Quantum Physics
Enhanced Magnon Synchronization in Coupled WGM Optomagnonic Resonators with Phase-Dependent Photon Hopping
Le-Ji Xue, Ying-Jian Zhu, Jaspal Singh et al. (+4 more)
We investigate
quantum synchronization in a coupled cavity optomagnonic system which consists of two spatially separated optical whispering-gallery-mode (WGM) resonators and each resonator is also coupled to a yttrium iron garnet (YIG) sphere through the optomagnonic interaction. Phase-dependent single-
photon hopping factor couples the two optical resonators and provides an indirect interaction between the two distant
magnon modes. We then investigate complete synchronization, {\phi}-synchronization, and
quantum phase synchronization using the covariance-
matrix formalism as well as also studying the effects of the hopping term on the overall synchronization dynamics of two distant
magnon modes. It can be seen that the
photon-hopping phase provides an efficient way to control the synchronization dynamics and when it is varied from 0 to {\pi}, the
magnon trajectories gradually evolve from weakly correlated motion to a highly synchronized state, which is also accompanied by a significant reduction in the synchronization error. The influence of the
photon-hopping strength and thermal fluctuations is also investigated, where it can be seen that stronger
photon hopping enhances all synchronization measures, while thermal noise weakens the coherent correlations responsible for synchronized dynamics. Our results demonstrate that the phase of the hopping factor offers a simple and effective approach for controlling synchronization dynamics in WGM based coupled cavity optomagnonic systems and also provide a useful route towards coherent control of collective
magnon dynamics in such
quantum optomganonic devices.
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All authors Le-Ji Xue, Ying-Jian Zhu, Jaspal Singh, Ahmad Zahia, Kong-Ming Hu, Jia-Xin Peng, S. K. Singh
Mesoscale and Nanoscale Physics
Anomalous Duffing mechanics of a suspended carbon nanotube quantum dot at ultrastrong coupling
Akong N. Loh, Furkan R. Özyiğit, Fabian Stadler et al. (+3 more)
At cryogenic temperatures, suspended single-wall carbon nanotube
quantum dots act both as prototypical
quantum dots as well as high-quality factor mechanical resonators. Single-electron tunneling enables reaching an ultrastrong electron-vibron coupling regime, where the coupling parameter exceeds the vibration frequency. Due to the high quality factors, a strongly nonlinear Duffing response is easily reached. Here, we quantitatively study the Duffing response parameters of such a device and their relation to Coulomb blockade oscillation. At the edges of single-electron tunneling regions, a local increase of the Duffing parameter corresponding to a stiffening spring is observed. Size and approximate scaling of the effect agree with single-electron tunneling phenomena, which however should lead to softening spring behaviour. Possible causes of these puzzling results are discussed.
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All authors Akong N. Loh, Furkan R. Özyiğit, Fabian Stadler, Katrin Burkert, Niklas Hüttner, Andreas K. Hüttel
High Energy Physics (Phenomenology)
Dynamical criterion for biased domain-wall formation
Wen-Yuan Ai
In the presence of a bias term, the conventional condition for forming a domain-wall network is $p_{\rm fv}>p_c\simeq 0.31$, with $p_{\rm fv}/(1-p_{\rm fv})=\exp(-\Delta V(0)/V_b(0))$, where $p_{\rm fv}$ is the false-
vacuum fraction immediately after the phase transition, $\Delta V(0)$ is the zero-temperature energy splitting between the false and true
vacua and $V_b(0)$ is the zero-temperature barrier height measured from the true
vacuum. This criterion, however, cannot be generally valid, since it is insensitive to the dynamics of the phase transition. In this work, we derive a dynamical criterion for domain wall formation in the presence of a bias term. We evaluate $p_{\rm fv}$ at the freeze-out temperature of the false-
vacuum correlation volumes $T_{\rm fo}$, obtaining a substantially stricter criterion. The same dynamical picture also yields a necessary consistency condition for applying scaling-regime gravitational-wave estimates, $T_{\rm fo}>T_{\rm ann}$, where $T_{\rm ann}$ is the annihilation temperature inferred from the scaling-regime dynamics.
