Nuclear Theory
Bridging Ab Initio Symmetries and Global Nuclear Masses with Interpretable Neural Networks
Phong Dang, Evander Espinoza, Xiaoliang Wan et al. (+6 more)
Ab initio theory establishes Wigner's SU(4) and Elliott's SU(3) as dominant
symmetries of the
nuclear force in light and intermediate-mass
nuclei. Previous work shows the relevance of the former
symmetry for
nuclear binding, whether the latter organizes binding remains elusive. We probe whether both these
symmetries organize
nuclear masses, aiming at physical insights through interpretable models and predictive capability. From the SU(3) and SU(4) Casimirs we build 3 neural-network models. Two are conventional, a feature-informed NN (FINN) and a Gaussian variant (GINN) with predictive spread, while Wigner-informed network (WINN) is a new design constraining the mass formula to be linear in the operators, learning their (N,Z)-dependent couplings, so that the model is intrinsically explainable. All are trained on AME2016 subtracted by the
liquid drop model at 4 data fractions and validated on
nuclei new to AME2020, with extrapolation benchmarked against HFB-26 and r-process. The Casimir features carry binding information far beyond the bulk, and SHAP analysis suggests the quadratic SU(4) Casimir as the leading contributor to the residual binding. The WINN yields the best performance, reaching a 0.412 MeV validation error and competitive with state-of-the-art models, and importantly, when trained on the sparsest
dataset it outperforms the other NNs trained on the densest. Off the known chart its masses track HFB-26 as closely as WS3 and reproduce the
solar abundance peaks of a
neutron-
star-merger simulation. The WINN's coupling fields reveal an enhanced even-SU(4) contribution toward the
neutron dripline, hinting at restoration of Wigner's
symmetry. The SU(4) and SU(3) structures reach beyond individual
nuclei to organize binding, and
embedding symmetry-preserving operators directly in a domain-informed interpretable architecture yields a physically transparent model less hungry for data.
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All authors Phong Dang, Evander Espinoza, Xiaoliang Wan, Michela Negro, Jerry P. Draayer, Feng Pan, Tomas Dytrych, Daniel Langr, David Kekejian
High Energy Astrophysical Phenomena
JWST observations support the jittering-jets explosion mechanism (JJEM) for the core-collapse supernova remnant SNR 0540-69.3
Dmitry Shishkin and Noam Soker
We examine published JWST observations of the core-collapse
supernova (CCSN) remnant SNR 0540-69.3 and identify a point-symmetric morphology in its inner ejecta. Within the framework of the jittering jets explosion mechanism (JJEM), we interpret this morphology as evidence that the ejecta were shaped by two, and likely three or more, pairs of jets during the explosion process. Both visual inspection and a recently developed quantitative
symmetry-identification method for astrophysical imaging reveal an approximate rotational
symmetry between the northeastern redshifted ejecta and the southwestern blueshifted ejecta. Each side contains clumps (
knots) surrounding a previously identified cavity, with the best quantitative correspondence obtained for a rotation of 189{\deg}. We further identify a
symmetry center that is offset from the current
pulsar position, strengthening an earlier claim for a
pulsar kick. We interpret the pair of cavities and their surrounding clumpy structures as having been shaped by multiple jet-launching episodes. In addition, we identify a pair of opposing nozzles at a large angle to the cavities, which we attribute to another jet pair. Guided by the similarities to point-symmetric planetary nebulae shaped by jets and by recent three-dimensional hydrodynamical simulations of the JJEM, we conclude that the inner ejecta were shaped by at least three jet pairs launched by the
neutron star after it acquired its kick velocity, consistent with the JJEM.
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Nuclear Theory
QCD critical surface from constant entropy contours
Hitansh Shah, Tristan Gyure, Anabella Leon et al. (+4 more)
We provide the first mapping of the critical surface in (2+1)-
flavor QCD in the full $(T,\mu_B,\mu_Q,\mu_S)$ space, anchored on
lattice QCD results at vanishing chemical potentials and obtained within an expansion along contours of constant
entropy density. In the pure $\mu_B$ direction, this framework yields a critical point at $(T_c,\mu_{B,c}) \simeq (114,\, 602)$ MeV. Here we extend the construction to arbitrary directions in the three-dimensional chemical-potential space, parametrized by spherical coordinates $(\mu,\theta,\varphi)$, with the radial expansion truncated at $\mathcal{O}(\mu^2)$. The resulting two-dimensional surface carries a direction-dependent critical temperature $T_c(\theta,\varphi)$ and baryochemical potential $\mu_{B,c}(\theta,\varphi)$, which quantify the shift of the critical point relative to the pure $\mu_B$ direction. We find that $\mu_{B,c}$ increases by 40-100 MeV along the approximately strangeness neutral direction [$\mu_S \approx (0.15$–$0.33)\, \mu_B$, $\mu_Q \approx 0$] relevant for heavy-ion collisions, while the critical temperature stays essentially unchanged. In the charge-neutral, weak-
equilibrium direction~[$\mu_Q \approx -(0.05$–$0.1) \,\mu_B$, $\mu_S = 0$] relevant for
neutron star mergers, the critical point, and the associated first-order phase transition, remain present at essentially the same location in the $(T,\mu_B)$ plane. We find no evidence for a critical point at large isospin densities, $|\mu_Q| / \mu_B \gtrsim 1$, relevant for
cosmic trajectories in the early Universe, nor along the pure electric-charge or strangeness directions, at least outside the regions where pion or kaon condensation may occur.
