Materials Science
Structure-Agnostic Prediction of the Electronic Density of States with a Chemical Language Model
Ivan D. Rubtsov, Ivan V. Dudakov and Vadim V. Korolev
The electronic density of states (DOS) is conventionally computed from a relaxed
crystal structure, which is unavailable for compounds that have been neither synthesized nor cataloged. Here we introduce DOSSIER ($\textbf{D}$ensity $\textbf{o}$f $\textbf{S}$tates from $\textbf{S}$to$\textbf{i}$chiometry with $\textbf{E}$ncoder $\textbf{R}$epresentations), a chemical
language model that maps elemental composition directly to this spectrum. The encoder is pretrained by cross-modal knowledge
distillation from a universal machine-learning interatomic potential; the transfer lowers the error by 11% when only 1,000 training examples are available. On the Mat2Spec
benchmark, DOSSIER reaches a mean absolute error of 3.76 states eV$^{-1}$ against 3.64 for the best structure-aware model; on an extended Materials Project
dataset, the predicted spectra yield band gaps and $\textit{d}$-band descriptors with useful accuracy. Screening 11,977 binary and 13,251 five-component high-
entropy alloy compositions for a $\textit{d}$-projected DOS resembling that of NiPt$_{3}$ places known oxygen reduction electrocatalysts near the top of the ranking.
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Mathematical Physics
Bound State Analysis of Rank-One Delta Interactions Supported by Deformed Hyperspheres
Hilal Demirdöğen, Fatih Erman and Merve Nur Sayar
We study rank-one delta interactions supported by small normal deformations of an \(n\)-dimensional hypersphere \(S_R^n\subset\mathbb{R}^{n+1}\). The interaction is defined by the normalized surface measure on the support and therefore corresponds to the rotationally invariant sector of the hyperspherical shell problem. For the undeformed hypersphere, we derive the bound-state equation for \(E=-\nu^2\) in terms of the modified Bessel product \[ I_{\frac{n-1}{2}}(\nu R)K_{\frac{n-1}{2}}(\nu R). \] We then consider an inward normal deformation \[ X_\varepsilon(\omega)=(R-\varepsilon h(\omega))\omega, \qquad \omega\in S^n, \qquad 0<\varepsilon\ll1. \] Our main result is that, to first order in \(\varepsilon\), the bound-state energy depends only on the average normal displacement \[ \langle h\rangle = \frac1{|S^n|}\int_{S^n}h(\omega)\,d\Omega_n(\omega). \] Equivalently, the deformed hypersphere is spectrally equivalent, up to \(O(\varepsilon^2)\), to a round hypersphere with effective radius \(R-\varepsilon\langle h\rangle\). In particular, mean-zero deformations do not change the rank-one bound-state energy at first order.
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Quantum Physics
Quantum simulation of circular cluster interactions in a linear spin chain
Alexander van Lomwel, Hongzheng Zhao and Florian Mintert
The preparation of ground states of
Hamiltonians with
symmetries that are fundamentally different than those of the underlying device is a central challenge for
quantum technologies. Here, we address this challenge with an analog protocol for the iconic generalized cluster
Hamiltonian with the translational
symmetry resultant from periodic boundary conditions based on a magnetization-preserving interaction on a linear geometry with open boundary conditions. Our results show that this goal can be achieved in a control duration that scales only moderately with the number of
spins and
Hamiltonian interaction complexity.
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Nuclear Experiment
Cluster emission and its impact on the r-process nucleosynthesis
Natalia Thomas, Silvia Bara, Thomas Elias Cocolios et al. (+20 more)
Cluster emission is an exotic decay mode between alpha-decay and fission, in which a parent
nucleus emits a cluster of nucleons heavier than an alpha-particle, but lighter than what is usually considered a fission fragment. The properties of cluster emission were investigated by analyzing five high-energy events detected in a spectrum of a mass A = 230 beam produced at ISOLDE (CERN). Under the assumption that these events were caused by cluster emission, the most likely parent-cluster pair responsible for the five high-energy events, was found to be $^{230}Ra$ emitting $^{22}O$, with a branching ratio of $(4.3$ +\- $1.9) \times 10^{-9}$. Four analytical formulas were used to estimate the partial half-lives of cluster emission for a group of
neutron-rich
nuclei. The decay rate was calculated for a selection of cluster
nuclei for each parent isotope. The rates of all decay channels of cluster emission per parent
nucleus were then included in calculations of the r-process nucleosynthesis in a
neutron star merger in order to study the possible impact of cluster emission on the r-process
nuclear production. The resulting isotopic abundance distributions were compared to those calculated for a case in which cluster emission was not considered. It was found that the inclusion of cluster emission decay rates from the simple analytical formulas available nowadays does not influence the results of the r-process nucleosynthesis.