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General Relativity and Quantum Cosmology
Black holes with regular scalar hair in Brans-Dicke gravity via the Herglotz variational principle
Marek Wazny
Brans-Dicke theory is reformulated within the Herglotz variational principle (HVP), and an exact black hole solution with scalar hair is obtained for $\omega_{0}=0$ and vanishing potential $V(\phi)=0$. The scalar profile is strictly positive and the resulting stealth Schwarzschild solution arises without fixing the otherwise arbitrary Herglotz function $\eta(r)$. Motivated by the weak-field limit, the explicit choice $\eta(r)=\eta_{0}(r-2M)^k/r^{k+2}$, with $\eta_0$ a constant of dimension length, produces a scalar field configuration remaining regular at the black hole horizon. Consequently, the HVP provides a new mechanism for evading standard no-hair
theorems in scalar-tensor theories.
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Astrophysics of Galaxies
Projection Is All You Need: Interpreting Polarization Measurements in the Orion Clouds with Sub-Alfvénic MHD Simulations
Feiyu Quan, Yitao Xu, Keping Qiu et al. (+2 more)
Dust polarization observations are widely used to diagnose the relative importance of
magnetic fields and
turbulence in
star forming molecular clouds, often through summary statistics such as the mean polarization direction $\mu$ and dispersion $\sigma$. Recent multi-scale polarization observations of the Orion Integral-Shaped Filament (ISF) reveal substantial diversity in polarization morphology among its dense cores, raising questions about the underlying Alfvénic nature of the cloud. In this work, we develop a statistical framework to compare polarization-based summary statistics from observations with those derived from projected three dimensional MHD simulations, explicitly accounting for projection effects. Using globally sub-Alfvénic simulations that naturally produce slightly super-Alfvénic dense cores, we show that modest deviations of core-scale
magnetic fields from the parent cloud field, when combined with projection, can generate a wide range of plane-of-sky polarization dispersions. Applying hypothesis testing, we find that the observed $(\mu, \sigma)$ values in the Orion ISF are statistically consistent with sub-Alfvénic cloud models over a broad range of viewing angles. This broad degeneracy implies that $\mu$ and $\sigma$ alone cannot provide precise information about the three-dimensional
magnetic-field distribution, and hence the Alfvén Mach number, of an individual cloud. While the observations can provide evidence against certain projection geometries, we demonstrate that polarization statistics based solely on $(\mu, \sigma)$ are insufficient to provide evidence against sub-Alfvénic cloud models. Our results highlight the necessity of explicitly incorporating projection effects when interpreting polarization observations of molecular clouds.
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All authors Feiyu Quan, Yitao Xu, Keping Qiu, Xiaodan Fan, Hua-bai Li
Astrophysics of Galaxies
Lighting Up the CGM: Strong, Jet-Aligned $H\alpha$ Emission around Radio Galaxies
Namrata Roy, Sanchayeeta Borthakur, Timothy Heckman et al. (+1 more)
A primary question within
galaxy evolution is how active
galactic nuclei (AGN) feedback modifies the circumgalactic medium (CGM). We present a search for faint H$\alpha$ emission from the cool ionized CGM ($T\sim 10^4$ K) around
radio galaxies by stacking background-
quasar spectra from DESI sightlines. We take into account the projected distance and position angle of each
quasar sightline relative to the
radio jet axis, and test whether jet–CGM coupling is anisotropic. We detect a strong H$\alpha$ excess at $>5\sigma$ along the collimated
radio jet axis ($\theta<20^\circ$) with a mean integrated flux of $1.19\times10^{-17}\ {\rm erg\ cm^{-2}\ s^{-1}}$. In contrast, the azimuthally averaged stack over all 324 sightline angles yields no detection ($<2\sigma$), indicating that this excess emission is very localized along the
radio jet. We also find that the jet-aligned H$\alpha$ signal is radially structured, where the strongest emission occurs near the host
galaxy just outside the optical half-light radius, and rising again near the projected
radio-lobe region. The jet-aligned stacks reveal H$\alpha$ signal that is roughly 100 times brighter than normal
halos. In the same sightlines however, Mg II absorption shows no difference in incidence between jet-aligned and off-axis directions, with broadly similar equivalent widths, column densities, and line widths. This striking contrast shows that while Mg II traces the ambient, clumpy cool CGM reservoir, the H$\alpha$ emission directly captures localized, low-covering-fraction clouds whose density, pressure, or ionization level has been dramatically boosted by the propagating jet. These results deliver clear evidence of localized jet-CGM interaction in
radio-jetted AGNs.