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All authors Hitansh Shah, Tristan Gyure, Anabella Leon, Francesco Di Clemente, Mauricio Hippert, Claudia Ratti, Volodymyr Vovchenko
High Energy Physics (Theory)
Surface Water Wave Scattering and the Hydrotope
Nima Arkani-Hamed, Francesco Calisto, Nail Ussembayev et al. (+2 more)
We study the classical tree-level scattering amplitudes of deep-water surface
gravity waves using the methods of high-energy physics. For scattering in one horizontal dimension and in the two-negative-wavenumber sector we obtain a closed formula for $n$-wave scattering. Up to a kinematic prefactor, the amplitude is the volume of a classic polytope – a box sliced by a hyperplane, which we dub the hydrotope, whose purpose in life is simply to organize the sign patterns of the "chambers" characterizing all the different regions of the two-minus kinematic space. The general formula was discovered by Claude Opus 4.6 working under our guidance, beginning with our earlier discovery of a one-term expression valid in the "simplest" kinematic chamber. Our results resolve the puzzle raised by Y.V. Lvov's 1997 computation of the five-wave amplitudes, unifying and extending it to all multiplicities.
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All authors Nima Arkani-Hamed, Francesco Calisto, Nail Ussembayev, W. Wayne Zhao, Zihan Zhou
High Energy Physics (Phenomenology)
Revealing precision bounds on neutrino oscillation parameters with quantum estimation theory
Jihong Huang, Tommy Ohlsson, Sampsa Vihonen et al. (+1 more)
Quantum estimation theory provides ultimate precision bounds on parameter estimation, independent of experimental setups. In this article, we apply this theoretical framework to
neutrino oscillations, aiming to clarify some subtle issues and reveal the maximum achievable precision of oscillation parameters. First, taking the example of two-
flavor oscillations, we clarify how the
quantum Fisher information (QFI) depends on the choice of bases when the basis transformation itself involves the parameters in question. Then, for three-
flavor oscillations, we compute the QFI
matrix for electron and
muon neutrino states in the
flavor basis and derive analytical expressions and numerical results for both diagonal and off-diagonal elements. The implications of off-diagonal correlations for multiparameter estimation are discussed, and the
quantum Cramér-Rao bounds on the precision of oscillation parameters for typical reactor and long-baseline accelerator
neutrino experiments are obtained. Our results establish a theoretical
benchmark for the ultimate precision achievable in future
neutrino oscillation experiments.
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All authors Jihong Huang, Tommy Ohlsson, Sampsa Vihonen, Shun Zhou
High Energy Physics (Phenomenology)
Neutrino oscillation data and a pseudo-Dirac heavy neutral lepton
Jan Hajer
Symmetry-protected seesaw models can accommodate light-
neutrino oscillation data while keeping heavy neutral
leptons (HNLs) within
collider reach. In these models, the smallness of the light-
neutrino masses is protected by an approximate
lepton number (LN)-like
symmetry that is broken only by small parameters. We study the minimal scenario in which the new states form one pseudo-Dirac HNL pair. The exact LN-conserving Dirac limit is diagonalised without expanding in the active-sterile mixing, and the small LN-violating entries are then included perturbatively. This yields a
symmetry-protected flavour reconstruction of the active-heavy interaction
matrix. The rank-two light-
neutrino mass
matrix fixes the normalised active-flavour direction, while the remaining high-energy information is a single complex light-heavy amplitude whose phase defines a CP-odd light-heavy invariant. For the normalised leading active-heavy interaction weights, this amplitude and the heavy-sector rotation cancel, leaving an ellipse in the flavour simplex determined by light-
neutrino oscillation data and the Majorana phase. We also identify how the linear LN-violating terms enter coherent heavy-
neutrino oscillations and the neutrinoless double beta effective mass.
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Mathematical Physics
Which Saddles Contribute? The South-East Rule for Multidimensional Integrals
Inês Aniceto, Job Feldbrugge and Christopher J. Howls
In this paper, we introduce and demonstrate a simple
geometric algorithm to determine which critical points, both complex as well as real, contribute to the asymptotic evaluation of multiple integrals with exponential integrands of the form $e^{ikf(\boldsymbol{x})}$ over $\mathbb R^d$, for finite $d\ge 1$ and $f$ is analytic. In so doing, the
algorithm removes the need to compute the flows of $-\text{Re} (i\nabla f)$ in $\mathbb C^d$ that is required to identify such relevant critical points in Picard-Lefschetz approaches to the derivation of such asymptotic expansions. By contrast, our
algorithm relies on the combination of three simple features: the values of $f$ at all the critical points plotted in the complex Borel plane, the concept of adjacency between such points derived from algebraic resurgence/hyperasymptotic approaches and the new result here of a
geometric "South-East" rule. The
algorithm incorporates functions $f$ that remain bounded or unbounded on $\mathbb R^d$. We illustrate this new approach with both pedagogical and advanced examples, and draw conclusions as to its importance for resolving issues associated with Wick rotations and its implications for path integrals. This is a significant step towards a systematic way of identifying instanton contributions in real-time path integrals.
