Soft Condensed Matter
Understanding quorum sensing self-organization: Clustering and defect-induced ordering of diffusing particles
Feifei Liu, Vyacheslav R. Misko, Yunyun Li et al. (+1 more)
Quorum sensing (QS) is known in biology as a form of intercellular communication mediated by signaling molecules called autoinducers. The QS protocol governs the transition from individual to collective
cell behavior once a critical population density is reached. Using numerical simulations, we investigate how defects influence the QS transition and the structural organization of the resulting colonies. Our model system consists of a mixture of slow ("cold") and fast ("hot") diffusing colloidal particles that obey the QS protocol, together with defect particles characterized by a constant diffusivity. A striking reentrant solidification of QS particles, characterized by long-range order, is induced by hot defects, whereas cold defects give rise to amorphous structures with only short-range order. These findings deepen our understanding of the QS interaction and provide a mechanism to control the degree of organization in QS systems, with potential applications in robotics, social sciences, and medicine – for instance, in overcoming antimicrobial resistance.
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All authors Feifei Liu, Vyacheslav R. Misko, Yunyun Li, Fabio Marchesoni
Quantum Physics
Environmental Memory Effects and Quantum Resource Hierarchies in Polarized Hyperon–Antihyperon Systems
Omar Bachain, Mohamed Amazioug and Rachid Ahl Laamara
Hyperon–antihyperon pairs produced in $e^{+}e^{-}\rightarrow J/\psi\rightarrow Y\bar{Y}$ ($Y=\Lambda,\Sigma^{+},\Xi^{-},\Xi^{0}$) constitute a unique high-energy platform for probing
quantum correlations through experimentally accessible
spin observables. We investigate the impact of correlated dephasing environments on the stationary and dynamical properties of logarithmic negativity,
geometric quantum discord, and $l_{1}$-norm
quantum coherence under both longitudinal and transverse beam polarizations. Our analysis reveals that environmental
memory plays a crucial role in preserving
quantum resources. In the non-Markovian regime, information backflow generates recurrent revivals of
quantum correlations and significantly delays decoherence, whereas Markovian
evolution drives the system toward asymptotic stationary states through an irreversible loss of
quantum information. The influence of beam polarization is found to be strongly channel dependent and can substantially enhance the amount of accessible
quantum correlations. A comparative investigation of different quantifiers uncovers a clear hierarchy of
quantum resources.
Quantum coherence remains robust over the widest parameter range,
geometric quantum discord survives even in regions where
entanglement is strongly reduced, while logarithmic negativity is the most sensitive to environmental degradation. This hierarchy persists for all considered hyperon channels and under both polarization configurations. The dependence of
quantum resources on the production angle, azimuthal angle, polarization degree, and
memory parameter is examined using experimental inputs from BESIII. The predicted effects are found to be compatible with the precision expected at BESIII and future high-luminosity facilities such as STCF and CEPC.
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Materials Science
Bulk Boundary Condition for Surface Calculations in Density Functional Theory
Sayan Bhowmik, Andrew J Medford and Phanish Suryanarayana
We present a bulk boundary condition formalism for surface calculations in Kohn–Sham density functional theory. The approach exploits the nearsightedness of electronic interactions in real space to restrict the calculation to a localized surface region. Within this region, the electron density is evaluated by leveraging the decay of the density
matrix, with bulk values imposed on the density and electrostatic potential in the interior, and the electrostatic potential solved subject to bulk boundary conditions. The energy and atomic forces are computed using density-
matrix-based expressions. Through representative calculations of surface and adsorption energies, we demonstrate the accuracy and efficiency of the proposed formalism.
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Quantum Physics
Measurement-Based Quantum Computing on a Photonic Chip
Jeldrik Huster, Louis L. Hohmann, Kevin Edelmann et al. (+1 more)
Integrated photonics provides a scalable platform for
quantum information processing. In this context, measurement-based
quantum computing (MBQC) offers an attractive approach in which
quantum computation is realised by adaptive measurements on highly entangled graph states, circumventing the need for deterministic
photon-
photon interactions. Here, we demonstrate MBQC on an integrated silicon photonic chip capable of generating photonic graph states with up to four
qubits. We achieve fidelities of $F_{Star} = (83.5 \pm 1.8)\,\%$ and $F_{Lin} = (75.6 \pm 1.1)\,\%$ for four-
photon star and linear graph states, respectively. We use these resource states to implement MBQC-based single- and two-
qubit gates and to demonstrate Grover's search
algorithm and the Deutsch-Jozsa
algorithm. These results establish the feasibility of reconfigurable four-
photon MBQC on an integrated photonic platform and provide a foundation for future larger-scale implementations.
