Solar and Stellar Astrophysics
Two stages of magnetic filament formation in the solar convective zone
Evgeny Kuznetsov, Evgeny Mikhailov and Vlada Khvoshchinskaia
This paper presents a brief overview of studies of
magnetic filament formation in the
solar convection zone. Two stages of
magnetic filament formation and development are distinguished. The first stage can be described within the kinematic approximation for the MHD equation, since the average kinetic energy of convective motion exceeds the average
magnetic field energy. Moreover,
magnetic Reynolds number is on the order of $10^6$. Therefore, at the initial stage of
magnetic filament formation, the
magnetic field can be considered frozen-in. It turns out that at this stage,
magnetic filaments begin to form at the boundaries of convective
cells in
hyperbolic regions of the flow. These regions act as attractors for the
magnetic field. At the free boundary of the convective zone near the interfaces between convective
cells, the
magnetic field has a predominantly normal component relative to the boundary. As the
magnetic field increases, the field's frozen-in nature in the filament is disrupted, and saturation occurs due to finite conductivity. It is important to note that the
magnetic field growth and saturation in the filament at this stage can be determined by analyzing the behavior of the
magnetic field at the free boundary, which, according to observations, can be considered flat. Moreover, the formation of
magnetic filaments is independent of the internal structure of the convective
cells and is determined by the behavior of the convective flow along the free surface. In the next stage, when the
magnetic field in the filament is sufficiently strong, the
magnetic field pressure gradient begins to impede the convective flow, leading to a shift of the
hyperbolic regions toward the convective flow along the free surface. As a result, the transverse size of the filament increases and stops when the kinetic energy density and the
magnetic field energy density become comparable.
Read the full abstract ▾
Physics and Society
Mechanism underlying the scaling law of home-return probability in human mobility
Haoying Niu and Xiao-Yong Yan
Individual daily mobility exhibits a striking scaling law: the probability of returning home after a tour of $l$ locations decays as $P_{\rm ret}(l)\sim l^{-\gamma}$. While the tour-terminate-continue (TTC) model reproduces this behavior, it relies on this power law as an empirical input, leaving the microscopic origin of $\gamma$ unresolved. Here we show that this scaling emerges from a utility trade-off governed by cognitive constraints. By invoking the principle of least effort, we demonstrate that individual activity priorities follow Zipf's law, $p(r)\sim r^{-\nu}$, which directly dictates the sublinear accumulation of tour utility, $U_L(l)\sim l^{1-\nu}$. Luce's choice rule then yields $P_{\rm ret}(l)\sim l^{-(1-\nu)}$, giving the exact exponent $\gamma = 1 - \nu$.
Agent-based simulations confirm this analytical relation. Our framework bridges the gap between individual cognitive constraints and the scaling law of tour behavior, providing a microscopic theoretical underpinning for human mobility.
Read the full abstract ▾
High Energy Physics (Phenomenology)
Neutrino Dipole Moments and Radiative Signatures from Partial Compositeness
Benoît Assi and Pedro A.N. Machado
We investigate composite
neutrino models where heavy
neutrinos emerge as bound states from a near-conformal strongly coupled sector. Standard Model
neutrinos mix with these composite singlets via an inverse seesaw mechanism, where the anomalous scaling dimensions of the composite-sector operators naturally suppress light
neutrino masses to sub-eV scales. Matching the conformal dynamics onto low-energy theory yields enhanced electromagnetic transition dipole operators with couplings $d_{\mu N} \sim 10^{-6}$-$10^{-8}\,\mathrm{GeV}^{-1}$, parametrically larger than the loop-level predictions of minimal Dirac or Majorana models. We carry out a dedicated event-level simulation of the production-and-decay chain $\nu X \to \mathcal{U} X \to \nu\gamma X$ and compute the resulting event rates at MiniBooNE and MINERvA within the model, accounting for the composite production cross section and decay kinematics in detail. We further present predictions for the
photon energy, angular, and multiplicity distributions. For the
benchmark scenarios accessible at these experiments the radiative signal is predominantly single-
photon; the composite structure additionally permits fragmentation of the up-scattered state into multiple heavy
neutrinos, each decaying as $N\to\nu\gamma$, with multi-
photon final states emerging for lighter compositeness scales or higher beam energies as a qualitatively new probe of the composite dynamics.
Read the full abstract ▾
Physics Education
Classical diamagnetism at large magnetic fields
Ya. B. Bazaliy and Ammar Kasem
Many textbooks discuss the diamagnetic response of a “classical atom” to a small, adiabatically slowly applied
magnetic field. Here we solve this problem for an arbitrarily large field. This gives a more satisfying justification for the assumptions made in the small field regime, explains the role of adiabaticity, identifies the
symmetries persisting at large fields, and illustrates the range of applicability of the Larmor's
theorem.