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Quantum Physics
Efficient Approximation of the Wigner Kernel in Phase-Space Quantum Mechanics
Mehran Attar, Bassant Selim and Jean Michel Sellier
The Signed Particle Formulation provides a particle-based interpretation of
quantum mechanics in phase space, where
quantum dynamics are represented through the creation and
evolution of signed particles. A central computational challenge in this framework is the evaluation of the Wigner kernel, which generally involves highly oscillatory integrals and can become computationally demanding in time-dependent simulations. This paper proposes an analytical approximation of the Wigner kernel for one-dimensional single body
quantum systems by exploiting a series-based representation of the potential function. The resulting expression provides an efficient way to approximate the Wigner kernel and the associated Gamma function, which governs the particle-generation process in the Signed Particle Formulation framework. The proposed approximation is evaluated for several Gaussian-based potential profiles, including single, double, triple, and quadruple Gaussian potentials. Numerical comparisons between the approximated and directly computed Wigner kernels and Gamma functions show that the proposed method captures the main behavior of the exact quantities while significantly reducing the computational cost. These results indicate that the proposed approximation can serve as an efficient computational component for scalable Signed Particle Formulation based
quantum simulations.
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High Energy Astrophysical Phenomena
Early Optical Follow-up of Gamma-Ray Bursts: The Critical Role of Robotic Telescopes
Rahul Gupta, Judith Racusin, Gor Oganesyan et al. (+26 more)
Gamma-ray bursts (GRBs) are the most luminous electromagnetic explosions in the Universe, and offer unique laboratories for studying relativistic jets, compact-object formation, particle acceleration, and the high-
redshift Universe. The early optical emission of GRBs, particularly within seconds to minutes after the burst, carries crucial information about the central engine, jet magnetization, bulk Lorentz factor, and circumburst environment. We present a comprehensive review of the early optical phenomenology of GRBs and the essential role played by ground-based robotic optical
telescopes to observe the fleeting early-time phenomena through rapid, automated responses to real-time GRB alerts and high-cadence photometry. We examine the key early optical features of GRBs, including
prompt optical emission coincident with the $\gamma$-ray phase, bright reverse shock optical flashes, the onset of external forward shock afterglow, and superimposed optical
flares, plateaus, and discuss the diagnostic power of each in constraining jet physics. We discuss the physical mechanisms underlying these phenomena and their implications for GRB physics (e.g., estimating the initial Lorentz factor $\Gamma_0$, magnetization, and the density profile). Early optical observations have constrained the initial bulk Lorentz factor $\Gamma_0 \sim 100$–$1000$, weak-to-moderate ejecta magnetization for events with prominent reverse shocks, the circumburst density profile, and the geometry of the
magnetic field in the ejecta through polarimetry. We also provide the technical capabilities and landmark contributions of major robotic facilities, and discuss future prospects in the era of SVOM, Einstein Probe, Rubin/LSST, ULTRASAT, TeV observatories, and multi-messenger alerts.
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All authors Rahul Gupta, Judith Racusin, Gor Oganesyan, Ramandeep Gill, Sergey Karpov, Samantha R. Oates, Maria Gritsevich, Alberto J. Castro-Tirado, Vladimir Lipunov, Benjamin P. Gompertz, Maria Giovanna Dainotti, S. Bradley Cenko, Bing Zhang, Toktarkhan Komesh, Martin Jelínek, Stéphane Basa, Takanori Sakamoto, Carl W. Akerlof, Antonio Martin Carrillo, Sam Shilling, Ryan Seeb, Shashi B. Pandey, Varun Bhalerao, M. D. Caballero-Garcia, Ivan Panchenko, Pavel Balanutsa, Artem Kuznetsov, Kirill Zhirkov, Natalia Tyurina
Atmospheric and Oceanic Physics
A Two-Step Ensemble Score Filter for Data Assimilation in Partially Observed Systems
Zixiang Xiong, Feng Bao, Hristo G. Chipilski et al. (+3 more)
Data assimilation blends model forecasts with observations to estimate the evolving state of complex dynamical systems, but sparse observing networks remain challenging because unobserved state variables are not directly constrained by observations. In this work, we introduce the Ensemble Score Filter with Linear Regression (EnSF-LR), a two-step filtering method for partially observed nonlinear systems. At each analysis time, EnSF-LR first applies the Ensemble Score Filter (EnSF) to update the observed state components using a nonlinear score-based analysis update. It then computes the resulting observed-state analysis increments and maps these corrections to the unobserved components through the ensemble-based prior covariance
matrix. The latter amounts to the same linear regression mechanism used by Ensemble Kalman Filters (EnKFs). We evaluate EnSF-LR using the Lorenz-63 and 40-dimensional Lorenz-96 systems with sparse linear and nonlinear observations. The method is compared with the original EnSF and with the classical
stochastic EnKF. In the linear-observation experiments, EnSF-LR produces accuracy comparable to the EnKF baseline while substantially reducing error relative to the original EnSF. In the nonlinear-observation experiments, EnSF-LR achieves lower full-state root-mean-square error than both the original EnSF and the EnKF reference. These results suggest that hybridizing score-based and EnKF analysis schemes provides an effective strategy for assimilating sparse and nonlinear observations.