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All authors Jeldrik Huster, Louis L. Hohmann, Kevin Edelmann, Stefanie Barz
Atmospheric and Oceanic Physics
Global reanalysis from observations alone with machine learning
Peter Lean, Ewan Pinnington, Patrick Laloyaux et al. (+9 more)
Earth system reanalysis
datasets are foundational for weather and
climate research and provide the gridded training data used by most machine learning weather prediction systems. Here we show results from a prototype system that suggest that machine learning models trained only on Earth system observations can potentially be used to generate multi-decade global reanalyses without using physics-based numerical models. The resulting gridded fields capture large-scale atmospheric structure and variability across multiple timescales, while exhibiting signs of physical coherence in several key dynamical diagnostics. Evaluations of the prototype against held-out independent atmospheric observations indicate that the root mean square vector error of upper-level winds is close to that of ERA5 when compared at a consistent resolution, and that the standard deviation of the error at the surface is between that of 4th- and 5th-generation ECMWF reanalyses (ERA-Interim and ERA5). Furthermore, while traditional reanalysis production is computationally expensive, typically taking several years to produce, the reanalysis presented here was generated during the course of a single working day. These results suggest that observation-trained machine learning models offer a promising new approach for reanalysis production from observations alone.
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All authors Peter Lean, Ewan Pinnington, Patrick Laloyaux, Mihai Alexe, Eulalie Boucher, Simon Lang, Tomas Kral, Paul Poli, Hans Hersbach, Niels Bormann, Matthew Chantry, Anthony McNally
Quantum Physics
Complex spacing ratio statistics in the partially open asymmetric quantum baker map
Leonardo Ermann, Pablo Sesin, Alejandro M. F. Rivas et al. (+2 more)
We study the complex
eigenvalue statistics of the asymmetric
quantum baker map with partial projective openings. The classical asymmetric baker map, with its discontinuity at $q=2/3$, is fully chaotic, has no reflection
symmetry, and provides a clean setting with tunable escape rate and fractal repeller dimension. We consider three distinct opening geometries in position space: localized (contiguous channels), random, and uniform (equispaced channels), all controlled by a tunable amplitude reflectivity parameter $\rho$ that interpolates between the fully open ($\rho=0$) and the closed ($\rho=1$) limits. We use the partially truncated circular
unitary ensemble (PTCUE) as the random
matrix theory
benchmark. The main focus is on the joint distribution of the complex spacing ratio $z$, defined as the ratio of the distances from an
eigenvalue to its nearest and next-nearest neighbors in the complex plane. We find a smooth crossover from a quasi-1D spectral regime, where
eigenvalues cluster near the unit circle and the phase distribution of $z$ is peaked, to a two-dimensional Ginibre-like regime, where the distribution becomes nearly uniform and level repulsion is fully developed. Both the number of open channels $M$ and the reflectivity $\rho$ modulate this crossover, and $\rho$ provides an additional continuous control even at fixed opening size. All three opening models converge to PTCUE statistics at large $M$, while differences are most pronounced for the localized model at small $M$. No evidence of an abrupt transition is found. This crossover which suggests a universal behavior, has deep consequences for open
quantum and wave-chaotic experiments.
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All authors Leonardo Ermann, Pablo Sesin, Alejandro M. F. Rivas, Pablo D. Bergamasco, Gabriel G. Carlo
Soft Condensed Matter
Directed assembly of tetrahedral patchy particles
Xin Yin, Ekaterina Kostyurina, Bert Nickel et al. (+2 more)
Colloidal particles with prescribed valency such as the tetrahedral patchy particles have long been seen as a viable route to technologically relevant open
lattice structures on the scale of hundreds of nanometers. However, conceptual limitations and resulting competing local bonding configurations often lead to mixed
lattice phases. Here, we present a DNA-origami enabled approach to controlling the attachment of tetrapod building blocks in predictable ways. By varying the relative strength of two designed binding configurations we are able to direct the assembly of tetrapod particles into diamond cubic, twinned diamonds, stacking-disordered mixtures, hexagonal diamonds, and sII clathrates. Under specific conditions, the diamond structures are interpenetrated by additional networks, resulting in triple cubic and triple hexagonal diamond structures. The 440 nm large unit
cell of the clathrates shifts structural reflections into the visible range, giving these rationally designed, self-assembled
crystals structural color.
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All authors Xin Yin, Ekaterina Kostyurina, Bert Nickel, Tim Liedl, Gregor Posnjak
Cosmology and Nongalactic Astrophysics
Alcock-Paczynski Blinding Scheme for the Ly-$\alpha$ Forest Analysis
G. Perez-Sanchez, S. F. Beltran, G. Niz et al. (+45 more)
We present and validate a blinding method for the Lyman-$\alpha$ (Ly$\alpha$) forest analysis based on a modification of the Alcock-Paczynski test. In order to hide the background expansion history, the method employs a geometrical shift of each
quasar (QSO) forest in wavelength space, once the
quasar continuum has been fitted and the fluctuation field is extracted. The
redshift positions for the QSO sample are also changed in a consistent manner. We show that the method remains effective when applied to real data, where contamination from metals and Lyman-$\beta$ is intrinsically mixed with the Lyman-$\alpha$ forest. This limitation is primarily visible in the 1D correlation function, where other blinding strategies can mitigate the effect. To assess its effectiveness, the prescription is tested against a series of
datasets of increasing complexity: from idealized low-noise mocks, to realistic DESI year one synthetic
datasets, and finally to data from DESI first data release (DR1), using both the auto (Ly$\alpha\times$Ly$\alpha$) and cross (Ly$\alpha\times$ QSO) correlations. We find that the method robustly shifts the BAO peak position from the 3D correlation functions to the expected value for cosmology changes of around 5% in the matter content, without altering the shape of the posteriors in the model parameters. In conclusion, this catalog-level blinding strategy is a viable method for cosmological inference with the Lyman-$\alpha$ forest, particularly if a cross-analysis with other tracers using the same blinding strategy is pursued.