Read the full abstract ▾
High Energy Physics (Phenomenology)
Gluon GTMD at strong coupling: fixed-spin saddle factorization and Reggeization
Kiminad A. Mamo and Ismail Zahed
Generalized transverse-momentum-dependent parton distributions (GTMDs) are the most complete two-parton correlation functions in QCD, encoding the joint spatial and momentum structure of
hadrons. Through appropriate projections and limits they yield generalized parton distributions (GPDs), transverse-momentum-dependent distributions (TMDs), parton distribution functions (PDFs), and phase-space (Wigner) distributions. We construct conformal moments of unpolarized
gluon GTMDs at strong coupling using gauge/string duality. For fixed even conformal
spin $j$, we distinguish the local boundary limit at $b_T=0$ from the finite-separation regime $b_T>0$, where the planar semiclassical amplitude is governed by a minimal worldsheet. There the GTMD moment factorizes into a universal staple-worldsheet soft factor and a stripped
spin-$j$ Witten amplitude carrying target dependence. The cusp of the renormalized minimal area generates the rapidity-logarithmic Collins-Soper structure. We derive universal ultraviolet and infrared endpoint reductions. As $b_T\to0^+$, the finite-separation sector matches onto the local conformal moment through a universal overlap kernel. At large $b_T$, after cusp/perimeter subtraction, it factorizes into target projections and infrared transfer kernels. The ultraviolet endpoint is universal within the leading saddle, whereas the infrared tail depends on the
holographic completion: soft-wall, gap-matched hard-wall, and repulsive-wall backgrounds generate algebraic, exponential, and Gaussian falloffs, respectively. Analytic continuation in $j$ yields the low-$x$ Regge regime governed by the
holographic Pomeron spectral curve. The framework describes
hadron tomography, transverse structure, rapidity
evolution, and Reggeization for GTMD moments and provides a unified starting point for
holographic studies of observables relevant to the Electron-Ion
Collider.
Read the full abstract ▾
Astrophysics of Galaxies
Globular Clusters in the Time of the JWST. I. Survey Design and First Results on Multiple Populations and Beyond
A. P. Milone, A. F. Marino, G. Cordoni et al. (+25 more)
Globular clusters (GCs) host multiple
stellar populations with distinct chemical compositions, but their properties among very low-mass
stars remain poorly constrained. The James Webb Space
Telescope (JWST) enables precise infrared studies that are highly sensitive to abundance variations in cool
stars. We initiate a homogeneous survey of
Galactic GCs, based primarily on deep JWST GO-8960 observations and complemented by archival JWST and Hubble Space
Telescope data, to characterize multiple populations across a wide range of cluster properties. In this first paper, we present the survey and initial NIRCam results. We analyze eleven GCs, deriving high-precision photometry and astrometry to measure proper motions. Multiple populations are detected among low-mass
stars in all clusters, with diverse behaviors. We find discrete main sequences in NGC 288, NGC 6723, and NGC 2808, and more continuous distributions in NGC 104 and the Type II clusters NGC 1851 and NGC 6656. The bulge clusters NGC 6528, NGC 6553, and NGC 6440 show patterns consistent with varying helium and oxygen abundances that do not scale simply with cluster mass. In Terzan 5 and Liller 1, we identify populations spanning different ages and helium variations within the old population of Terzan 5. We also detect an M-
dwarf gap in NGC 104 around 0.35
solar masses, consistent with the Jao Gap of field
stars and open clusters. This work establishes the foundation for a homogeneous JWST survey of
Galactic GCs and provides a valuable
dataset for studies of cluster
evolution,
Galactic stellar populations, and background extragalactic sources.
Read the full abstract ▾
All authors A. P. Milone, A. F. Marino, G. Cordoni, E. Dondoglio, M. V. Legnardi, T. Ziliotto, E. Bortolan, F. Muratore, F. D'Antona, A. Renzini, G. Girardi, L. Gorza, A. Mastrobuono-Battisti, C. Ventura, P. Ventura, V. Altomonte, L. Bisigello, Y. Cavecchi, F. Dell'Agli, A. Dotter, E. P. Lagioia, C. Li, S. Lionetto, A. Marchuk, J. Qi, G. Rodighiero, M. Tailo, H. Wirth
General Relativity and Quantum Cosmology
Solving Einstein Field Equations on a Digital Quantum Computer
Clelia Altomonte and Malcolm Fairbairn
In this work, we show how simulations performed on classical computers such as those of Numerical Relativity can be tackled by
quantum algorithms for solving systems of partial differential equations. We develop a proof-of-principle
quantum algorithm for solving Einstein Field Equations in the Wahlquist-Estabrook-Buchman-Bardeen(WEBB) tetrad Numerical Relativity formalism [1], and test it by evolving the Schwarzschild Black Hole spacetime in the WEBB Numerical Relativity formalism [2], perturbing it to obtain gravitational Quasinormal Modes [3]. We program the
algorithm components for a gate-based, digital
quantum computer using the Qiskit software [4] and run it on classical simulators and physical IBM
quantum computers through the UKRI National
Quantum Computing Centre (NQCC)
Quantum Access program and quantify the computational resources and runtime.
Read the full abstract ▾
Materials Science
Deciphering Noise in tip–sample Interactions: Insights into Nanoscale Dynamics
Jaime Colchero and Juan F. González-Martínez
Noise sets the fundamental limits of resolution and sensitivity in Dynamic Atomic Force Microscopy (DAFM). While thermal fluctuations are conventionally assumed to be the dominant noise source, this work demonstrates that tip–sample interactions in ambient conditions introduce a non–thermal noise component that significantly exceeds the thermal background. Using a model system of sodium dodecyl sulfate (SDS) on graphite, we characterize this noise through force spectroscopy, 3D imaging modes, and Kelvin Probe Force Microscopy (KPFM). This interaction–induced noise arises from the
stochastic formation and rupture of nanoscopic
liquid necks, serving as a direct fingerprint of local wettability and dissipative dynamics. Crucially, we find that this “noise channel” provides chemical contrast that is distinct from and complementary to the electrostatic potential mapped by KPFM. By deciphering the physical origin of these fluctuations, we establish that noise is not merely an instrumental artifact but a rich spectroscopic signal, and we propose that Frequency Modulation (FM–DAFM) offers a superior approach to decouple these dissipative effects for high–resolution imaging.