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All authors Natalia Thomas, Silvia Bara, Thomas Elias Cocolios, Stephane Goriely, Boris Andel, Andrei N. Andreyev, Alberto Camaiani, James G. Cubiss, Hilde De Witte, Zoe Favier, Michael Heines, Fedor Ivandikov, Jake D. Johnson, Jozef Klimo, Razvan Lica, Jozef Mišt, Chris Page, Riccardo Raabe, Adam Sitarčík, Viktor Van Den Bergh, Piet Van Duppen, Zixuan Yue, Ahmed Youssef
Optics
AlGaAs nanowires as a universal platform for GaAs, InGaAs, and InAs quantum dots
Rohan Radhakrishnan, Rodion Reznik, Gilles Patriarche et al. (+5 more)
Optical
quantum dots (QDs) are central to photonic
quantum technologies, with fabrication approaches tailored to different spectral ranges. A key challenge, however, is the realization of a unified platform$\unicode{x2014}$a single growth method combined with a host material offering a designable architecture$\unicode{x2014}$enabling wavelength tunability across the full emission range and co-integration of multiple
quantum dots. Here, we introduce AlGaAs nanowires as a universal host for GaAs, InGaAs, and InAs QDs. Building on our previous demonstration of high-quality GaAs QDs, we realize InGaAs QDs with tunable emission by varying the growth duration from 2 to 5 s, achieving emission at 780 and 920 nm. We further showcase the platform's versatility for multi-
quantum-dot devices by co-integrating two InGaAs QDs, as well as GaAs and InGaAs QDs within a single nanowire. Finally, we initiate a first step toward pure InAs QDs by growing a pristine InAs segment on AlGaAs nanowires, demonstrating material compatibility.
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All authors Rohan Radhakrishnan, Rodion Reznik, Gilles Patriarche, Igor Ilkiv, Konstantin Kotlyar, Anna Andreeva, George Cirlin, Nika Akopian
Quantum Physics
Optimal Quantum Algorithm for Ground-State Energy Estimation with a Guiding State
Stacey Jeffery and Freek Witteveen
In the problem of ground-state energy estimation, one aims to estimate the smallest
eigenvalue of a
Hamiltonian, often given a guiding state, with some promised overlap $\gamma$ with the ground space. The main approach to this problem is to simulate its
evolution, and estimate the smallest (or equivalently, largest) eigenphase of the resulting
unitary $U$. We give a
quantum algorithm that estimates the largest eigenphase of a
unitary $U$ in this guided setting using a factor of $\log\frac{1}{\gamma}$ fewer queries to $U$ than the previous best approach. The result matches an existing lower bound, and answers an open question from Mande and de Wolf. The
algorithm is based on transducers, which often allow composition of
quantum algorithms without overhead from error reduction.
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Quantum Physics
Optimal Lower Bound for Ground-State Energy Estimation with a Guiding State
Rolando D. Somma and Ronald de Wolf
Suppose we can apply the
unitary $U=e^{i H}$ for some
Hamiltonian $H$, and are given access to a
unitary that prepares a guiding state promised to have overlap at least $\gamma >0$ with the ground space of $H$. Our goal is to estimate the ground-state energy of $H$ within additive error $\delta > 0$ and success probability at least $1-\varepsilon$, $\varepsilon>0$. How many applications of $U$ and its inverse $U^{-1}$ are necessary and sufficient? This quantity corresponds to the total
Hamiltonian-simulation time needed. An upper bound $O(\log(1/\varepsilon)\log(1/\gamma)/\gamma\delta)$ was known, and was improved to $O(\log(1/\varepsilon)/\gamma\delta)$ very recently [JW26]. A matching lower bound was known whenever one of the three parameters $\delta,\gamma,\varepsilon$ was held constant [MdW26]. In this paper we prove the joint lower bound $\Omega(\log(1/\varepsilon)/\gamma\delta)$ with the tight $\varepsilon$-dependence provided the dimension of $H$ is at least $\log(1/\varepsilon)/\gamma^2$. Furthermore, we show that this same lower bound (with slightly larger dimension) holds for both the special case in which the ground state is guaranteed to be unique and $H$ has a gap of $\delta$ between its first and second
eigenvalue; and for ground-state preparation, where $\delta$ denotes the spectral gap and $\varepsilon$ now is the approximation error. The lower bounds also apply when the
Hamiltonian can be accessed via its block-encoding, and when fractional powers of $U$ are allowed, as in continuous-time
Hamiltonian simulation. Lastly, improved upper bounds are known when $H$ is nonnegative and presented as a sum of squares; and our results imply the lower bound $\Omega(\log(1/\varepsilon)/\gamma\sqrt{\delta})$ for this case.
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General Relativity and Quantum Cosmology
Non-minimally coupled Weyl connection gravity in the Solar System and at the Galactic Center
Mohsen Khodadi, Margarida Lima and Cláudio Gomes
We explore the phenomenological viability of non-minimally coupled Weyl connection
gravity by confronting its static, spherically symmetric black hole solutions with classical weak-field
Solar System tests and
stellar-orbit observations near Sgr A*. In this
geometric framework, non-metricity is encoded via a Weyl vector field, giving rise to two distinct families of Schwarzschild-like
vacuum solutions characterized by a free parameter \(\omega\) with dimensions of length. We compute the corrections to four classical observables—gravitational
redshift, Mercury's perihelion advance, light deflection, and radar echo delay—and derive stringent lower bounds on \(\omega\) using current observational data. For Solution I (purely radial Weyl vector), the leading metric corrections scale as \(1/\omega\), yielding bounds as strong as \(\omega \gtrsim 10^{30}\) m from perihelion precession. For Solution II (time-radial Weyl vector), the corrections scale as \(1/\omega^2\), resulting in weaker constraints, with \(\omega \gtrsim 10^{20}\) m from the same test. This marked difference arises from the distinct behavior of the linear corrections in each solution: while Solution I exhibits an unsuppressed linear term \(2r/\omega\) that dominates in the
Solar System regime, Solution II features a linear term suppressed by an additional factor of \(M/\omega\), making the quadratic term \(-r^2/4\omega^2\) dominant throughout. We then analyze
stellar orbits near the
Galactic Center, finding that current observations of the S2
star provide complementary constraints on both solutions. (...)