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All authors G. Perez-Sanchez, S. F. Beltran, G. Niz, S. Brieden, L. Verde, A. Font-Ribera, J. Aguilar, S. Ahlen, D. Bianchi, D. Brooks, T. Claybaugh, A. Cuceu, A. de la Macorra, B. Dey, P. Doel, S. Ferraro, J. E. Forero-Romero, E. Gaztañaga, S. Gontcho A Gontcho, A. X. Gonzalez-Morales, G. Gutierrez, H. K. Herrera-Alcantar, K. Honscheid, D. Huterer, M. Ishak, R. Joyce, A. Kremin, O. Lahav, A. Lambert, M. Landriau, L. Le Guillou, M. Manera, P. Martini, R. Miquel, S. Nadathur, N. Palanque-Delabrouille, W. J. Percival, F. Prada, I. Pérez-Ràfols, G. Rossi, E. Sanchez, E. F. Schlafly, D. Schlegel, M. Schubnell, J. Silber, D. Sprayberry, G. Tarlé, B. A. Weaver
Quantum Physics
Unveiling Semiclassical Structures in Quantum Chaotic Eigenstates Using Neural Networks
J. Montes, F. Borondo and Gabriel G. Carlo
Physics-informed neural networks and neural
quantum states have consolidated a new paradigm to analyze and discover physical phenomena through constrained neural parametrizations. In this context, we investigate whether the semiclassical structure of the eigenfunctions of a
quantum chaotic system can be unveiled through unsupervised learning. To this end, we train a "
quantum dictionary", formulated as an overcomplete autoencoder, that sparsely represents the eigenstates of the system, using as an illustration the
quantum baker map. The only explicit physical information imposed on the dictionary atoms is their localization in phase space, without providing any kind of information about the periodic orbits of the corresponding classical system. The model achieves high fidelity in reconstructing eigenstates not used during training. By comparing the learned atoms with an independently constructed "semiclassical dictionary", we find that they spontaneously localize on the periodic orbits and develop scar-like structures. This result is interesting in two ways: a localization constraint is sufficient to recover nontrivial semiclassical organization from spectral data and at the same time periodic orbits confirm their fundamental role in the structure of
quantum chaotic eigenfunctions. More generally, our proposed architecture opens a new route to learning representations whose atoms optimize other chosen physical properties.
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High Energy Physics (Theory)
The Energy-Momentum-News Complex near Future Null Infinity
Jelle Hartong, Emil Have, Vijay Nenmeli et al. (+1 more)
We study asymptotically flat
vacuum solutions of general relativity in three and four dimensions, with an emphasis on the
geometric structures that emerge near null infinity. We construct asymptotic solutions to the three- and four-dimensional Einstein equations near future null infinity, which is a conformal Carroll
manifold, starting from the most general Carroll metric data allowed by the Einstein equations. We use a Carroll-covariant version of Bondi–Sachs gauge, whose residual transformations act on the boundary Carroll geometry and shear as boundary diffeomorphisms, Weyl transformations and Carroll boosts. We then define a boundary energy-momentum-news complex at future null infinity by varying a suitably renormalised action with respect to the boundary Carroll metric data and shear. This involves adding boundary terms to the Einstein–
Hilbert action on a cut-off surface near future null infinity. The boundary energy-momentum-news complex obeys two relations due to the boundary diffeomorphism and Weyl gauge invariance of the renormalised action. A third relation, due to the Carroll boost, is anomalous, and the corresponding anomaly is obtained from the variation of the renormalised action. Together, these Ward-type identities obeyed by the boundary energy-momentum-news complex lead to a Carroll-covariant generalisation of the Bondi loss equations.