Read the full abstract ▾
Applied Physics
Fully Scalable Polarization-Reconfigurable S/X-Band Shared-Aperture Phased Array for Ultra-Low Axial-Ratio Scanning
Mohamed Räsänen, Juha Ala-Laurinaho, Samuel de Jésus Ndimubandi et al. (+8 more)
This paper presents a modular S-/X-band shared-aperture phased-array
antenna (SAPAA) for satellite-communication ground-station reception. The proposed architecture uses a repeatable unit
cell that supports independent S- and X-band operation within the same physical aperture and enables arbitrary aperture scaling. Dual-polarized radiators are combined with calibrated complex receive coefficients to synthesize linear polarization (LP), right-hand circular polarization (RHCP), and left-hand circular polarization (LHCP). The design burden of the electrically large shared aperture is reduced by using theoretical estimates for scan matching and inter-band isolation before full shared-aperture verification. Simulated and measured results demonstrate axial ratios below 0.1 dB in the target S- and X-band receiving bands over a +/-50 deg scan range. The prototypes are validated using two approaches: passive measurements, where the element responses are measured individually, and RF system-on-chip-based active measurements, where all available receive channels are measured simultaneously. The results confirm that the proposed SAPAA provides wide-angle scanning, very high polarization purity, and polarization-reconfigurable operation for multi-mission SATCOM ground terminals.
Read the full abstract ▾
All authors Mohamed Räsänen, Juha Ala-Laurinaho, Samuel de Jésus Ndimubandi, Eugenio Cano Muñoz, Xiaoliang Sun Wang, Alfonso Tomás Muriel-Barrado, Andrea Di Giovanni, Raffaele Di Bari, Marco Alessandrini, José Manuel Fernández González, Ville Viikari
Quantum Physics
Profiling the Effective Limits of Error Mitigation via Circuit Replication
Jeremie Pope and Swaroop Ghosh
Current era
quantum computers continue to grow in both capability and capacity. Despite these advancements, errors induced by environmental noise severely limit practical applicability. Current research into error mitigation and correction to bridge the gap between current-era
quantum computers and the execution of noise-sensitive workloads. These methods have significant performance and resource overheads, thereby greatly limiting the real-world benefits of their use.
Circuit replication, as a naive form of error mitigation, is not new and has largely been ignored given the resource constraints of current
quantum hardware. However, its simplicity is attractive as a means to supplement modern methods, reducing the overall performance overhead while still preserving error-mitigation capabilities. In this paper, we profile the effects of simple
circuit replication under real-world noise profiles to better establish replication's limits as a supplemental mitigation strategy.
Quantum Approximate Optimization
Algorithm (QAOA) for the Maxcut problem is explored for the analysis. For small graphs, we found that the average inference strength decreases by approximately 21.8% while the average standard deviation decreases by 108.8% compared to 6 replicates. For larger graphs, inference strength decreases by 35.4% while the average standard deviation decreased only 20.5%. Fewer replications did not affect smaller graphs, but degraded inference strength, with comparable benefits to standard deviation in larger graphs. These results show that replication has potential uses as a supplemental mitigation strategy for large-depth, highly variable workloads.
Read the full abstract ▾
Cosmology and Nongalactic Astrophysics
Loss-Cone-Limited Dark Matter Capture by Early Black Hole Seeds
Brian Zhang and Grant J. Mathews
The rapid appearance of supermassive black holes at high
redshift motivates a reassessment of non-baryonic growth channels. We develop a new loss-cone framework for collisionless dark-matter (DM) capture by early black-hole seeds, with particular
attention to phase-space depletion and refilling. The calculation combines Eddington-inverted NFW-like
halos, a relativistic direct-capture boundary, and an orbit-averaged Fokker-Planck treatment of angular-momentum transport.
Primordial black holes (PBHs) are treated as massive perturbers whose refilling strength depends on both their abundance and individual mass. Collisionless refilling by triaxial or chaotic centrophilic orbits is included as a phenomenological upper-envelope channel. We show that ordinary
stellar relaxation gives negligible DM-driven growth for the fiducial high-
redshift seeds. PBH-driven granularity can yield order-of-magnitude growth in sufficiently compact
halos, while triaxial or full-loss-cone supply can produce a rapid early burst. In the self-consistent calculations, however, the
evolution generally becomes supply-limited. Once the accessible low-angular-momentum phase-space reservoir is depleted, the capture rate collapses and the black-hole mass saturates. Fixed-background NFW calculations therefore overestimate sustained growth, especially in the full-loss-cone limit. A TNG50-calibrated NFW
benchmark gives negligible growth even under optimistic refilling assumptions. Collisionless DM capture is therefore unlikely to solve early SMBH growth in generic NFW-like
halos, but it can provide a radiatively dark upper envelope in rare compact environments with efficient angular-momentum refilling.