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All authors Zixiang Xiong, Feng Bao, Hristo G. Chipilski, Siming Liang, Jingqiao Tang, Guannan Zhang
Mathematical Physics · Cross-listed from math.SP
Multi-parameter Perturbations of the Laplacian and Resonance Near a Simple Embedded Eigenvalue
Hemant Bansal, Alok Maharana and Lingaraj Sahu
This paper continues the study of resonance phenomena initiated in [3] for rank-one perturbations. We consider finite-rank multi-parameter perturbations $H_\alpha$ of the
Laplacian on \(L^2(\mathbb{R}^3)\) and establish Breit–Wigner-type asymptotics for the spectral density of $H_\alpha$ along the resonance $\lambda(\alpha)$ near a simple embedded
eigenvalue $\lambda_0$ of $H_a$ as $\alpha\to a$. We also obtain similar asymptotic behaviour for the scattering cross-section and the average time delay.
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Disordered Systems and Neural Networks
Classical versus quantum Anderson localization in disordered systems
Stefano Mossa, Giancarlo Ruocco and Walter Schirmacher
We investigate Anderson localization in three-dimensional disordered systems by comparing scalar classical waves with mass and force-constant disorder to electronic tight-binding models with diagonal and off-diagonal disorder. We show that the commonly employed mapping between classical-wave localization and the electronic Anderson model with diagonal disorder is not mathematically justified. Instead, the correct modulus-type formulation reveals that classical-wave systems constitute a distinct constrained disorder class, in which the acoustic sum rule correlates diagonal and off-diagonal
matrix elements and prevents any direct correspondence with the standard electronic disorder models. Within a unified
eigenvalue framework, we determine localization phase diagrams for all four disorder classes using complementary spectral, eigenvector, and level-statistics diagnostics. We find that classical-wave systems share a key qualitative feature with electronic off-diagonal disorder: localized states occur only near a band edge, while extended states persist in the central part of the spectrum even at strong disorder. At the same time, the acoustic sum rule produces localization
topologies that differ fundamentally from both diagonal- and off-diagonal-disorder electronic systems. In particular, for mass disorder we obtain a phase diagram that differs qualitatively from previous results based on the conventional potential-type approach and reveals an extended localized regime near the upper band edge. Our results establish a unified perspective on localization in
quantum and classical wave systems and provide new insight into the conditions under which Anderson localization may occur in three-dimensional photonic and acoustic media.
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Biological Physics
The Allee Effect in Compressible Flows
Jonathan Bauermann, Roberto Benzi, David R. Nelson et al. (+1 more)
Microbes in marine environments are often confined to thin near-surface layers while being advected by turbulent flows. Because such constrained advection generates an effectively compressible flow, reproduction and transport interact in a nontrivial way. Here, we focus on populations whose growth is governed by an Allee effect and show that sinks and sources, generated by the compressible flow, have dramatic consequences for the survival of such species. We derive analytical expressions for the carrying capacity as a function of the Allee strength in the limit of small and large Damköhler number, which measures the product of the large eddy turnover time and the organism growth rate. Numerical simulations reveal how these two limits connect. In the limit of small Damköhler number, we find a maximal Allee strength, set by the statistics of the compressible flow, that leads to species extinction in fully developed
turbulence.
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All authors Jonathan Bauermann, Roberto Benzi, David R. Nelson, Federico Toschi
High Energy Astrophysical Phenomena
Numerical model of fast electron energy deposition in interstellar molecular gas
Aleksandr Nesterenok
The energy deposition of fast electrons in interstellar molecular gas is considered. We use the rotationally resolved cross sections for electron-impact excitation of H$_2$ molecule that were calculated using the adiabatic-
nuclei molecular convergent close-coupling method. The initial electron energy distribution is assumed mono-energetic, and the differential equation for electron energy distribution is solved. We compare calculated energy deposition parameters with the results of similar studies in which the Monte Carlo approach was used. It is shown that about 11 per cent of the initial energy of fast electrons goes into direct ro-vibrational excitation of energy levels of H$_2$ molecule including pure rotational excitation in neutral molecular gas. About 7 per cent of initial electron energy goes into the excitation to $v=1$ vibrational state of H$_2$ molecule, most of this energy eventually converts into emission of transitions at near-infrared wavelengths. For ro-vibrational levels with $v \geq 3$, the electron-impact excitation to electronic states followed by downward radiative transitions to the ground electronic state is the dominant mechanism of excitation. The yields for excitation to vibrational states via radiative cascading from excited electronic states are found to be $1.5-2$ times higher than were obtained in previous studies.