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High Energy Astrophysical Phenomena
Probing the Three-Dimensional Structure of a Jet with Faraday Tomography
Sawera Gull, Masaya Kurogi and Keitaro Takahashi
Magnetic fields play a fundamental role in the dynamics and radiation of jets associated with active
galactic nuclei (AGNs), where they accelerate and collimate the relativistic
plasma and produce the observed synchrotron emission. Faraday
tomography is a powerful technique for probing the three-dimensional distribution of
magnetic fields and synchrotron-emitting
plasma along the line of sight, by reconstructing the Faraday Dispersion Function (FDF) from the observed polarization spectrum. To explore what aspects of AGN-jet structure can be revealed by Faraday
tomography, we construct a simple three-dimensional model of an AGN jet that captures its essential features, and compute the resulting FDF for a range of model parameters. The jet is represented as a cylindrical region of uniform thermal-electron density threaded by a coherent helical
magnetic field, to which a random turbulent component can optionally be added. The parameters varied include the inclination angle {\theta} between the jet axis and the line of sight, the wavenumber of the helical field, and the amplitude of the random
magnetic-field component. By systematically varying these parameters, we examine how the underlying
magnetic geometry and
turbulence are encoded in the observable Faraday and polarization structures. The main observational signatures identified by our model include top-bottom asymmetry across the jet, curved or double peaked FDF profiles and increasingly fragmented Faraday depth structure along longer lines of sight, providing potential diagnostics of large scale helical
magnetic fields and small scale turbulent components. These signatures providing a physical framework for interpreting future polarimetric observations of AGN jets from instruments such as LOFAR, MeerKAT, and the VLA.
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Quantum Physics
Optimal copy complexity of quantum state cloning
Sangwoo Jeon, Vaughn Sohn and Changhun Oh
Quantum state cloning is the task of approximately producing additional copies of an unknown
quantum state from a finite number of input copies. The optimal cloning fidelity is known exactly for pure states, but no comparable characterization is known for general mixed states. We determine the optimal asymptotic copy complexity for $d$-dimensional states of rank at most $r$: producing $M$ additional copies with worst-case fidelity at least $1-\varepsilon$ requires and is achievable with $N=\Theta(Mrd/\varepsilon)$ input copies. Remarkably, the lower bound already holds for a family of states with a fixed flat spectrum, while the matching upper bound is achieved by random purification followed by optimal pure-state cloning. For $M=1$, we further show that high-fidelity
tomography can be coherently converted into cloning with comparable error, revealing an operational origin of the matching cloning and
tomography complexities.
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Disordered Systems and Neural Networks
Disorder-induced conducting edges on Kagomé lattice
A. Chmeruk, D. Jones and L. Chioncel
Within a cluster extension of the coherent potential approximation, disorder averaging generates a non-local self-energy that renormalizes both diagonal and off-diagonal hopping terms of the non-interacting Kagome-
lattice Hamiltonian. These renormalizations (of both nearest- and next-nearest-neighbor hopping amplitudes) drive the system between two topologically trivial insulating states through an intermediate gapless phase characterized by conducting edge modes over a broad range of
impurity concentrations. Our results demonstrate that multiple-scattering effects alone can generate emergent effective
spin-orbit interactions and qualitatively modify the edge spectrum of disordered Kagome systems.
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Materials Science
Plastic Relaxation without Dislocations in $\beta$-Ga$_2$O$_3$ Heteroepitaxy: A Structural Peculiarity of Ga$_2$O$_3$ Polymorphs
I. Bertoni, A. Marzegalli, A. Ugolotti et al. (+3 more)
$\beta$-Ga$_2$O$_3$ grows as three-dimensional islands on mismatched c-plane sapphire, often on a thin $\alpha$-Ga$_2$O$_3$ wetting layer, and eventually forms a continuous film by island coalescence. Experiments reveal the $\beta$ film to be relaxed. Surprisingly no dislocations are observed, suggesting an unusual plastic relaxation path. We reveal the key mechanisms underlying this process by combining density functional theory, continuum nucleation theory, and molecular dynamics simulations. Plastic relaxation occurs through rearrangement of the Ga atoms beneath the oxygen plane shared by both the wetting layer and the (-201) $\beta$-Ga$_2$O$_3$ structures. A local $\alpha$ to $\beta$-relaxed phase transition is thus realized within a single plane, allowing full relaxation of the $\beta$-Ga$_2$O$_3$ island.