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All authors Jelle Hartong, Emil Have, Vijay Nenmeli, Gerben Oling
Materials Science
Quantum Dot Moiré from Crossed MoS2 Nanoribbons
Xinting Shuai, Hao Zhang, Wenjing Wu et al. (+22 more)
Twisted atomically thin layers have attracted much
attention for Moiré potential and correlated
quantum phenomena. However, existing Moiré superlattices have largely been limited to extensive wavefunction without lateral confinement. Here we introduce a new platform where 1D nanoribbons of 2D MoS2 grown by vapor deposition can be easily superposed at various angles from stacking and transferring, to form Moiré
quantum dots at their intersections with unique
exciton physics. Angle-dependent Moiré intersections show enhanced
exciton emission at commensurate angle 22 deg, which demonstrates faster relaxation at the cryogenic temperature. A size-dependent study further exhibits a reduced
exciton energy and soften out-of-plane interlayer coupling for smaller Moiré areas. Our results reveal
exciton physics turnability via precise overlapping of 1D nanoribbons.
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All authors Xinting Shuai, Hao Zhang, Wenjing Wu, Chongning Wu, Maryam Amiri, T. A. M. Ragib Shahriar, Dian Pan, Zhi Kai Ng, Tymofii Pieshkov, Leeza Dutta, Yijun Zhou, Rohith Narra, Luke Van Leeuwen, Jishnu Murukeshan, Luyao Shi, Jiawei Lai, Atin Pramanik, Bipin Kumar Gupta, Edwin Hang Tong Teo, Robert Vajtai, Xiang Zhang, Hanyu Zhu, Shengxi Huang, Aditya D. Mohite, Pulickel M. Ajayan
Strongly Correlated Electrons
Perturbations in the spin-orbital liquid (the Yao-Lee model)
A. M. Tsvelik
I investigate the stability of the
spin-orbital
liquid described by the Yao-Lee model in the presence of multiple perturbations that naturally arise in a recently proposed microscopic realization. While most perturbations are irrelevant and do not qualitatively alter the exact solvability, we find that the Kitaev interaction plays a special role: it couples to the $ \mathbb{Z}_2 $ gauge field and renders the visons mobile.
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Disordered Systems and Neural Networks
Lecture notes on random matrix theory: the results, the applications, and the analytical tools
Joseph W. Baron
Random
matrix theory has established itself as a theoretical cornerstone of the mathematical sciences over the past century. It has undeniable utility in areas of research as diverse as
nuclear physics, finance, ecology and disordered systems. The purpose of these notes is twofold. First, the most famous and widely used classic results are derived in a pedagogical manner, mostly using the comparatively elementary and transparent cavity method. The significance of each result is then demonstrated in the context of a particular application. There are also some select exercises at the end of each section. In the second part of these notes, a reference guide of analytical techniques for the random-
matrix/disordered-systems practitioner is provided. Introducing the diagrammatic, replica, path-integral, and supersymmetric formalisms from first principles, we rederive some of the aforementioned classic results, particularly focussing on the simplest one – the semicircle law. Innovations such as the population dynamics method and the tools of free probability theory are also included. We discuss the merits of each analytical approach, and we highlight the contexts in which each becomes particularly useful.
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Mathematical Physics
An edge-bicolored graph approach to the Ising model on random regular graphs
Michael Borinsky, Shiyue Ren and Maximilian Wiesmann
We give an exact solution of the
ferromagnetic Ising model on a random regular graph ensemble via analytic combinatorics. Expressing the partition function as the generating function of labeled edge-bicolored graphs, we obtain the free energy in the thermodynamic limit from the asymptotic enumeration of these graphs. A simple analysis of the resulting formula reveals a second-order phase transition with critical exponents of the mean-field universality class.
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High Energy Physics (Phenomenology)
Lepton mixing from the $\Delta(96)$ Modular Littlest Seesaw
Hai-Zhi Hao, Li-Na Yan, Xiang-Gan Liu et al. (+1 more)
We perform the first comprehensive and model independent study of Modular Littlest Seesaw models based on the finite modular group $\Delta(96)$. We construct the vector-valued modular forms (VVMFs) for all irreducible representations of modular $\Delta(96)$, classify the inequivalent
symmetry-preserving fixed points, and derive the corresponding
alignments of the low-weight and next-to-lowest-weight triplet VVMFs. These results allow an exhaustive scan over the residual
symmetries in the charged
lepton, atmospheric
neutrino, and
solar neutrino sectors. We identify 35 phenomenologically viable and inequivalent breaking patterns, including 21 with normal ordering and 14 with inverted ordering. The resulting Dirac
neutrino mass
matrices go beyond the conventional CSD$(n)$ structure, yielding new fixed PMNS columns and novel correlations among the
lepton mixing parameters beyond the TM$_1$ paradigm. The viable models are highly predictive, giving narrow ranges for
neutrino masses, mixing parameters and CP phases, and can be stringently tested by upcoming experiments such as JUNO, DUNE and T2HK.