Read the full abstract ▾
General Relativity and Quantum Cosmology
Out-of-Equilibrium Effects in Non-Radial Relativistic Stellar Perturbations: A Model-Agnostic Formulation and Mode Analysis
Takuya Katagiri, Victor Guedes and Kent Yagi
We present a systematic, model-agnostic analysis of out-of-
equilibrium effects, including viscosity and thermal conductivity, in non-radial oscillations of relativistic
stars. Extending the Lindblom-Detweiler formalism, we construct, to our knowledge, the first general framework for linear, non-radial relativistic
stellar perturbations that incorporates generic nonequilibrium corrections to the perfect-fluid sector in both the even- and odd-parity channels. Our framework is formulated in terms of the tensorial structure and thermodynamic decomposition of generic corrections without relying on any specific constitutive relations, thereby allowing us to elucidate, at a structural level, how these effects enter the perturbation equations and contribute to
geometric deformations and fluid fluctuations. As an application, we consider the Bemfica-Disconzi-Noronha-Kovtun fluid and perturbatively investigate shifts in the frequencies and damping times of modes connected to their perfect-fluid counterparts in the limit of vanishing transport coefficients. We also identify structural features of the closed
eigenvalue problem that can give rise to additional mode families. Our formalism provides a unified framework for analyzing how different relativistic fluid theories modify the structure of non-radial
stellar perturbations.
Read the full abstract ▾
Quantum Physics · Cross-listed from cs.NI
Can Quantum Receiver Beat the SIC Limit in Multiple Access Networks?
Shiqian Guo, Huaiyu Dai and Jianqing Liu
Successive interference cancellation (SIC) is an important technique for 5G/B5G wireless receivers to resolve interfering signals from multiple users. While SIC has been proven to approach the channel capacity limit in many settings of multiple access networks, it remains unknown if this limit can be surpassed by an advanced yet practically implementable
quantum receiver technique. In this work, we answer this quest by proposing a full-stack
quantum receiver that integrates front-end
quantum sensing with back-end
quantum signal processing. The proposed technique leverages simple
qubit ensembles without using any complex
entanglement resources to parallelly extract interfering multiuser signals, with a channel capacity beyond the limit of SIC in some operational corners. In performance evaluation, we report notable
quantum advantage over the ultimate multiple-access channel capacity limit and practical SIC
algorithms in low-SNR regimes in terms of spectral efficiency and detection efficiency due to the receiver's ability to exploit
quantum correlated measurements and superposition-enabled parallel processing.
Read the full abstract ▾
Astrophysics of Galaxies
Variables in S-PLUS: I. Multiband period-luminosity relations and reddening maps of the Magellanic Clouds using classical Cepheids
Debasish Hazarika, Carlos E. Ferreira Lopes, Márcio Catelan et al. (+12 more)
Aims. Classical Cepheids (CCs) are fundamental standard candles for the extragalactic distance scale through their period-luminosity (P-L) relations. Although well calibrated in broadband systems, their behavior in narrowband filters remains poorly explored. Combining broad- and narrowband photometry can improve constraints on extinction and
dust distributions. Methods. We derived multiband P-L relations for more than 8000 CCs in the Magellanic Clouds (MCs) using Southern Photometric Local Universe Survey (S-PLUS) observations in five broad and seven narrow bands. Single-epoch magnitudes were corrected using a framework that simultaneously accounts for relative reddening and line-of-sight depth. P-L coefficients were determined through iterative fitting and maximum-likelihood optimization, with uncertainties estimated from
Bayesian Markov chain Monte Carlo analyses for both fundamental- and first-overtone-mode Cepheids. Results. We present the first Cepheid P-L relations in the S-PLUS photometric system. The relations provide consistent distance and reddening estimates across all 12 bands. Their dispersion decreases toward longer wavelengths, while the slopes vary from $\sim-2.0$ to $-2.8$ in the bluest bands and from $\sim-2.9$ to $-3.2$ in the reddest bands. The resulting reddening maps reveal strong spatial extinction variations and recover prominent structures, including 30~Doradus and the H\,I supergiant shell SGS~12 (LMC~3). The inferred orientations of the MCs is consistent with previous studies. Conclusions. Accurate distances and reddening can be recovered from single-epoch multiband photometry when combined with light-curve corrections, enabling high-precision three-dimensional mapping of the MCs.
Read the full abstract ▾
All authors Debasish Hazarika, Carlos E. Ferreira Lopes, Márcio Catelan, Felipe Almeida-Fernandes, Nicolás Rodriguez-Segovia, Vinicius M. Placco, Guilherme Limberg, Luis A. Gutiérrez-Soto, Vinicius Cordeiro, Marcelo Borges Fernandes, Pedro K. Humire, William Schoenell, Antonio Kanaan, Tiago Ribeiro, Claudia Mendes de Oliveira
Optics
Optical Two-Centered Charges, Dipoles, and Conveyor-Belt Modes in Bipolar Coordinates
J. Strohaber
We holographically generate optical modes associated with bipolar-coordinate solutions of the Helmholtz equation. Unlike conventional Gaussian beam families, these modes support multicenter phase discontinuities. We investigate and demonstrate that they support multicentered phase singularities, including optical dipoles and two-centered charge distributions. We further identify a family of conveyor-belt modes whose intensity structure follows an extended trajectory connecting the charge centers. Experimental generation using a spatial light modulator is presented and compared with theoretical predictions. These results establish bipolar-coordinate optical modes as a new class of structured light fields for singular optics, beam shaping, optical manipulation, and the controlled generation of multicentered topological structures.
