories on the two sides of the interface. This provides the first explicit result for reflection and transmission across conformal interfaces in higher dimensions, where no CFT-based results are currently available.
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All authors Igal Arav, Theodore Bertrand, Shira Chapman, Giuseppe Policastro, Sebastian Waeber
Mesoscale and Nanoscale Physics
Hidden Angular Momentum Loop Currents in Symmetric Crystals
Rule Yi, Vincent P. Flynn and Benedetta Flebus
Loop-current order has been invoked to explain unconventional electronic phases, with the
crystal lattice usually regarded as a passive host for the underlying collective dynamics. Here we show that circulating currents can originate in the
lattice itself, sustained by
quantum and thermal fluctuations. We develop a microscopic description of angular momentum exchange that separates transfer between sites from crystalline restoring torques and reveals how circulation can emerge in a
symmetry-preserving
equilibrium state. In a two-dimensional elastic
lattice preserving time-reversal, inversion, and fourfold rotational
symmetries, we uncover opposite current loops on neighboring plaquettes while the mean angular momentum vanishes at every site. These currents are sustained by zero-point fluctuations in the
phonon vacuum and persist at finite temperature. We trace their origin to directional elastic interactions in locally
symmetry-lowered environments, with the higher
crystal symmetry organizing the resulting currents into a compensated pattern of circulation. Our results extend the physics of
equilibrium loop currents to
lattice dynamics, revealing that elastic geometry can organize fluctuations into persistent angular momentum circulation without electronic or
magnetic order, external driving, or spontaneous
symmetry breaking.
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High Energy Physics (Phenomenology)
Constraints on Complex Electroweak WIMPs from Solar Capture
Juan P. Luengas, Maxim Pospelov and Harikrishnan Ramani
One of the most convincing realizations of particle dark matter is provided by models based on electroweak multiplets. The lightest neutral state of such a multiplet can be a stable Majorana
fermion or a real scalar, and its phenomenology is governed by two parameters: the dark matter mass and the mass splitting $\{m_\chi,\delta\}$. The sub-MeV range for $\delta$ is particularly important as it allows for a large inelastic scattering cross section. In this paper, we analyze
solar capture, energy loss, and annihilation of scalar and fermionic electroweak multiplet dark matter, generalizing earlier results for the Higgsino to other representations. We find that, while the case of a doublet is somewhat special, higher representations behave in a self-similar way. For the higher multiplets, IceCube results constrain the splitting to $\delta \gtrsim 350$ keV for all dark matter masses up to $100$ TeV. Assuming thermal freeze-out and a Standard
Halo Model velocity distribution, this rules out most models of electroweak dark matter as a possible origin of the single high-
recoil event reported by the LZ collaboration. We also show that a high-velocity tail in the dark matter distribution, such as that induced by the Large Magellanic Cloud, raises the splitting preferred by the LZ event above the
solar bounds for many of the multiplets.
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Earth and Planetary Astrophysics
An Infant Sub-Saturn in Scorpius-Centaurus
Gurmeher Kathuria, Luke G. Bouma, Andrew W. Boyle et al. (+25 more)
We report the discovery and validation of TIC 88297141 Ab, a transiting
planet orbiting a pre-main-sequence M
dwarf (0.31
solar masses, 0.74
solar radii) in the Scorpius-Centaurus OB association. Group membership implies an age of $15.6 \pm 1.6$ Myr, supported by lithium and isochrone age-dating. We detected the TESS transits using a custom pipeline designed for variable
stars and used ground-based photometry (LCO/Swope and LCOGT/Sinistro) to confirm the on-target nature of the signal. Our global fit of the transits and
stellar activity gives an orbital period of 4.64 days and a
planet radius of $7.21 \pm 0.32$ Earth radii (0.64 Jupiter radii). The
star has a comoving M-
dwarf companion (0.4
solar radii) at a projected separation of $260$ au; speckle imaging (Gemini-S/Zorro) reveals no additional
stellar companions, and radial velocities from Magellan/PFS are consistent with
stellar activity, giving $M_p \sin i < 4.7$ Jupiter masses at $2\sigma$. A statistical validation analysis yields a false positive probability of $10^{-5}$, validating the
planet. A mass measurement will determine whether TIC 88297141 Ab is a low-density super-puff, like other comparably sized
planets at these ages, or an unusually massive
planet for its radius.
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All authors Gurmeher Kathuria, Luke G. Bouma, Andrew W. Boyle, Roberto Tejada Arevalo, Andrew W. Mann, Nidia Morrell, Karen A. Collins, R. Paul Butler, Stephen A. Shectman, Johanna Teske, Jeffrey D. Crane, Shreyas Vissapragada, Madeleine Mckenzie, Khalid Barkaoui, Norio Narita, Akihiko Fukui, Jerome P. De Leon, Toshi Suganuma, Madyson G. Barber, Francis P. Wilkin, Victoria Zaledonis, Sophia Garcia-Gallet, Glauk Hizmo, Steve B. Howell, David R. Ciardi, Colin Littlefield, Sarah Deveny, Douglas A. Caldwell
High Energy Physics (Phenomenology)
How collective modes terminate in the dispersion relation of neutrino plasmas
Damiano F. G. Fiorillo
Neutrino plasmas support
flavor waves, collective oscillations of
flavor, that
neutrinos can resonantly emit or absorb when they fulfill the Cherenkov condition. For massless
neutrinos, this condition leads to singular features in the dispersion relation: Landau-damped modes, for example, disappear abruptly as their phase velocity approaches the speed of light. We investigate how these singularities change when nonzero
neutrino masses introduce a spread in velocities. We classify singular behavior of the frequency as a function of wavevector into i) degeneracy points, where two modes merge, and ii) abrupt mode termination, when the frequency approaches a branch cut of the
flavor dielectric function. For each class, we derive a local expansion and determine where such behavior can occur. Degeneracy points, frequently encountered in axially symmetric dispersion relations in the fast limit, are not generic. Nonzero
neutrino masses lift the degeneracy along the
symmetry axis; in three-dimensional wavevector space, there might still be degeneracy lines, not necessarily intersecting the
symmetry axis. Abrupt mode termination, instead, persists generically, except for special energy distributions which are entire functions. As a byproduct of this study, we show that a collisionless
plasma with a Lorentzian
neutrino-frequency distribution is exactly equivalent to a monochromatic one with an effective collision rate. Approximating a general frequency distribution by a sum of Lorentzians therefore substantially simplifies the dispersion relation.
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High Energy Physics (Theory)
Holographic Krylov spread complexity for a confining multi-charge AdS soliton
Dimitrios Chatzis, Madison Hammond, Ricardo T. Santamaria et al. (+1 more)
We study
holographic spread complexity for a Type IIB solution dual to a deformation of $\mathcal{N} = 4$ SYM that flows to a confining (2+1)-dimensional supersymmetric theory in the IR. We use the proposal that relates the rate of change of spread complexity of local operators with the proper momentum of an infalling probe particle in the bulk. We analyse two cases: a probe particle falling radially and a probe falling radially while rotating with conserved angular momentum. We elaborate on how to define the proper coordinate in the presence of a conserved Noether charge using the Routhian. The trajectories for the probes were studied numerically, revealing an oscillatory behaviour of the complexity.
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All authors Dimitrios Chatzis, Madison Hammond, Ricardo T. Santamaria, Jonathan Whittle