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All authors Hai-Zhi Hao, Li-Na Yan, Xiang-Gan Liu, Cai-Chang Li
Plasma Physics
Analysis of collisional and facility effects in a magnetic nozzle plasma expansion
Manuel Cortés-Hernán, Mario Merino, Diego García-Lahuerta et al. (+1 more)
An axisymmetric, quasineutral three-fluid model is proposed to study the
plasma expansion in a
magnetic nozzle under the presence of neutrals coming either from the
plasma source or as an homogeneous background. As a difference with other models, electron cooling in the plume is achieved by treating the electron energy flux as mainly convective and without the need to postulate any anomalous resistivity. Solutions are presented for the electron high-magnetization limit, in which the electron main magnitudes can be integrated along
magnetic lines. Ionization, elastic and charge-exchange collisions with neutrals do not change the main qualitative features of the
plasma expansion, known from previous collisionless models. Ionization enhances the
plasma flow in the nozzle, and leads to additional electron cooling, which decreases the electric potential fall along the nozzle. The efficiency of the nozzle is quantified in terms of the gain of
magnetic thrust and the plume divergence angle. Two types of boundary conditions are discussed for the electron flow: local current ambipolarity conditions at the nozzle throat and global current-free conditions at the outer boundary (i.e., metallic
vacuum chamber walls). These last ones are shown to be physically more reliable: they introduce the influence of the chamber walls on the
plasma expansion by shaping the ambipolar electric field; they permit the extrapolation to undisturbed free space conditions; and they approximate better experimental trends with the background pressure.
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All authors Manuel Cortés-Hernán, Mario Merino, Diego García-Lahuerta, Eduardo Ahedo
Quantum Physics
Multi-agent Autoformalization of Tensor Network Theory
Sirui Lu, Erickson Tjoa and J. Ignacio Cirac
We build a team of specialized large
language-model
agents and present an
agent-driven workflow for research-level formalization in theoretical physics, with the autoformalization of the fundamental
theorem of
matrix-product states as a demonstration. The
agents, coordinated through a structured mathematical blueprint and periodic human review, orchestrated and executed the full formalization autonomously. For some statements, the
agents were able to explore new proof routes that are not part of the standard literature. Along the way the
agents produced extensive tensor-network and
quantum-information libraries not previously available in Mathlib, Lean's mathematical library. As a physical application, the formalization also extends towards
symmetry-protected topological phases in one dimension. We find that the main bottleneck in large-scale autoformalization is enforcing mathematical intent and we provide a detailed study of the full process and various subtleties involved. We release the codebase as the library \href{https://github.com/LionSR/TNLean}{TNLean}, together with a \nChapters{}-chapter \href{https://lionsr.github.io/TNLean/blueprint/}{blueprint} of the formalization effort.
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High Energy Physics (Phenomenology)
Neutrino Masses and Dark Matter Stability in 3HDMs with Minimal Non-Abelian Discrete Symmetries
Cesar Bonilla and Andres Layana-Ramirez
We present minimal three-
Higgs-doublet models (3HDMs) based on global non-Abelian discrete
symmetries that simultaneously explain
neutrino masses and dark matter stability. A residual $Z_2$ parity from the spontaneous breaking of the new
symmetry stabilizes the dark matter candidate, which runs in the loop generating
neutrino masses at one loop alongside a tree-level type-I seesaw contribution. We identify $S_3$ and $D_4$ as the smallest non-Abelian groups realizing this framework and determine the minimal models in both cases that are consistent with current
neutrino oscillation data. The resulting models conserve CP in both the Yukawa and scalar sectors.
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Mathematical Physics
Kime-Representation Formulations of Three Open Problems in the Foundations of Classical Mechanics: Uncertainty, Invariant Entropy, and Directional Degrees of Freedom
Ivo D. Dinov
We give mathematically self-contained formulations, in the complex-time (kime) representation, of three open problems from the foundations of classical mechanics: (I) the extension of the classical entropic uncertainty principle to non-canonical variables and to multiple degrees of freedom; (II) the characterization of coordinate-invariant measures and
entropies, i.e., the question of why continuous physical quantities must be paired for an invariant
entropy to exist; and (III) the construction of a classical relativistic directional degree of freedom (a classical analogue of a
spin-1/2 system). Throughout, the kime phase is interpreted {statistically as a latent circular random variable whose law \Phi models the intrinsic trial-to-trial variability of repeated, identically controlled experiments indexed by the kime magnitude. The mathematical bridge is an exact
symplectic identification of the kime cone with the action-angle chart of a one-degree-of-freedom phase space, under which the kime measure is the Liouville measure and the phase law becomes the angular conditional of a Liouville density. Specifically, we (i) prove a sharp entropic uncertainty relation on the kime cylinder whose extremal family is von Mises x Gaussian, together with a sharp circular Fisher-information inequality saturated exactly by von Mises laws; (ii) prove an exact non-canonical uncertainty relation in which the correction term is the
geometric mean of the Poisson bracket, clarifying the conjectured role of the expected bracket; (iii) prove aggregate multi-degree-of-freedom bounds via the Williamson normal form and Fischer's inequality, and isolate the per-degree-of-freedom refinement as a precise open problem of
symplectic Schur-Horn type; (iv) prove that
diffusion of the kime phase produces monotone
entropy growth with the equipartitioned (Haar-uniform) phase law.