Read the full abstract ▾
Mesoscale and Nanoscale Physics
Observation of Berry curvature fluctuations from incipient polar order in an oxide interface
S. Avraham, D. Gitman, P. Matus et al. (+6 more)
Diagnosing hidden local orders at buried interfaces remains a central challenge in the design and characterization of
quantum materials. Second-order electrical responses, such as the nonlinear
Hall effect, probe inversion-
symmetry-breaking terms invisible to linear transport, offering a direct window into these nanoscale environments via the
quantum geometry of Bloch electrons. Here, we utilize $\text{KTaO}_3$, a complex
oxide driven by strong tantalum $5d$
spin-orbit coupling and interfacial inversion
symmetry breaking, to demonstrate that second-harmonic resistivities exhibit large, reproducible mesoscopic fluctuations. Remarkably, these fluctuations persist in macroscopically large ($200\,\mu\text{m}$) devices and are ubiquitous across all studied surface orientations, even where macroscopic conductivity strictly adheres to underlying
crystal symmetries. We propose that these robust,
magnetic-field-driven interference patterns arise from local structural
symmetry breaking, driven by incipient ferroelectric polarization pinned to the interfacial
impurity landscape. This defect-pinned polar mechanism is firmly supported by the signal's suppression above $10\text{ K}$ due to phase decoherence, and a complete loss of mesoscopic
memory upon thermal cycling above $40\text{ K}$. By linking
quantum geometry to dynamic
lattice ordering, our findings establish nonlinear mesoscopic transport as a powerful new characterization tool, capable of revealing local polar tendencies and hidden structural orders in complex materials that remain fundamentally invisible to conventional probes.
Read the full abstract ▾
All authors S. Avraham, D. Gitman, P. Matus, S. Sandik, E. Raz, S. Jana, M. Dahan, T. Holder, Y. Dagan
Mathematical Physics · Cross-listed from math.PR
Slot decomposition of continuous Box-Ball Systems
Inés Armendáriz, Pablo Blanc, Pablo A. Ferrari et al. (+1 more)
We study a piecewise constant function $\eta:\mathbb R\to\{-1,1\}$ with a finite number of discontinuities in any interval. We assume that the associated walk $\xi:\mathbb R\to\mathbb R$ satisfying $\xi'(x)=\eta(x)$, pinned by $\xi(0)=0$, has finite length excursions over past minima. This is the continuous generalization of an initial ball configuration in the discrete Box Ball System introduced by Takahashi and Satsuma, where
solitons of integer sizes $k\ge1$ are identified. We extend the slot decomposition developed by Ferrari, Nguyen, Rolla and Wang in the discrete setting to the continuous case. Each
soliton of $\xi$ is represented by a point in two dimensional space, one coordinate for position and the other for the
soliton height, mapping $\xi$ to a point configuration. We consider a distribution on walks given by a product measure on the decomposition of the path into excursions over past minima. Excursions are distributed as products of their
solitons weights, which are determined by the
soliton heights. We show that when the weight function is in $L^1$ the slot decomposition of $\xi$ is a Poisson process. This extends to the continuous case an approach of Ferrari and Gabrielli. As an example, we compute the intensity measure of the Poisson process associated to the asymmetric telegraph process introduced by Kac. In a forthcoming paper we discuss the dynamic properties.
Read the full abstract ▾
All authors Inés Armendáriz, Pablo Blanc, Pablo A. Ferrari, Davide Gabrielli
Chemical Physics
Rothe's Method for Quantum Dynamics in Atoms and Molecules with Gaussian Wavepackets
Simon Elias Schrader, Håkon Emil Kristiansen, Aleksander P. Wozniak et al. (+3 more)
Capable of capturing both bound and continuum
quantum dynamics, Gaussian wavepackets are highly attractive basis functions for simulating
laser-driven processes in atoms and molecules. Unfortunately, fully flexible Gaussian wavepackets are exceedingly challenging to propagate in a numerically stable manner within the framework of conventional time-dependent variational principles. In this chapter, we discuss the sources of the numerical issues and review an alternative approach, Rothe's method, that offers a route to improved numerical stability. Recent proof-of-concept simulations based on Rothe's method indicate that Gaussian wavepackets provide results on par with highly accurate grid-based methods for both electronic and rovibrational
quantum dynamics, including ultrafast nonlinear processes that involve the continuum such as high-harmonic generation. Remarkably few Gaussian wavepackets are needed to achieve the high accuracy of grid-based approaches, indicating that further algorithmic developments and efficient implementations may enable efficient simulations of not only electronic and rovibrational phenomena but also fully coupled electronic-
nuclear quantum dynamics with significantly reduced
memory demands. We also point out remaining practical challenges, including
matrix elements of the squared
Hamiltonian and the treatment of Coulomb cusps.