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All authors I. Bertoni, A. Marzegalli, A. Ugolotti, R. He, F. Djurabekova, L. Miglio
Strongly Correlated Electrons
Anomalous magnetocaloric effects in the quasi-one-dimensional antiferromagnet BaCo$_2$V$_2$O$_8$
Jiahao Yang, Chao Dong, Xinlong Shi et al. (+8 more)
We investigate the transverse-field thermodynamics of the quasi-one-dimensional Ising-like antiferromagnet BaCo$_2$V$_2$O$_8$, whose tilted screw-chain geometry and anisotropic Landé $g$ tensor generate spatially modulated Zeeman couplings. Angle-resolved magnetocaloric-effect (MCE) measurements reveal a high-field temperature minimum near the transverse-field Ising critical field for $H\parallel[110]$ that persists and shifts only weakly upon field rotation. Tensor-network calculations show that the rotation-induced staggered transverse field rapidly lowers the Ising critical field and that the
magnetic Grüneisen ratio changes sign near the high-field temperature minimum, consistent with experiment. Our results establish that a dominant MCE response can persist away from the Ising critical region, suggesting a route to
magnetic cooling by tailoring anisotropic Zeeman-coupling configurations in
quantum magnets.
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All authors Jiahao Yang, Chao Dong, Xinlong Shi, Zhuo Wang, Tiantian Li, Liusuo Wu, Junfeng Wang, Zhangzhen He, Liang Li, Yongkang Luo, Jianda Wu
Instrumentation and Methods for Astrophysics
A high-isolation wideband channelizer for MKID readouts: a custom HLS implementation on RFSoC
Alberto Hernandez Fernandez, David Diaz Martin, Jose Javier Diaz Garcia et al. (+4 more)
We present a high-performance channelizer for Microwave Kinetic Inductance Detectors (MKIDs), designed to mitigate spectral leakage and scalloping loss through a 50% overlapping polyphase filter bank (PFB). The design is implemented on a Xilinx Zynq UltraScale+ RFSoC ZCU111 using a custom design - primarily in Vitis High-Level Synthesis (HLS), with the time-critical output serializer and glue logic in VHDL - that processes a 4.096 GSPS input stream with a per-branch super-sample rate (SSR) of 16. Rather than relying on aggressive 512 MHz clocking and vendor IP cores, our split-path architecture computes the delayed and non-delayed polyphase branches concurrently, so that the bulk of the channelizer operates at a robust 256 MHz while a single 512 MHz subdomain is confined to the BRAM-to-FFT section. This architectural parallelism enables a deep 16-tap prototype filter that doubles the filter depth of comparable high-speed systems and substantially improves channel isolation. We report the complete internal architecture of the reordering engine that implements the overlap, including two implementation hazards not documented in prior art: a pipeline-stage skew affecting state toggles in HLS, and the state-preservation requirements of a restartable design. The 2/1 overlapped channel response is validated in simulation - recovering the ~3.9 dB scalloping loss of a critically sampled channelizer to below 0.1 dB across the full 2 MHz channel - and characterized systematically with a 100-tone batch frequency sweep, while the parent readout system has been operated cryogenically with an MKID array in an adiabatic demagnetization refrigerator (ADR), identifying individual resonators in total darkness. The result is a resource-efficient, high-isolation
benchmark for wideband frequency-division-multiplexed readouts.
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All authors Alberto Hernandez Fernandez, David Diaz Martin, Jose Javier Diaz Garcia, Roger John Hoyland, Luis Fernando Rodriguez Ramos, Diego Portero Rodriguez, Silvestre Rodriguez Perez
Space Physics
Comprehensive solar eruption analyses enabled by the tools of the SOLER project
Nina Dresing, Jan Gieseler, Markus Baumgartner-Steinleitner et al. (+26 more)
Solar eruptions comprise of a multitude of phenomena such as
flares, coronal mass ejections (CMEs), large-scale coronal waves,
radio bursts, and energetic particles traveling through interplanetary space. These phenomena are observed with a variety of instrumentation, including remote sensing and in-situ detectors. Obtaining a global understanding of a
solar eruption often requires the analysis of various of these different
datasets, including a multitude of analysis and modeling tools and a wide range of expertise. Usually, such a comprehensive analysis can only be achieved by a skilled and broad team. The Energetic
Solar Eruptions: Data and Analysis Tools (SOLER) project aims at creating a comprehensive analysis platform for the study of
solar eruptions that allows a single user to easily apply analysis methods addressing various counterparts of the
solar event. Therefore, each partner of the project developed Python-based software, including interfaces in the form of Jupyter Notebooks, which provides application examples and concise step-to-step documentation. In this paper we introduce the comprehensive
solar-eruption-analysis infrastructure developed within the SOLER project. We explain where to find the software, how to use it, and give dedicated use-case examples of how to employ selected tools in a combined manner.