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Quantum Physics
Quantum Sensors for Chemistry and Materials Science
Piotr Put, Arjun Pillai, Xuan Hoang Le et al. (+2 more)
The advancement of chemistry and materials science relies on transformative analytical tools which can overcome the sensitivity, spatial resolution, and throughput limitations of conventional techniques. This review explores the application of
quantum sensors - specifically optically pumped magnetometers (OPMs) and nitrogen-vacancy (NV) centers in diamond - as robust platforms for molecular and materials analysis. We contrast the extreme
magnetic sensitivity of macroscopic OPM ensembles with the atomic-scale resolution and
multimodal capabilities of solid-state NV centers. We highlight their deployment in zero- to ultralow-field and nanoscale NMR spectroscopy, real-time reaction monitoring, and transient radical and pH detection. Furthermore, we discuss their integration into high-throughput chemical assays and non-destructive materials diagnostics, such as operando battery monitoring. With the ongoing commercialization of these technologies and advances in
quantum-enhanced sensitivities,
quantum sensors are poised to routinely address complex real-world analytical challenges.
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All authors Piotr Put, Arjun Pillai, Xuan Hoang Le, Mikhail D. Lukin, Hongkun Park
Disordered Systems and Neural Networks · Cross-listed from cs.LG
Explaining Near-Zero Hessian Eigenvalues Through Approximate Symmetries in Neural Networks
Marcel Kühn and Bernd Rosenow
The Hessian of the training loss governs the local geometry of the loss landscape, yet despite existing explanations for its largest
eigenvalues, the origin of the vast multitude of vanishingly small
eigenvalues remains elusive. We argue that the bulk consists of the weakly lifted pseudo-Goldstone modes of the continuous
symmetries of the network parametrization. In deep linear networks these
symmetries are exact: they generate flat directions and hence exact zero modes, whose eigenvectors we construct explicitly. Introducing a ReLU nonlinearity as a perturbation, we show that it breaks these
symmetries weakly and explicitly. Resolving the spectrum at the level of eigenvectors, we find that the high-
curvature directions are orthogonal to the
symmetry subspace, while the bulk lies almost entirely within it. We demonstrate the mechanism in a two-layer ReLU student–teacher model and in a network trained on CIFAR-10. A convolutional example demonstrates that the same diagnostic extends beyond fully connected layers. Together, these results link the Hessian bulk to weakly broken
symmetries and clarify the origin of near-zero modes.
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Statistical Mechanics
Fluctuation theorems for autonomous work
Christopher Jarzynski, Sebastian Deffner and Saar Rahav
Classical fluctuation
theorems for work have been obtained theoretically, and verified experimentally, within a non-autonomous framework in which work is performed on a system of interest, ${\cal S}$, by the external manipulation of a work parameter, such as a piston's position. Here we obtain fluctuation
theorems within an autonomous framework in which ${\cal S}$ exchanges energy with a reversible work source, ${\cal R}$. The two subsystems, ${\cal R}$ and ${\cal S}$, interact with one another as they evolve under
Hamiltonian or
stochastic dynamics, without external intervention. In this setting, we must account for the back-action of ${\cal S}$ on ${\cal R}$, which is absent in the non-autonomous setting. We obtain autonomous versions of standard fluctuation
theorems for work and
entropy production. In each case, we argue, the autonomous fluctuation
theorem reduces to its non-autonomous counterpart when ${\cal R}$'s inertia becomes infinitely large.
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General Relativity and Quantum Cosmology
Finite mass two throat wormholes: global light rings, branch resolved strong lensing, and scalar transmission
Anirudh Pradhan, K. Ghaderi, M. Zeyauddin et al. (+1 more)
We introduce a static, horizonless, asymptotically flat two throat wormhole family in which one global metric determines the geometry, effective source, null dynamics,
lensing, and test field propagation. A finite mass deformation of a quartic
embedding profile produces two symmetric throats and an intermediate equator, while the associated Misner–Sharp mass tends to the same finite value at both asymptotic ends. The temporal sector yields the same mass parameter, and the Einstein tensor defines a single conserved anisotropic source. In addition to the local
flare out identity, the complete radial averaged null functional is obtained exactly and is strictly negative. The global null potential admits a complete phase classification for all positive masses and nonnegative
redshift deformation. Depending on the parameters, the global unstable set consists of throat rings, four off throat rings, or exterior rings accompanied by a subcritical equatorial ring. In the four ring phase, all unstable rings have the same impact scale but the inner and outer branches have different Lyapunov exponents. We derive the logarithmic strong deflection coefficients analytically and show that the cross throat coefficient is the sum of the contributions from every global maximum traversed by the ray. Direct numerical integration verifies these coefficients. The scalar scattering problem exhibits phase dependent barriers and resonant transmission. The resulting model provides a finite mass setting in which
topology, averaged energy conditions, branch resolved strong
lensing, and wave transmission are derived from one spacetime.