Read the full abstract ▾
All authors Simon Elias Schrader, Håkon Emil Kristiansen, Aleksander P. Wozniak, Ludwik Adamowicz, Simen Kvaal, Thomas Bondo Pedersen
General Relativity and Quantum Cosmology
Quantum Dust from the Curse of Dimensionality
Kenan Oggad
Why do unrelated approaches to
quantum gravity nearly all find spacetime two-dimensional at the shortest scales? Each theory answers only within its own dynamics; we highlight a single kinematic route to the same value, one assuming no field equation and living in the geometry of the space of states alone. That route is concentration of measure on the Fubini-Study geometry of pure states, which forces the pairwise distances of a random sample to equalize as the dimension grows, so any finite sample collapses to an equidistant
dust whose thresholded metric graph is the complete graph. Handed this
dust, a
diffusion probe reads it as two-dimensional in the large-sample limit, the value the running spectral dimension takes at the
dust's single relaxation scale, a property of the measurement rather than the structure; this convergence on two is not, by itself, evidence that spacetime is two-dimensional. Whether a given two is such an artifact is governed by the
Laplacian spectrum near zero, and whether that reading carries across an emergence map is the condition we call spectral faithfulness; a single relaxation scale encodes no spectral dimension that tells one structure from another. The collapse, the probe value, and the
eigenvalue-density criterion are machine-checked in Lean 4 against Mathlib, resting on the standard Beta law of overlaps; a power-law tail of small
eigenvalues reads a genuine dimension, a single scale above a gap reads two at its own clock, and a gapped two-scale band reads off the universal line. These classes are run on graph-
Laplacian proxies, and whether a link-graph reading carries to the physical nonlocal operator is left open. The spectral test reads the
eigenvalue density near zero and separates, on a given structure, a measurement artifact from a dimension the structure genuinely expresses.
Read the full abstract ▾
High Energy Physics (Theory)
Dark bubbles, dark dimensions and fat gravitons
Ulf Danielsson and Suvendu Giri
The dark bubble model explains the existence of a positive cosmological constant by making explicit use of the instabilities underlying the de Sitter swampland
conjectures to make the accelerated expansion of the universe inevitable. A distinctive consequence of the construction is a unique hierarchy connecting cosmological, gravitational, string, and higher-dimensional scales. In particular, the model naturally predicts the existence of a dark dimension of micron size, an idea that has been argued for on independent grounds in the literature. The same framework also predicts a weakening of
gravity at distances of order the dark-dimension scale, leading to a fading of the gravitational force at micron distances. We argue that the dark bubble therefore provides a concrete realization of both the dark dimension proposal and Sundrum's fat graviton scenario, in which
gravity effectively ceases to probe shorter distances. Additional predictions include a string scale of order tens of TeV and a measurable positive spatial
curvature of the universe. We review these key aspects of the model, discuss their implications for
gravity and cosmology, and highlight its key predictions.
Read the full abstract ▾
Materials Science
Persistent structural distortions and absent superconductivity in trilayer nickelate thin films
Abigail Y. Jiang, Maria Bambrick-Santoyo, Lopa Bhatt et al. (+14 more)
A new family of high-temperature
superconductors was recently discovered in the $n=2,3$ Ruddlesden-Popper nickelates, where superconductivity emerges concomitant with suppression of parent density waves and structural octahedral rotations under hydrostatic pressure. Intriguingly, compressive strain mimics the structural effects of pressure in the $n=2$ phase, yielding ambient-pressure superconductivity. However, analogous strain-stabilized superconductivity has not been realized in the $n=3$. Here, we use atomically-precise synthesis, transport, picoscale electron microscopy, and synchrotron X-ray diffraction to probe $n=3$ La$_4$Ni$_3$O$_{10}$ thin films. Although compressive strain suppresses density wave order, we do not observe superconductivity even under the largest strain state. Importantly, we identify a structural distortion unique to strained $n=3$ thin films that may inhibit superconductivity: persistent, layer-inequivalent octahedral rotations around the $c$-axis. Our results highlight key differences between the $n=3$ and $n=2$ systems, suggesting that ambient-pressure superconductivity in the $n=3$ may require new methods beyond epitaxial strain engineering.