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Earth and Planetary Astrophysics
Reflective-Sail Weak Stability Boundary Structure with the Locally Optimal Control Law
Shuyue Fu, Jinkai Zhang, Di Wu et al. (+2 more)
Escaping from the Earth is the first step of interplanetary transfers. Traditional ballistic escape trajectories in the Sun-Earth circular restricted three-body problem face limitations in relatively long time of flight and low
hyperbolic excess velocity. To augment the construction of escape trajectories from the Earth, this Note proposes the concept of reflective-sail weak stability boundary structures and accordingly constructs and analyzes escape trajectories from the Earth in the context of the Sun-Earth planar circular restricted three-body problem with a reflective sail. Using an ideal reflective sail, the locally optimal control law to maximize the time derivative of the Keplerian energy with respect to the Earth is adopted. Levi-Civita regularization about the Earth is derived to address the singularity caused by the Earth. The configurations of reflective-sail weak stability boundary structures are calculated to provide initial states for constructing escape trajectories and information about regions where escape is facilitated. Then, the escape trajectories using a reflective sail are constructed based on the proposed weak stability boundary structures. The escape performance, including time of flight and estimated
hyperbolic excess velocity, is analyzed. Comparison with ballistic escape trajectories in the Sun-Earth PCR3BP is also performed, indicating improved escape performance characterized by shorter time of flight and higher
hyperbolic excess velocity.
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All authors Shuyue Fu, Jinkai Zhang, Di Wu, Shengping Gong, Peng Shi
Astrophysics of Galaxies
When Jets Don't Quench: Near-Infrared H$_{2}$ in Star Forming Low-Excitation Radio Galaxies
Swetha Sankar, Andreea O. Petric, Debora Pelliccia et al. (+11 more)
We present new Gemini/GNIRS near-infrared spectroscopic observations of eight low-
redshift ($z < 0.1$) blue low-excitation
radio galaxies (BLERGs), a rare subset ($\sim 2.5\%$ of low-excitation
radio galaxies; LERGs) that complicate the classical jet-mode AGN picture by combining
radio activity with
star-forming, gas-rich hosts. These
star-forming BLERGs exhibit significant warm H$_2$ emission traced via ro-vibrational transitions at $T \sim 2000$–$4000$ K. We find that BLERGs span a broad range of mass-normalized warm H$_2$ luminosities ($L_{\rm H_2}/M_\star$), comparable to
radio-emitting early-type
galaxies, yet without a clear positive dependence on
radio power. Instead, the strongest H$_2$ emission preferentially occurs in morphologically disturbed and advanced-merger systems, while compact
radio sources ($\lesssim 20$ kpc) remain plausible sites of localized jet-ISM interaction. Together, these results suggest that merger-driven processes, including
tidal shocks, gas inflows, and disturbed interstellar medium conditions, are the dominant drivers of warm molecular gas excitation in BLERGs, although localized jet-driven heating may contribute in individual systems. The compact
radio morphologies, gas-rich hosts, and rarity of BLERGs are consistent with a short-lived evolutionary phase in which
radio AGN activity coexists with an interaction-driven, molecular-rich interstellar medium prior to the onset of large-scale maintenance-mode feedback. Spatially resolved spectroscopy and higher-resolution
radio imaging will be essential to disentangle the relative roles of mergers and jets in regulating the molecular gas of jet-mode AGN.
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All authors Swetha Sankar, Andreea O. Petric, Debora Pelliccia, Timothy M. Heckman, Reiner M. J. Janssen, Mark Lacy, Nicole P. H. Nesvadba, Kate Rowlands, Pallavi Patil, Brian C. Lemaux, Maya Skarbinski, Annie Giman, Justin A. Otter, Katherine Alatalo
Quantum Physics
Efficient targeting of arbitrary excited states with quantum inverse power iteration through filtering polynomials
Srushti Patil and Nina Glaser
In this work, we introduce a
quantum inverse power iteration (QIPI)
algorithm based on the
quantum singular value transformation (QSVT) to target arbitrary excited states. Given an energy shift $\omega$, QIPI prepares the target excited state by iteratively applying an approximation of the shifted inverse
Hamiltonian $(H-\omega I)^{-1}$ to a trial state. Prior
quantum inverse power approaches typically relied on
Fourier decompositions of the inverse
Hamiltonian, with numerical quadrature used to reconstruct the transformation, but such methods are highly sensitive to hyperparameter choices and have been observed to be numerically unstable, effectively restricting their use to ground-state preparation. To enable robust excited-state targeting, we investigate two alternative transformation techniques: a Chebyshev decomposition of the inverse (Cheb-inv) and an eigenstate filtering (EF) approach based on QSVT. We find that EF-based QIPI is substantially more robust than Cheb-inv and other decomposition-based approaches due to the
symmetry of the applied filtering
polynomial, avoiding divergence with respect to the choice of $\omega$ and efficiently suppressing off-target eigenstates even in closely spaced spectra. Numerical simulations for molecular
Hamiltonians of H$_2$, LiH, and BeH$_2$ show improved convergence and enhanced access to higher excited states relative to other
quantum power methods. Assuming standard oracle access to the
Hamiltonian, we further provide logical resource estimates in fault-tolerant settings in terms of T gate counts, and conclude that QIPI can achieve high target state amplification with modest
polynomial degrees, thereby making it a promising candidate for scalable excited-state preparation in fault-tolerant
quantum chemistry applications.