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All authors Anirudh Pradhan, K. Ghaderi, M. Zeyauddin, K. Karimizadeh
Quantum Physics
Super-Logarithmic Entanglement Scaling in a Monitored Superconducting Chain
Rui-Jing Guo and Zhi-Yuan Wei
We study the
entanglement dynamics of a one-dimensional spinful $s$-wave
superconductor subjected to local continuous measurements. In the rare-measurement regime, we derive a replicated Keldysh non-linear sigma model (NLSM) to describe the steady-state
entanglement. Within this field-theoretic framework, the interplay between measurement dephasing and superconducting pairing constrains the low-energy, long-wavelength fluctuations to an $\mathrm{SO(R)}$ target
manifold. A one-loop renormalization-group analysis shows that the theory develops a weak-anti-localization flow, stabilizing a critical phase with super-logarithmic scaling of the steady-state
entanglement. Our field-theoretic results explain the numerical evidence reported in the companion Letter [arXiv:2604.04375] and demonstrate that such a critical phase can emerge in a one-dimensional topologically trivial
superconductor without relying on topological protection.
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Quantum Physics
Improved GKP magic states from error-corrected non-Gaussian quantum states
Sharon David, Jack Davis, Ulysse Chabaud et al. (+1 more)
Gate teleportation, together with magic state
distillation, is a promising route towards fault-tolerant, universal computation. In the context of bosonic
quantum computation, Baragiola et al. PRL 123(20).200502 (2019) showed that within the framework of Gottesman–Kitaev–Preskill codes, encoded magic states suitable for
distillation can be produced by error correcting Gaussian states, such as the
vacuum. Here, we show that applying the same framework to simple non-Gaussian input states can significantly improve the quality of the magic states obtained, reducing the overall resources for the complete
distillation procedure. We focus on superpositions of coherent states or Fock states, showing that many can lead to improvements in the generation of high-quality encoded magic states, which in some cases reduces the resources required for magic state
distillation by about a factor $3$. We also investigate the primary source of these improvements and find that, unlike what was previously conjectured, the suitability of input states is not fully explained by
symmetry arguments. Instead, the best states seem to avoid projection near stabilizer states as a result of the error correction procedure.
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All authors Sharon David, Jack Davis, Ulysse Chabaud, Francesco Arzani
Astrophysics of Galaxies
On the detection of Population III galaxies: Emission Line Diagnostics for Hybrid Stellar Populations
S. Goswami, J. M. Vílchez, C. Kehrig et al. (+2 more)
Identifying Population III (Pop III)
stars, the first generation of metal-free
stars in the early Universe, remains a central challenge in astrophysics. High-ionization emission lines, such as HeII are commonly used as tracers of Pop III signatures. However, realistic
galaxies may host hybrid
stellar populations, including both Pop III and metal-enriched Population II (Pop II)
stars, complicating the interpretation of observed spectra. We aim to investigate how hybrid Pop III/Pop II
stellar populations affect emission line diagnostics and assess the detectability of Pop III
stars across different
galactic environments and
redshifts. We select
galaxies with varying Pop III-to-total mass ratios from the IllustrisTNG cosmological simulations. Using self-consistent photoionisation models, we compute integrated spectra by adopting local physical conditions from the simulations to study the resulting emission line diagnostics. We find that emission line diagnostics are strongly dependent on the relative Pop III contribution. Current diagnostics can identify
galaxies dominated totally by Pop III
stars but fail for systems where Pop II
stars contribute significantly, introducing degeneracies in interpreting observed spectra. Our results highlight the limitations of existing emission line diagnostics in hybrid systems and emphasize the need for additional methods that account for mixed
stellar populations to reliably detect Pop III
stars during and after the epoch of reionization.
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All authors S. Goswami, J. M. Vílchez, C. Kehrig, A. Ferrara, J. Iglesias-Páramo
General Relativity and Quantum Cosmology
Charging up regular black holes
Raúl Carballo-Rubio, Chiara Coviello and Vania Vellucci
We present a general construction of charged regular black holes as solutions of a generalization of the Einstein–Maxwell field equations in spherical
symmetry in which the Einstein tensor is deformed into an identically conserved tensor containing up to second derivatives of the gravitational field. The generality of the construction allows us to define the field equations satisfied by generic regular black holes when becoming charged. The conditions that guarantee regularity of charged solutions are evaluated and shown to be more stringent than the regularity conditions for uncharged solutions. This implies, in particular, that the charged versions of the Bardeen and Hayward black holes become singular. Improved versions of the Bardeen and Hayward metrics that remain regular when charged are proposed. Our results indicate that regularizing the
vacuum solutions of general relativity is, in general, not enough to yield regular solutions in other situations of physical interest. The implications that follow for the construction of realistic regular black holes, in which aspects such as rotation and the presence of matter fields are taken into account, are discussed.