Read the full abstract ▾
All authors Abigail Y. Jiang, Maria Bambrick-Santoyo, Lopa Bhatt, Kyeong-Yoon Baek, Yi-Feng Zhao, Dan Ferenc Segedin, Ari B. Turkiewicz, Jenna Hatmin, Grace A. Pan, Suchismita Sarker, Donald A. Walko, Charles M. Brooks, David A. Muller, Berit H. Goodge, Hua Zhou, Antia S. Botana, Julia A. Mundy
General Relativity and Quantum Cosmology
Scattering, Hawking Radiation and Neutrino Energy Deposition in Euler-Heisenberg Black Holes Surrounded by Perfect Fluid Dark Matter
Ramon Becar, P. A. Gonzalez, Ali Ovgun et al. (+2 more)
We study the dynamical and scattering properties for the Euler-Heisenberg BH surrounded by perfect fluid dark matter. The geometry contains a compact non-linear electrodynamic correction governed by the EH coupling and a logarithmic dark-matter contribution governed by the surrounding PFDM
halo. We study the scalar, electromagnetic and a particular effective axial
spin-2 channel constructed on the fixed EH plus PFDM background, acting as a proxy for the gravitational-like perturbation problem and not for the fully coupled gravitational perturbation problem. We compute the quasinormal-mode spectrum employing a thirteenth-order WKB method supplemented with Padé resummation and compare it with the eikonal prediction calculated in terms of the angular frequency of the
photon sphere and the Lyapunov exponent. Moreover, we study the near-extremal configurations and derive a purely imaginary branch of quasinormal frequencies in the near-horizon region, whose damping rate increases with the PFDM parameter and is nearly
spin-independent. We then compute exact greybody factors by direct numerical integration of the radial wave equation and compare them to analytical lower bounds. We also analyze the absorption cross sections and the Hawking emission spectra. We also calculate the relativistic enhancement of the
neutrino-antineutrino annihilation channel outside the EHPFDM black hole. We find that the PFDM parameter contracts the optical structure, increases the oscillation frequency, enhances the damping rate and suppresses transmission. On the other hand, the Euler-Heisenberg correction leads to a weaker near-horizon deformation whose effect becomes relevant for sufficiently large charge. These results provide a common scattering framework for comparing the impact of dark-matter environments and nonlinear electrodynamics
Read the full abstract ▾
All authors Ramon Becar, P. A. Gonzalez, Ali Ovgun, Joel Saavedra, Yerko Vasquez
Optics
Cavity-Mediated Long-Range Cooperative Coupling between Localized Plasmons and Molecular Excitons
Livin Paul, Alona Vidishcheva, Gal Sandik et al. (+2 more)
Strong coupling between molecules and electromagnetic fields has emerged as a powerful strategy to modify the physical and chemical properties of molecules, enabled by the formation of hybridized energy levels through strong light-matter interactions. Rather than purely photonic or plasmonic modes, hybrid cavity fields that integrate plasmonic and photonic contributions provide versatile platforms with distinct advantages for tailoring light-matter interactions. Here, we present hybrid modes formed through the coupling between localized surface plasmon resonances of Au nanoparticles and Fabry-Perot microcavity modes. Furthermore, by using this hybrid platform, we demonstrate that the cavity field can give rise to cooperative coherent coupling between the spatially separated plasmonic nanoparticles and the molecules by mediating long-range dipole-dipole interactions. As we show, this cavity-mediated coupling also enhances the plasmon-
exciton mixing, as compared to their direct interaction. This configuration opens new avenues for tailoring light-matter interactions at the nanoscale by supporting novel hybrid plexcitonic states that incorporate contributions from plasmons,
excitons, and extended cavity fields.
Read the full abstract ▾
All authors Livin Paul, Alona Vidishcheva, Gal Sandik, Adina Golombek, Tal Schwartz
Quantum Physics
Unobservables and Decoherence from Complexity
Michael Epping and Jochen Szangolies
The interface between the
quantum and the classical is an intriguing and, at times, hotly contested subject of ongoing research. The
quantum regime is characterized by interference, made possible by the superposition principle, while such phenomena are absent in macroscopic, everyday experience. Here, we investigate the link of this absence (or, as we will argue, unobservability) to computational complexity. We show how the assumption that
quantum systems cannot solve NP-complete problems efficiently implies that certain formally valid
quantum measurements on finite-dimensional systems are unperformable. We study several consequences of this restriction. First, Pauli
matrices in an inconveniently transformed basis are a simple example of unobservables. Furthermore, some
quantum states are not connected by any physically realizable time
evolution. Finally there are
quantum states whose coherence cannot be observed, i.e. superpositions of pure
quantum states which are indistinguishable from mixtures. We discuss the connection of this phenomenon to the presence of superselection sectors. Our results suggest that the apparent classicality of macroscopic systems may be partly due to limitations on measurements and time evolutions imposed by computational complexity.
Read the full abstract ▾
Quantum Physics · Cross-listed from cs.IT
Learning-Based List Sequential Belief Propagation Decoding of Quantum LDPC Codes
Mohsen Moradi, Taejoon Kim and Remi A. Chou
Quantum low-density parity-check (QLDPC) codes are strong candidates for fault-tolerant
quantum computation, but efficient decoding remains a major challenge due to short cycles, degeneracy, and the poor convergence of standard belief-propagation (BP) decoders. We propose a reinforcement learning-based list sequential (RL-LS) BP decoder for QLDPC codes by extending the reinforcement-learning-based sequential variable-node scheduling (RL-S) framework with list-based search. At each step, the learned policy selects the next variable node to update; the decoder then retains the ordinary RL-S trajectory while also exploring a competing branch obtained by softly biasing the post-update LLR pair toward the second-most likely Pauli symbol, recomputing the incident local BP messages, and setting the visited variable node to that second-best symbol. Candidate trajectories are ranked and pruned using our proposed cumulative path metric. The resulting decoder extends the learned decoder by combining the improved convergence of learned sequential scheduling with list exploration. Numerical results on representative QLDPC
benchmark codes over the depolarizing channel show that our proposed method improves the decoding performance of the underlying decoder and compares favorably with existing BP-based decoding methods.