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General Relativity and Quantum Cosmology
Nonlinear stability of subextremal Kerr black holes
Peter Hintz
We settle the global nonlinear stability problem for the family of Kerr black holes in the full subextremal range: spacetimes evolving from initial data close to those of a subextremal Kerr black hole as solutions of the Einstein
vacuum equation ${\rm Ric}(g)=0$ settle down to a nearby member of the Kerr family at the rate $\mathcal{O}(t_*^{-2-\epsilon_{\mathcal K}})$ in spatially compact regions. For the initial data, we require $\mathcal{O}(r^{-1-\epsilon_0})$-decay for $\epsilon_0>0$ – more precisely, an arbitrary but finite expansion into terms $r^{-z}(\log r)^k$ where $z>1$, $k\in\mathbb{N}_0$, plus a remainder term with $\mathcal{O}(r^{-3-\epsilon_0})$-decay. We use a generalized wave map gauge modified using gauge source terms that lie in a suitable finite-dimensional space determined by the expansion of the initial data. Like the final black hole parameters (mass and angular momentum) and the gravitational wave tail, the gauge source terms are treated as unknowns in a nonlinear (Nash-Moser) iteration scheme. We work directly with the tensorial equation and in particular do not rely on reductions to scalar equations (except insofar as a reduction to the Teukolsky equation is used in the proof of linear mode stability). This paper relies on two companion papers by the author. The first one introduces a strong form of constraint damping in the full subextremal range, which we use in our formulation of the gauge-fixed Einstein equation as a black box. The second one provides tame estimates (albeit with weak decay) for forward solutions of a general class of wave-type equations, which we show here to include the linearizations of the gauge-fixed Einstein equation arising in our nonlinear iteration scheme; these estimates are the starting point for our detailed asymptotic analysis.
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Quantum Physics
Parameter-Efficient Continuous-Variable Photonic Quantum Neural Networks for Edge Quantum AI: Demonstration in Oral Cancer Detection
Akshay Bhagwan Sonawane, Sophie Choe and Lakshman Tamil
Early detection of oral cancer markedly improves clinical outcomes, yet specialized diagnostic tools remain scarce in low-resource settings. Smartphone-based screening is a scalable alternative but needs lightweight models that run within edge-hardware constraints. Hybrid classical-
quantum architectures are emerging candidates for parameter-efficient learning, yet most rely on
qubit hardware that needs cryogenic operation, unsuitable for edge deployment. Continuous-variable (CV) photonic
quantum computing, which operates at room temperature, offers a complementary route. We investigate a hybrid classical-CV
quantum classifier for oral cancer detection from smartphone images. The pipeline combines a MobileNetV1 feature extractor, principal component analysis to 16 dimensions, and a parameterized CV-QNN of displacement, interferometric, and Kerr gates on a photonic backend. We propose a simplified $\Phi \circ D \circ U_1$ CV-QNN architecture that cuts trainable parameters 40-45% relative to the standard CV-QNN layer of Killoran et al. (2019a), and identify dimensionality-reduction and encoding-restriction strategies that mitigate barren plateaus, raising loss-gradient variance by roughly 58 orders of magnitude. Whether the simplified layer beats the full layer is width-dependent: the full layer holds a small but significant edge at two qumodes, whereas the simplified layer is significantly better at four qumodes using 44% fewer parameters. The strongest model, a four-qumode simplified CV-QNN with only 18 parameters, attains the highest validation AUC of all models, exceeds a 55-parameter classical baseline using 67% fewer parameters, and reaches 100% calibrated test accuracy across all seeds. These results support CV photonic
quantum machine learning for parameter-efficient, room-temperature medical image classification and motivate progress toward edge
quantum AI.
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Exactly Solvable and Integrable Systems
Perturbation theory for kinks of the defocusing modified Korteweg-de Vries equation
Nicholas J. Ossi, Barbara Prinari, Theodoros P. Horikis et al. (+1 more)
In this work we develop an integrable perturbation theory for the defocusing modified Korteweg-de Vries kink solution based on the squared eigenfunction expansion associated with the underlying Zakharov-Shabat scattering problem. We derive the completeness relation for the squared eigenfunctions appropriate to the kink background, establish the adjoint structure needed to handle perturbations of both the continuous and discrete spectral components, and obtain explicit
evolution equations for the perturbed kink parameters at leading order. The study of the first order correction shows that perturbations generically produce a radiative shelf in front of the kink. We also apply our results to certain physically relevant perturbations and show that the predictions are consistent with direct numerical simulations.