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All authors Namrata Roy, Sanchayeeta Borthakur, Timothy Heckman, Tanmay Singh
Cosmology and Nongalactic Astrophysics
Compaction function in stochastic inflation: a FOREST of type I and II primordial black holes
Chiara Animali, Pierre Auclair, Baptiste Blachier et al. (+2 more)
We show how to compute the compaction function within
stochastic inflation, by solving the random field dynamics on
stochastic binary trees. In this framework, the compaction function is directly related to the ratio of the volumes emerging from the sibling and child branches of a given node. This construction also determines whether or not the areal radius of a perturbation increases monotonically with the radial coordinate, thereby distinguishing between type-I and type-II fluctuations. As an application, we investigate
primordial black hole (PBH) formation in a single-field toy model with a constant potential slope, using
stochastic-tree realizations generated with the public code FOREST. In the classical regime, where
quantum diffusion is subdominant, the PBH mass function is narrowly distributed and type-II fluctuations are strongly suppressed relative to type I. By contrast, in the
quantum and near-critical (i.e. close to eternal inflation) regimes, the PBH mass distribution spans several orders of magnitude, the overall PBH abundance is enhanced, and type-II fluctuations outnumber type I. In that case cloud-in-cloud effects are also important, highlighting the need for a better understanding of the
evolution and collapse of type-II fluctuations in order to obtain robust PBH predictions when
stochastic effects are significant.
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All authors Chiara Animali, Pierre Auclair, Baptiste Blachier, Eemeli Tomberg, Vincent Vennin
Astrophysics of Galaxies
Strong Stellar Diffusion from Wave DM Cosmological Simulation and Potential Unified Origin for dSphs, UFGs, and UDGs
A. Pozo, T. Broadhurst, J. Zhang et al. (+6 more)
Our $\psi$DM simulations predict that
stars diffuse throughout dark matter
halos over the Hubble time through a random walk driven by the wave perturbations intrinsic to $\psi$DM. The resulting
stellar distribution locally follows a Gaussian profile (Sersic index $n=0.5$), as expected from the central limit
theorem, expanding as $R_{1/2}(t)\simeq(\hbar/m_\psi)^{0.5}\sqrt{t}$, in good agreement with the core–
halo profiles of typical $\psi$DM
dwarf spheroidal
galaxies. The strength of this
diffusion depends on
halo mass and the corresponding
soliton, naturally producing progressively more diffuse
stellar systems in more massive
halos. The observed continuity from faint
dwarfs and compact
dwarf spheroidals to ultra-diffuse
galaxies can therefore be interpreted as an age sequence, with later-forming
dwarfs experiencing less
diffusion and thus remaining smaller and brighter.
Stellar scattering arises from the random walk of the
soliton, gradually transporting
stars from the dense central core into the outer
halo, creating the extended
stellar envelopes observed around Local Group
dwarfs. Rather than being unique to Ultra-Diffuse
Galaxies (UDGs), this wave-driven
stellar diffusion may provide a unified mechanism explaining
galaxy structure across a vast mass range, from ultra-faint
dwarfs to the most massive UDGs, without requiring distinct formation channels or "failed
galaxy" scenarios. The diffuse
stellar halos and globular cluster distributions recently revealed by Euclid may therefore represent direct observational signatures of the granular dynamics of wave dark matter.
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All authors A. Pozo, T. Broadhurst, J. Zhang, M. Oguri, K. Umetsu, R. Emami, L. Hernquist, P. Mocz, M. Vogelsberger
Quantum Physics
Programmable generation of flying cat-qubits
Cecilia Erneman, Zeidan Zeidan, Göran Johansson et al. (+1 more)
We propose a framework for the direct generation of flying cat-
qubit states from
vacuum using time-dependent two-
photon drives in nonlinear bosonic systems. We study both Kerr-based and two-
photon-dissipation-based generation. By engineering Kerr nonlinearity, two-
photon driving, and dissipation, we demonstrate logical control of a cat
qubit during its generation and emission, while its
quantum information is simultaneously shared between the nonlinear system and the propagating output field. We further analyze the effects of
photon loss and pure dephasing, showing that both the state generation and logical control remain robust under realistic noise conditions. These results provide a route toward programmable bosonic
quantum networks and future propagating error-correctable encodings.