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All authors Nina Dresing, Jan Gieseler, Markus Baumgartner-Steinleitner, Carine Briand, Karin Dissauer, Annamaria Fedeli, Robert Jarolim, Jaclyn T. Lang, Diana E. Morosan, Jake A. J Mitchell, Christian Palmroos, Jens Pomoell, Jinge Zhang, Otso Santala, Astrid M. Veronig, Laura Vuorinen, Alexander Warmuth, Oliver Flor, Myrthe Flossie, Emilia K. J. Kilpua, Werner Pötzi, Daniel J. Price, Antonio Gomes, Emil J. Hotti, Ruth A. Hyndman, M. Liebel, Amaia Razquin, Song Tan, Ramio Vainio
Cosmology and Nongalactic Astrophysics
CMB Birefringence from Axion String Networks Calibrated to an AMR Simulation
Mustafa A. Amin, Mudit Jain, Andrew J. Long et al. (+3 more)
A cosmological network of
axion strings may exist in the Universe today. If
axion-like particles couple to electromagnetism, such a network induces spatially varying birefringence in the polarization of the
cosmic microwave background (CMB), which can be probed by current and next-generation CMB experiments. We calibrate a loop-crossing model against a large-scale adaptive-mesh-refinement (AMR) simulation of
axion-string network dynamics in the early Universe and use the calibrated model to predict CMB birefringence from recombination to today. We find that the non-detection of anisotropic birefringence in CMB observations places a strong upper bound on the electromagnetic anomaly coefficient $\mathcal{A}$ that enters the
axion-
photon coupling $g_{a\gamma\gamma} = - \mathcal{A} \alpha_\mathrm{em} / \pi f_a$. A joint analysis of available anisotropic birefringence measurements constrains $|\mathcal{A}| < 0.24$ at 95% C.L., which is independent of the Peccei-Quinn scale $f_a$, assuming that the
axions are hyperlight so that the network survives until today. This limit strongly restricts the high-energy
embedding of hyperlight
axions, excluding the minimal Grand Unified Theory prediction for the electromagnetic anomaly coefficient at high significance. In addition, we discuss the implications of an
axion-string origin for the recently reported evidence of isotropic birefringence.
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All authors Mustafa A. Amin, Mudit Jain, Andrew J. Long, Aden Pugsley, Moira Venegas, Magdalena Whelley
Mesoscale and Nanoscale Physics
Electronic cooling of a TiW alloy normal-metal island using Nb-based superconducting tunnel junctions
Joel Hätinen, Renan Pires Loreto, Arvind Kumar et al. (+2 more)
TiW thin films remain non-superconducting down to millikelvin temperatures and are compatible with large-scale CMOS manufacturing, making them attractive for cryogenic and
quantum tunnel-junction devices, such as normal-metal-
insulator-
superconductor (NIS) thermal sensors and electron refrigerators. We demonstrate significant electronic cooling of a TiW-based normal-metal island and electron thermometry by using TiW-Al-AlOx-Nb NIS tunnel-junction stacks. The NIS thermometer enables local electron temperature measurements from 0.5 to 8.32 K. NIS cooling is observed between 0.6 and 3.5 K, with maximum absolute and relative temperature reductions of 217 mK and 27%, respectively. Calculations using tunnel-junction parameters obtained independently from current-voltage fits reproduce the measured optimum-voltage scale, which lies substantially below the ideal low-temperature prediction.
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All authors Joel Hätinen, Renan Pires Loreto, Arvind Kumar, Jani Taskinen, Mika Prunnila
Mathematical Physics · Cross-listed from math.DS
Unstable Manifolds for the Kuramoto Model: Convergence to the Ott-Antonsen Manifold
Christian Kuehn and Giacomo Landi
In this paper, we study the finite-dimensional, homogeneous, all-to-all coupled Kuramoto model. We begin by performing a complete spectral analysis of all
equilibria of the system. Motivated by this analysis, we then derive an explicit description of the unstable
manifolds associated with the family of incoherent
equilibria. Subsequently, we establish the convergence of this family of unstable
manifolds to the Ott-Antonsen
manifold $\mathcal{M}_{\mathrm{OA}}$, with respect to the Hausdorff distance induced by the $p$-Wasserstein metric. We further carry out an analogous analysis for the corresponding counterpart of $\mathcal{M}_{\mathrm{OA}}$ in the continuum limit. Moreover, we establish the uniform-in-time convergence of trajectories of the finite-dimensional Kuramoto model on these invariant
manifolds towards their corresponding mean-field limit trajectories. Our results provide a direct
geometric link between finite-dimensional particle systems and their mean-field, or continuum, limits.
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Quantum Physics
Tunable-Size Unruh-DeWitt Detector in a Multimode Cavity
Simon Brunner, Farokh Mivehvar, Helmut Ritsch et al. (+1 more)
Quantum simulators based on Bose-Einstein condensates (BECs) provide a powerful platform to study relativistic
quantum-field phenomena in the lab and in particular emulate relativistic analog particle detectors. However, such detectors typically couple to excitations beyond the acoustic
phonon regime, so that the nonlinear Bogoliubov dispersion introduces corrections that cause the effective relativistic description to break down. We propose to overcome this limitation using an intrinsically momentum-selective Unruh-DeWitt detector model in which a tweezer-trapped atom couples to the condensate through a multimode optical cavity. Although the atom is effectively pointlike, the cavity-mediated interaction kernel causes it to sample density fluctuations over a controllable finite region of the BEC equivalent to a finite-size detector. The effective detector size is tunable via the cavity mode structure determining a controllable momentum cutoff that filters out nonphononic excitations. We analytically calculate the response of such a detector for uniform linear acceleration and uniform circular motion and show that this momentum selectivity can enhance the signal at experimentally accessible accelerations. Compatible with existing cavity-QED platforms our scheme thus provides a versatile setting for analog
quantum-field measurements or relativistic
quantum-information protocols.