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Statistical Mechanics · Cross-listed from math.NA
Thermodynamic Structure and Composition in Nonlinear Convection-Diffusion
J. J. Segura
Nonlinear convection–
diffusion systems play a central role in transport phenomena, including mass transfer, heat transfer, porous-media transport, and coupled continuum processes with source, exchange, and interface effects. In such systems, the key question is often not only which governing partial differential equation is used, but whether the model preserves a consistent thermodynamic balance under the operations that arise naturally in transport analysis: restriction to subdomains, coupling across interfaces, linearization near
equilibrium, and discretization for computation. This paper develops a continuum-first framework for open nonlinear convection–
diffusion systems in which thermodynamic consistency is formulated as a free-energy balance with nonnegative bulk dissipation and explicit boundary and source contributions. Within this setting, nonlinear transport systems are defined as structured objects built from admissible state fields, storage functionals, constitutive flux decompositions, sources, and boundary ports. We prove that the thermodynamic balance is preserved under exact structure-preserving transformations, restriction to subdomains, local-to-global reconstruction over compatible domain decompositions, and power-conserving interconnection of open subsystems. We then derive classical linear convection–
diffusion models as tangent thermodynamic descendants at
equilibrium and show that the same invariant survives weak formulation, semidiscretization, and fully discrete time stepping when the numerical design respects thermodynamic structure. Nonlinear drift–
diffusion and porous-medium convection–
diffusion are used as explicit examples. The resulting contribution is a compositional transport framework in which the second law remains visible across continuum modeling, subsystem coupling, linear approximation, and computation.
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Quantum Physics
Routing Techniques for Error-Corrected Silicon Spin Qubit Quantum Architectures
Julian Shen, Ludwig Schmid and Robert Wille
Silicon
spin qubits have emerged as a promising
qubit technology due to their favorable scaling and fabrication properties. However, efficiently compiling
quantum circuits onto
spin qubit platforms remains challenging, particularly when accounting for hardware constraints and the high sensitivity to static defects. Existing compilation approaches for
spin qubits either largely ignore error correction, despite its critical role for large-scale
quantum computation, or focus on low-level schedule constructions, missing a high-level compilation and routing for logical, error-corrected
algorithms. To address this gap, we introduce a compilation framework for
spin qubits based on the recent snakes on a plane model, which utilizes a 2D surface code and
qubit teleportation to mitigate errors. Building on this model, we propose shortest-path and rotation-based
algorithms as two novel classes of
qubit-routing techniques, along with additional defect-handling and initial-mapping strategies. We evaluate both
algorithms across diverse architectural settings and problem sizes, demonstrating that shortest-path methods excel in sparse, low-defect scenarios, while rotation-based approaches perform better in high-density environments. An open-source implementation of our framework is publicly available on GitHub as part of the Munich
Quantum Toolkit (MQT) at https://github.com/munich-
quantum-toolkit/
spin-
qubit-routing.
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Cosmology and Nongalactic Astrophysics
Multipolar structure of the local expansion rate from incomplete sky data
João G. Vicente, Thiago S. Pereira, Ricardo G. Rodrigues et al. (+2 more)
Using the Cosmicflows-4 data, we reconstruct the first multipolar moments of a general function describing the local expansion rate. In addition to the conventional harmonic approach, we employ a basis of symmetric and trace-free tensors to characterize the anisotropies of the expansion rate, allowing us to identify all directions associated with each of its multipoles. Focusing on objects in $z\in[0.01,0.05]$ in the CMB rest frame, we derive all $2\ell+1$ degrees of freedom in the multipoles $\ell=1,2$ and 3, which are split into one amplitude and $\ell$ unit vectors per multipole. To mitigate anisotropies induced by incomplete sky coverage, we introduce a pixel-based mask that removes poorly sampled pixels. The full-sky expansion rate is reconstructed using two independent approaches: a pseudo-inverse of the multipole-coupling kernel induced by the mask, and a maximum-likelihood estimate of the underlying full-sky field. These approaches are validated through simulations that explore different mask resolutions,
cosmic variance and statistical noise. We find that the quadrupole and octupole amplitudes are consistent (at $95\%$ C.L.) with the expectations of a $\Lambda$CDM universe with linear and mild nonlinear perturbations, where the anisotropies of the expansion rate result from small peculiar velocities. The dipole amplitude, however, is inconsistent with $\Lambda$CDM predictions at 3.3$\sigma$, with a direction $(l, b) = (290^\circ, -4^\circ) \pm 5^\circ$ consistent with a bulk flow. This signal comes predominantly from sources in $z\in[0.03,0.05]$. Finally, we conduct
alignment tests between the dipole, quadrupole, and octupole vectors. We confirm recent findings showing that the maxima of these multipoles are approximately located at $(290^\circ,-4^\circ)$. However, detailed tests using the complete vector structure of these multipoles reveal no evidence of
alignments.
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All authors João G. Vicente, Thiago S. Pereira, Ricardo G. Rodrigues, Sandro D.P. Vitenti, Vitoria M. Gomes