Read the full abstract ▾
High Energy Physics (Phenomenology)
Event-Level QCD Inference Framework for Quark-Gluon Imaging
Patrick Barry, Pi-Yueh Chuang, Ian Cloët et al. (+3 more)
We introduce and demonstrate an event-level analysis framework for
quark-
gluon imaging. For a first application we use it for the inference of parton distribution functions from synthetic deep inelastic scattering data. This framework removes the need for unfolding of detector effects and the binning of events, and therefore eliminates two key sources of information loss. We contrast this event-level framework with the traditional histogram approach by performing a closure test for parton distribution functions from event data obtained from a known ground truth. In this study we assume a perfect detector, which makes unfolding straightforward. The elimination of binning in the event-level framework is demonstrated to have important benefits over the traditional histogram approach, and performs better in the closure test, particularly for a smaller number of events. For example, defining a mean-squared error distance metric, we find that the event-level framework performs around $35\%$ better than the traditional approach for a moderate number of events. The benefits of an event-level framework should increase for inference associated with 3D
quark-
gluon imaging, because these differential cross sections are of higher dimension and the comparative number of measured events is significantly reduced.
Read the full abstract ▾
All authors Patrick Barry, Pi-Yueh Chuang, Ian Cloët, Emil Constantinescu, Arkaprabha Ganguli, Chao Peng
Soft Condensed Matter
Quantum Enhancement of Particle-Size Segregation
Tomás Trewhela
Segregated states based on particle size emerge in granular materials from the competition between segregation and diffusive remixing. Here, we show that
quantum coherence can enhance segregation beyond this classical limit. We introduce an open
quantum cellular automaton for bidisperse mixtures that combines coherent transport and dissipative segregation. The automaton reproduces experimental and continuum-theory segregation dynamics, with segregation degrees collapsing onto a theoretical Péclet-dependent relationship. However, weakly decohering systems exhibit a coherence-driven transport regime that produces more strongly segregated steady states than classical predictions. Across a broad parameter range, the steady-state degree of segregation collapses onto two dimensionless numbers governing the competition between segregation,
diffusion, and decoherence. These results identify
quantum coherence as a mechanism for enhancing particle-size segregation and establish a framework for studying transport phenomena in open many-body systems.
Read the full abstract ▾
Computational Physics · Cross-listed from cs.MS
NektarIR: A Domain-Specific Compiler for High-Order Finite Element Operations on Heterogeneous Hardware
Edward Erasmie-Jones, Giacomo Castiglioni and David Moxey
Modern high performance computing (HPC) applications must target heterogeneous hardware. This requires significant work to ensure domain specific implementations translate to highly performant kernels across a range hardware types and vendors, each requiring bespoke optimization to make use of the specific target architecture. Through the development of a domain specific compiler built with the multi-level intermediate representations (MLIR) project, one can express a high-level, close to the specific domain, abstraction that is progressively lowered to a low, close to metal, abstraction. At each intermediate representation (IR), appropriate optimizations can be applied without costly analysis due to the knowledge embedded in the domain specific IRs. We apply this method to the construction of discrete differential operators for use in spectral/hp element method solvers for computational fluid dynamics (CFD). Here, the performance is driven by a small set of common finite element operators that are composed to create kernels for the discrete differential operators used to solve weak partial differential equations. We create our own MLIR dialect to represent these operators and implement a bespoke lowering pipeline to facilitate the just-in-time compilation of these kernels for both CPU and GPU architecture and illustrate performance comparisons with the Nektar++ spectral/hp element framework.
Read the full abstract ▾
High Energy Physics (Theory)
Renormalization effects fade away during inflation
Christian Durán Romero, Luis J. Garay, Mercedes Martín-Benito et al. (+1 more)
The renormalization of the
primordial inflationary power spectrum has long raised the possibility that ultraviolet effects could significantly alter predictions for cosmological observables. We demonstrate that inflation dynamically suppresses the entire renormalization sector: while super-Hubble perturbations freeze after horizon crossing, renormalization contributions decay rapidly during inflation. As a consequence, the observable
primordial spectrum is remarkably insensitive to renormalization ambiguities, providing strong evidence for the robustness under renormalization of standard inflationary predictions at observable scales.
Read the full abstract ▾
All authors Christian Durán Romero, Luis J. Garay, Mercedes Martín-Benito, Rita B. Neves
Optics
Experimental Investigation of Surface Passivation Chemistries for Optical Nanotweezers
Maxwell T. Ugwu, Kewei Li, Abayomi Opadele et al. (+2 more)
Nanotweezers are actively investigated as a powerful means to reversibly trap and characterize nanoparticles with profound biological and environmental importance. To ensure that these particles can be reversibly trapped and released, surface passivation is essential. To mitigate the issue of fouling, we investigated the antifouling properties of poly(sodium styrene sulphate) (PSS) synthesized using the Atom Transfer Radical Polymerization (ATRP) technique on our previously reported gold-based Interferometric Electrohydrodynamic Tweezers (IET) device. Fluorescence and interferometric scattering (ISCAT) imaging were used to record trapping performance and study the antifouling properties of our passivated nanotweezer device. The results show that PSS exhibits superior anti-fouling performance against polystyrene nanoparticles when compared to 11-mercaptoundecanoic acid (MUA). By comparing the antifouling properties of PSS and zwitterionic poly(methacryloyloxyethyl phosphorylcholine) (PMPC) in preventing extracellular vesicle adhesion, we found that both exhibited similar performance. Overall, the ATRP technique is broadly applicable across nanotweezer substrates with appropriately chosen initiators.
Read the full abstract ▾
All authors Maxwell T. Ugwu, Kewei Li, Abayomi Opadele, Theodore Anyika, Justus C. Ndukaife