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All authors Simon Brunner, Farokh Mivehvar, Helmut Ritsch, Arkadiusz Kosior
High Energy Physics (Theory)
Real-time thermal self-energies: In the variational bases and spaces
M. A. A. Ahmed, H. Zainuddin and N. M. Shah
In this work, we introduce a systematic study for studying the scalar propagator and tadpole self-energy by considering an arbitrary parameter $\sigma$ that allows for a path integral description in real-time formalism (RTF). The closed time path formalism (CTP) and Thermofield Dynamics (TFD) are two popular choices for the parameter $\sigma$ in the Feynman rules. We have constructed a scalar propagator and a tadpole self-energy in two different bases in the momentum space as well as the mixed space. The results show that the diagonal components of self-energy in both spaces for the 1/2 basis are the same in both approaches within RTF, whereas the other off-diagonal components of self-energy are different because they depend on the path parameter. On the other hand, the diagonal components of self-energy in both spaces for the new basis are not the same in both approaches within RTF, whereas the off-diagonal components of self-energy are vanishing. That means the new basis allows one to reduce the components for the quantities studied, like self-energy or other.
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High Energy Physics (Theory)
Dynamical Tidal Response and Love Numbers of Massless Bosonic and Fermionic Perturbations of Kerr–Anti-de Sitter Black Holes
Himanshu Buragohain and Prabwal Phukon
We examine the
tidal response of Kerr–Anti-de Sitter black holes using the Teukolsky formalism in a
vacuum background. We consider massless perturbations with
spin weights $s = 0,\ \pm\frac{1}{2},\ \pm1,\ \pm\frac{3}{2},\ \pm2$, corresponding to scalar, fermionic, electromagnetic, and gravitational perturbations, respectively. We determine the
Tidal Love number using the near-horizon approximation. For asymptotically flat black holes in general relativity, the conservative
tidal response vanishes identically. In contrast, we find that the presence of a negative cosmological constant parameter in the Kerr–Anti-de Sitter black holes leads to a non-trivial
tidal response, containing both conservative and dissipative contributions. We systematically study the static and dynamical
tidal responses of Kerr–Anti-de Sitter black holes. In particular, we examine the behaviour of the conservative and dissipative response coefficients and investigate their dependence on the black-hole rotation parameter and the AdS
curvature scale.
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Instrumentation and Methods for Astrophysics
Forward modelling coronagraphic images with a fully physical, differentiable digital twin of MagAO-X: first laboratory results
Matthijs Mars, Sebastiaan Y. Haffert, Louis Desdoigts et al. (+10 more)
Post-processing of high contrast imaging data relies on an accurate model of the
stellar point spread function (PSF). Current techniques build this model from the science images themselves, using observational diversity (e.g., angular, spectral or polarimetric diversity), which can cause self-subtraction of the companion signal and constrains the observing strategy. Telemetry-based forward modelling instead builds the
stellar PSF model from wavefront sensor data that is already recorded during the observation. The wavefront sensor measures the coherent starlight and can therefore be used to create a PSF model that only models the
stellar light and does not reproduce the incoherent light of a companion. We present a fully physical and differentiable digital twin of the focal plane low-order wavefront sensor (FLOWFS) and the coronagraphic science beam of the MagAO-X instrument, implemented in dLux, and calibrate it on laboratory data. When fitted directly to the science images, the model reproduces the coronagraphic PSF down to the
photon and read noise floor of the data. When instead forward modelled from the FLOWFS telemetry alone, the residuals reach $6\times10^{-5}$ of the
stellar peak at $5\ \lambda/D$, a factor of 5 below the raw contrast, with the remaining residual set by how well the wavefront estimate transfers from the FLOWFS branch to the science branch of the model. An injected companion at $5\ \lambda/D$ with a peak contrast of $10^{-3}$ is recovered without measurable self-subtraction. We discuss the model improvements currently under development and the path towards on-sky validation.
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All authors Matthijs Mars, Sebastiaan Y. Haffert, Louis Desdoigts, Joseph D. Long, Rico Landman, Jared R. Males, Laird M. Close, Kyle Van Gorkom, Olivier Guyon, Alexander D. Hedglen, Sandrine Juillard, Jennifer Lumbres, Lauren Schatz
Instrumentation and Methods for Astrophysics
NEXT: The Netherlands EXoplanet Testbed I. Goals and opto-mechanical design
Rico Landman, Sebastiaan Haffert, Louis Desdoigts et al. (+7 more)
We report on the goals, design, and ongoing development of the Netherlands
EXoplanet Testbed (NEXT), a high-contrast imaging testbed under construction in Leiden. NEXT is designed to develop and validate technologies and
algorithms for extreme adaptive optics (XAO) and coronagraphy at the performance levels required by the next generation of high-contrast imagers on the Extremely Large
Telescopes (ELTs) and future space observatories. All powered optics in the common path are custom off-axis parabolas, making the bench fully reflective up to the science cameras, and it operates from the visible to the near-infrared (500-1800 nm). It combines a woofer-tweeter XAO module, using an ALPAO woofer and a Boston Micromachines kilo-DM as tweeter, with a coronagraphic arm that supports common coronagraph architectures and focal-plane wavefront control for dark-hole digging, and reserves space for a suite of wavefront sensors. The design targets a raw contrast of $10^{-7}$ (goal: $10^{-8}$) at $5\lambda/D$ and 800 nm. We present the opto-mechanical design of the testbed, the key trade-offs made to reach these contrast levels, and Fresnel-propagation simulations of its predicted performance.