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All authors Nicholas J. Ossi, Barbara Prinari, Theodoros P. Horikis, Dimitrios J. Frantzeskakis
Cosmology and Nongalactic Astrophysics
Cancellation of one-loop time dependence in superhorizon curvature perturbations from all scales
Keisuke Inomata
We show the conservation of the superhorizon
curvature perturbations at one-loop level in spatially-flat gauge, including contributions from loop wavenumbers on all scales in the decoupling limit, $\epsilon (\equiv -\dot H/H^2) \to 0$. In contrast to previous works, we do not assume a hierarchy $k \gg q$ between the wavenumber of the loop integral, $k$, and that of the power spectrum, $q$, and we explicitly include the regime $k \lesssim q$. Taking into account the nonlinear relation between the inflaton fluctuation and the
curvature perturbation with the $\delta N$ formalism, we show that the apparent time dependence of the one-loop
curvature power spectrum cancels once all contributions, including boundary terms, are combined consistently.
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High Energy Physics (Theory)
The cosmology of long range Yukawa interactions in general backgrounds
Guillem Dom`enech and Panagiotis Giannadakis
Long-range forces in the early universe may lead to early structure formation and, perhaps, to
primordial black holes. We generalise previous studies of
fermions coupled to a light scalar field by considering general scalar-field-dependent couplings in cosmological backgrounds with a constant equation of state. We identify two broad regimes: a scaling regime, in which the scalar field oscillates around a point of vanishing
fermion mass, and an asymptotic regime, in which the field evolves toward configurations where the
fermions recover their bare mass. We show that the scaling regime arises from an approximate scale invariance in the scalar-
fermion action, which becomes an approximate conformal invariance at late times. In the scaling regime, the ratio between the scalar and
fermion energy densities is approximately constant. Our work provides a first step toward a general study of the growth of perturbations in this system.
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High Energy Physics (Theory)
Spinor-helicity formalism for continuous-spin particles
Thomas Basile, Xavier Bekaert, Felipe Figueroa et al. (+1 more)
We propose a new formulation of continuous-
spin particles (CSP) with the help of a single two-component spinor to build asymptotic states. This formulation allows to write down amplitudes in a straightforward way, similar to the massless spinor-helicity approach. The helicity states naturally emerge upon decomposing into components of a fixed homogeneity degree. We show that CSP amplitudes can be understood as the infinite-
spin limit of amplitudes of massive particles and, similarly to the scattering of black holes, a certain universal factor exponentiates. In analogy with the recent discovery of collinear amplitudes in self-dual theories, we find nontrivial CSP collinear amplitudes where the collinear fractions are constrained by the dimensionful parameter characterising the various continuous-
spin particles.
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All authors Thomas Basile, Xavier Bekaert, Felipe Figueroa, Evgeny Skvortsov
High Energy Physics (Theory)
Quantum Fluctuations of the Black Hole Horizon
Ben Freivogel, Antony Speranza and Erik Verlinde
Classical black holes have sharply defined event horizons, but
quantum mechanically the horizon acquires a
quantum uncertainty, called the `
quantum width' by Marolf. We propose a definition of the
quantum width by a physical experiment involving the last moment a signal emitted from an ingoing light ray can escape to infinity. Calculations of this observable for spherically symmetric black holes in perturbative
quantum gravity reveal that the
quantum width depends on the resolution of the probe, and is often much larger than the Planck scale. For example, for Schwarzschild black holes in four dimensions in a particular regime of parameters, a piece of the horizon of size $\sigma_\perp$ has
quantum width roughly $\sqrt{l_P r_s^2/\sigma_\perp}$.
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Disordered Systems and Neural Networks · Cross-listed from cs.LG
How Width and Data Shape Generalization Scaling Laws in Quadratic Neural Networks
Julius Girardin, Emanuele Troiani, Yizhou Xu et al. (+3 more)
Understanding how performance scales jointly with model size and data is a central problem in modern machine learning. Existing theoretical works on scaling laws typically describe generalization as a function of data or compute, often in fixed-feature or infinite-width regimes and for online SGD. Here, we instead study how generalization scales with the number of trainable parameters and the number of samples in a feature-learning model. We analyze $\ell_2$-regularized empirical test error minimization in a quadratic two-layer network in a finite-sample setting with structured data. This setting allows for an explicit characterization of the generalization error as a function of the number of samples, model width, and regularization. Our results reveal a phase diagram with distinct scaling regimes as the number of parameters varies. In particular, the generalization error follows data-dependent power laws controlled by the spectral structure of the target. We further characterize the transitions between regimes, including the onset of interpolation, and their impact on generalization.