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All authors Rico Landman, Sebastiaan Haffert, Louis Desdoigts, Matthijs Mars, Dhwanil Patel, Daniel Smith, Remko Stuik, Adam Taras, Elena Tonucci, Yinzi Xin
Instrumentation and Methods for Astrophysics
No need to modulate: On-sky results of a Neural Network enhanced pyramid wavefront sensor and prospects for the ELTs
Rico Landman, Liam Koning, Sebastiaan Y. Haffert et al. (+20 more)
One of the main limitations of ground-based extreme adaptive optics systems (XAO) is the balance between the temporal and
photon noise error. The unmodulated Pyramid Wavefront Sensor (uPWFS) promises significant gains in sensitivity over its modulated counterpart, but its practical use is limited by its linearity range. Nonlinear reconstructors provide a pathway to recover this dynamic range while preserving the sensitivity of the uPWFS, thereby reducing
photon noise and improving contrast. We present the real-time implementation of a Convolutional Neural Network (CNN) reconstructor and show on-sky results with MagAO-X, demonstrating robust and stable correction across diverse atmospheric conditions. Significant gains over default operation are seen in the low and moderate Strehl regimes, while the performance is slightly degraded in the high Strehl regime. We diagnose this in simulation and mainly attribute this to a non-optimized training
dataset for the high-Strehl regime, rather than a fundamental limitation of the approach. Furthermore, initial simulations of the NN-enhanced uPWFS for a downscaled version of the Extremely Large
Telescope (ELT) show substantial gains for fast petal-piston control. These results demonstrate that NN-enhanced wavefront sensing is a viable technology for future high-contrast instruments.
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All authors Rico Landman, Liam Koning, Sebastiaan Y. Haffert, Joseph D. Long, Jared R. Males, Matthijs Mars, Laird M. Close, Olivier Guyon, Warren B. Foster, Kyle Van Gorkom, Alexander D. Hedglen, Parker T. Johnson, Maggie Y. Kautz, Jay K. Kueny, Jialin Li, Joshua Liberman, Miles Lucas, Jennifer Lumbres, Eden A. McEwen, Avalon McLeod, Lauren Schatz, Elena Tonucci, Katie Twitchell
Mathematical Physics · Cross-listed from math.OA
A genus zero functorial CFT associated to the vacuum sector of a conformal net
André G. Henriques and James E. Tener
Starting from an arbitrary conformal net, we construct a genus zero functorial conformal field theory whose
Hilbert space is the
vacuum sector of the net. Specifically, we construct an
algebra for the operad of little discs and conformal
embeddings with values in the category of
Hilbert spaces and bounded linear maps. We work with closed discs, and our conformal
embeddings explicitly allow the image of an incoming disc to overlap with the boundary of the outgoing disc. As an application, we show that all conformal nets satisfy the trace class condition: if $L_0$ is the conformal
Hamiltonian of the net, then the operators $r^{L_0}$ are trace class whenever $0 \le r < 1$. In particular, the $L_0$-eigenspaces of a conformal net are automatically finite-dimensional.
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Fluid Dynamics
Feedback control of vortex shedding using data-driven modelling
Jack Proudfoot, Chris J. Nicholls, Brian M. T. Tang et al. (+1 more)
This paper details the data-driven modelling and feedback control of
vortex shedding past a circular cylinder at a Reynolds number of Re = 1000. We study the effect of varying the order of the reduced model for control design purposes and demonstrate that higher orders can lead to lower suppression of
vortex shedding. We use the Bode integral
theorem and a frequency-domain interpretation to show that this drop in performance is, in part, due to the classical “waterbed effect”, which increases sensitivity in frequency bands of unmodelled dynamics. Training data from 2D unsteady simulation is used to obtain linear reduced-order state-space models of the system via dynamic mode decomposition with control. Using only lift measurement, we show that at least a 4th-order model is required for an LQG controller to suppress
vortex shedding, with the best performance achieved with as few as 9 modes, whilst higher-order (>14) controllers show a significant decrease in performance. We study the influence of external disturbances, noise rejection, and parameter uncertainty on controller performance. A 28.6 dB reduction in lift coefficient variance is achieved, resulting in a 26% reduction in drag. We further show that, for control design purposes with practical actuation bandwidth, the closed-loop control delivers a significant 13.7% drag reduction within 3D DDES, despite having been trained with 2D URANS and therefore argue that 2D URANS simulation is sufficient for reduced-order model generation and control design.
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All authors Jack Proudfoot, Chris J. Nicholls, Brian M. T. Tang, Marko Bacic
Quantum Physics
Nearly Optimal Amplitude Estimation at any Depth
Jona Erle and Bálint Koczor
We develop a class of amplitude estimation
algorithms with tunable
circuit depth $M$ and
circuit repetitions $N$, requiring neither ancilla
qubits nor controlled Grover operations. For additive error $\epsilon$ in the Grover angle, they attain the nearly optimal query-depth tradeoff $M^2N\in\widetilde{O}(\epsilon^{-2})$ uniformly over $\lambda\in[0,\pi/2]$, spanning the full range from classical sampling at $M=1$ to the Heisenberg limit at $M=\Theta(\epsilon^{-1})$. While prior depth-tunable work establishes comparable angle-accuracy guarantees only away from the boundaries $\lambda\to0$ or $\pi/2$ or at discrete depth tradeoffs, our guarantee extends to both boundaries, so the
quantum speedup persists there rather than degrading to classical sampling. Numerical experiments confirm the predicted uniform angle accuracy and show low overhead in practice, making them strong candidates for practical amplitude estimation in the early fault-tolerant regime, with applications such as overlap certification, trial-state verification, and Monte Carlo methods.
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Cosmology and Nongalactic Astrophysics
Gaussian process reconstruction of scalar field dynamics from recent cosmological data
Afaq Maqsood, Sonej Alam and Md. Wali Hossain
We reconstruct the late-time expansion history and dark energy dynamics using available cosmological data. We consider dark energy as an effective minimally coupled canonical scalar field without assuming a specific form for its potential. For reconstruction, we use Gaussian Process (GP) regression with a joint
dataset consisting of 32
cosmic chronometer measurements (CC32), DESI DR2
baryon acoustic oscillation data, three Type Ia
supernova compilations (Pantheon+, Union3, and DES Y5), and compressed CMB distance priors. From the reconstructed Hubble parameter and its derivatives, we obtain the scalar field kinetic and potential energy densities, the equation of state $w(z)$, and the dimensionless slope parameter $|\lambda(z)|$ of the scalar field potential. The reconstructed potential is nearly constant at late times, with $\tilde{V}(0) \simeq 0.68$–$0.70\rho_{c,0}$, close to the dark-energy density in flat $\Lambda$CDM. The kinetic term remains small over $0 \lesssim z \lesssim 2.5$, while $w(z)$ remains close to $-1$ within the uncertainties. Using only CC32 and DESI DR2, we find a mild ($1\sigma$) hint of a phantom-divide crossing near $z\sim0.5$. However, this feature depends on the
supernova compilation and cannot be regarded as a firm conclusion with current data. The slope parameter $|\lambda(z)|$ shows mild
evolution, with present-day central values around $0.8$–$1.0$, but large uncertainties due to its dependence on higher-order derivatives of the expansion history. The
curvature parameter $\Gamma(z)$ requires even higher-order derivatives and is not constrained by current data; therefore, we do not report its reconstruction. Allowing small spatial
curvature, $\Omega_k=0$–$0.02$, changes the results only slightly and remains within the existing uncertainty bands.
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Cosmology and Nongalactic Astrophysics
Dark-to-black super-accretion as a spin-imprinting mechanism for supermassive Kerr black holes
Saeed Fakhry, Nicolas Sanchis-Gual, Jorge Castelo Mourelle et al. (+2 more)
The existence of supermassive black holes with masses $M\gtrsim10^9\,M_{\odot}$ and large dimensionless
spins $\chi\sim0.9-0.99$ at high
redshift remains a challenge to our understanding of the early Universe. In this work, we study the adiabatic co-
evolution of a Kerr black hole seed surrounded by two ultralight scalar dark matter clouds occupying different bound states, and show that this configuration allows the black hole to grow into the supermassive mass range while imprinting a characteristic final
spin. The
evolution proceeds through two stages. During the first stage, a spherical cloud described by the $\ell=0$ mode is completely depleted through a runaway dark-to-black
accretion mechanism on a timescale of hundreds of millions of years for
boson masses $\mu\sim10^{-18}-10^{-17}\,\mathrm{eV}$. Since the accreted material does not carry angular momentum, the black hole
spin is universally driven to $\chi\simeq0$, independently of its initial
spin. Throughout this stage, the second cloud, described by the $\ell=m=1$ mode, remains in the superradiant regime with negligible
evolution. However, once the first stage is completed, this cloud transitions to the accreting regime, rapidly transferring both mass and angular momentum to the black hole. Starting from $\chi\simeq0$, the black hole
spin increases until the
evolution self-consistently saturates close to the threshold $\chi_{\rm sat}$, defined by the condition $\Omega_H(\chi_{\rm sat})=\mu$, on an e-folding timescale of thousands of years, orders of magnitude shorter than the first stage. This final saturation
spin is largely independent of both the initial black hole
spin and the mass of the secondary cloud, providing a
spin-imprinting mechanism in which the
primordial spin is first erased by spherical
accretion and then reset to a value determined only by the
boson mass and the final black hole mass.
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All authors Saeed Fakhry, Nicolas Sanchis-Gual, Jorge Castelo Mourelle, Darío Núñez, Juan Carlos Degollado
High Energy Physics (Theory)
Real-time thermal photon-photon interactions in the mixed space
M. A. A. Ahmed, H. Zainuddin, N. M. Shah et al. (+1 more)
Using the effective Lagrangian for the low-energy/temperature of
photon-
photon interaction and the lowest-order
photon self-energy is calculated in the Real Time Formalism (RTF) for an arbitrary path specified by the $\sigma$-parameter within the new basis. The causal Green's functions (without chemical potential) for the scalar field are evaluated to derive the usual thermal propagators in the mixed space. It is shown that the symmetric propagator does not depend on $\sigma-$ parameter. Furthermore, the
photon self-energy is used to calculate some electromagnetic properties, such as dielectric tensor and velocity of light from
photon self-energy in the mixed space that greatly simplifies calculations in RTF. Their time dependence is investigated, and a comparison between our results and those obtained by other models is discussed.
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All authors M. A. A. Ahmed, H. Zainuddin, N. M. Shah, M. Ladrem