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All authors Julius Girardin, Emanuele Troiani, Yizhou Xu, Vittorio Erba, Florent Krzakala, Lenka Zdeborová
Soft Condensed Matter
Entropy functional theory for inhomogeneous fluids
Matthias Schmidt
We present an exact variational scheme for the physics of inhomogeneous classical fluids in thermal
equilibrium. A joint metadensity minimization principle is proven for the one-body density and the global interparticle distance distribution. The theory bypasses the inhomogeneous two-body density and thus remains computationally simple. A universal excess
entropy functional accounts for all many-body correlations in arbitrary pairwise interacting systems. The framework is relevant for neural functional machine learning, for soft matter design, and for predicting hyperobservables, structural correlation functions, and first-principles mechanisms of
entropy-energy competition.
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High Energy Physics (Theory)
Gravitational Compton scattering at the fourth post-Minkowskian order
Giacomo Brunello, Mario Meo and Sid Smith
We compute the classical gravitational Compton amplitude at the fourth post-Minkowskian order, $\mathcal{O}(G^4)$, within the Worldline
Quantum Field Theory framework. We derive the associated $N$-
matrix element, which provides the gravitational-wave scattering phase shift at the same order. As a nontrivial check, we show that our result agrees with black-hole perturbation theory.
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Quantum Physics
Qudit extension of parameterized IQP circuits: A generative quantum machine learning approach to integer data
Robert J. Banks, Arianna Crippa, Matthias Traube et al. (+3 more)
Parameterized Instantaneous
Quantum Polynomial (IQP)
circuits have proven useful in
quantum generative learning models, particularly for binary distributions. However, when applied to non-binary
datasets, they exhibit notable limitations: mapping integer values into
qubit-compatible binary representations often destroys the original metric structure of the data. In this paper we aim to extend them to a qudits formulation operating on an integer mapping of the data. The IQP
quantum circuit is adapted to encode each integer valued pixel into a bit-string of fixed length and
quantum gates are transformed to follow the qudit formalism. As a generative machine learning approach, a suitable loss function for the
circuit training and the calculation of the covariance
matrix among features are developed and validated on the energy deposits from single-particle electron showers in the electromagnetic calorimeter of the CLIC detector. The method proposed in this work can be also extended to other applications that utilize
quantum generative machine learning for non-binary data.
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All authors Robert J. Banks, Arianna Crippa, Matthias Traube, Josua Unger, Christian Ertler, Wolfgang Lechner
Quantum Physics
Noise-Directed Adaptive Remapping for Integer Optimization: from qubits to (encoded) qudits
Stuart Hadfield, Filip B. Maciejewski and Davide Venturelli
We extend Noise-Directed Adaptive Remapping (NDAR), a recently proposed heuristic meta-
algorithm that leverages device noise as a computational resource, to optimization problems over discrete (integer) domains. While originally introduced for unconstrained binary optimization, the proposed generalization introduces additional gauge degrees of freedom at the logical level, such that the gauge transformation applied at each iteration is no longer unique, allowing tailoring to particular encodings or
quantum hardware. We identify encoding-dependent requirements for NDAR beyond binary domains: feasibility of the noise attractor, existence of compatible gauge transformations that preserve an efficiently implementable
circuit family, and a systematic way to select the transform to apply at each step. We analyze these criteria for qudit-native and for binary, one-hot, and domain-wall
qubit encodings, using the Max-k-colorable subgraph problem as a running example. We demonstrate that these encodings can exhibit distinct advantages and tradeoffs when integrated within the NDAR framework, particularly in how noise-induced dynamics interact with the solution landscape and choice of encoding. Our results indicate that NDAR-guided noise considerations provide a new criterion for comparing device-level encoding choices for
quantum optimization. Finally, we outline directions toward experimental realization in superconducting qudit devices and further algorithmic improvements.
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Quantum Gases
Coexisting Regular and Chaotic Dynamics in the Dysprosium Feshbach Spectrum
Julie Veschambre, Alexandre Journeaux, Maxime Lecomte et al. (+7 more)
Strongly dipolar gases, such as dysprosium, erbium and thulium, exhibit dense Feshbach spectra whose level statistics have been associated with
quantum chaos arising from couplings among many molecular channels. Here, we combine a precise calibration of the Feshbach spectrum of $^{162}$Dy with spectroscopic measurements of the differential
magnetic moments of bound states associated with more than 80 resonances between 0 and 30 G. These
magnetic moments provide an eigenstate-sensitive probe of the molecular states underlying the resonance spectrum. We find that the level statistics are not uniform: resonances associated with states near the center of the
magnetic-moment distribution display enhanced level repulsion, whereas those near the lower edge remain close to Poisson statistics. Our results reveal hidden structure within the chaotic dysprosium Feshbach spectrum and identify molecular-state composition as a key ingredient in the emergence of
quantum chaos in strongly dipolar scattering.
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All authors Julie Veschambre, Alexandre Journeaux, Maxime Lecomte, Alice Belmon, Ethan Uzan, Inès de Verdelhan, Patricia Christina Marques Castilho, Jakub Zakrzewski, Jean Dalibard, Raphael Lopes