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All authors Cecilia Erneman, Zeidan Zeidan, Göran Johansson, Maryam Khanahmadi
Quantum Physics
Cooperative control of dissipative qubits: steering along the fastest dissipative contraction
Robert Weiß, Sandro Wimberger and David Guéry-Odelin
In the control of dissipative
quantum systems, the slow relaxation modes usually set the ultimate manipulation timescale. We show that this bottleneck can be bypassed when dissipation itself is used as the engine of the transfer. For a
qubit with non-unital, anisotropic Bloch relaxation characterized by the ratio $\kappa=T_1/T_2>1$, coherent control can only rotate the Bloch vector, whereas the bath alone can change its length. The fastest transfer between two thermal states therefore consists in steering the Bloch vector, at every instant, along the direction in which the bath contracts it most rapidly. This direction is obtained in closed form and lies slightly beyond the equatorial plane. With strong pulses, the resulting minimum transfer time is a fraction of $T_2$, instead of several $T_1$ for passive relaxation. With bounded fields, the Pontryagin maximum principle yields a bang–singular–bang synthesis whose singular arc is precisely this fastest-contraction direction, and the minimum time exceeds its strong-pulse limit by a correction inversely proportional to the field amplitude. We also determine the full time–energy Pareto front: moderate accelerations require little energy, and the time optimum lies at its steep, high-energy end. Off-axis targets are treated within the same framework; their only additional benefit is a shorter final rotation. These results apply directly to
magnetic-resonance
spins, nitrogen-vacancy centers and superconducting
qubits, all of which operate deep in the strong-pulse regime.
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Materials Science
A parsimonious structure model for the icosahedral quasicrystal Cd5.7Yb
Michael Feuerbacher
A compact structure model for the icosahedral phase Cd5.7Yb is presented. The model is based on a higher-dimensional description and a cut-and-projection procedure to generate the atom distribution in three-dimensional physical space. It strictly employs only spherical or elliptical occupation domains, ensuring a low number of parameters and low calculation cost. In the presented form the model has seven adjustable parameters. Despite its minimalistic setting, the model reproduces available experimental data, such as chemical composition, mass density and electron density distribution, as well as the cluster structure in physical space very well. Nevertheless, the approximation of the occupation domains by spheres and ellipses evidently implies limitations in accuracy and universality. The model can be adapted for the description of other Tsai-type icosahedral phases.
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Materials Science
Phonon-driven Floquet engineering for electronic states
Yu-Chan Tai, Chih-Wei Luo, Noriaki Takagi et al. (+3 more)
Controlling material excitations offers access to novel fundamental and technological properties. The paradigm of Floquet engineering, the manipulation of the electronic structure using a coherent and time-periodic driving source, has attracted significant
attention. While most realizations rely on strong optical fields, coherent
phonons provide an alternative route to realizing Floquet-Bloch states and are expected to enable substantially longer-lived Floquet-Bloch states. We show that
laser-excited coherent
phonons drive Floquet-Bloch states. Using time-resolved multiphoton photoemission combined with
quantum beat spectroscopy on
graphene-covered Ir(111), we track the coherent electronic dynamics of the image-potential states dressed by coherent
phonons. The beat signal indicates the presence of sideband structure with the coherent-
phonon frequency as its fundamental period, consistent with Floquet theory. Furthermore, an independent oscillation in intensity at the same frequency was observed, confirming excitation of the coherent
phonon mode. Compared with conventional light-driven Floquet-Bloch states, the observed
phonon-driven Floquet-Bloch states persist for one to two orders of magnitude longer. These results establish coherent
phonons as a material-driven route to Floquet engineering and demonstrate the long-lived dressing of electronic states beyond the optical excitation window.
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All authors Yu-Chan Tai, Chih-Wei Luo, Noriaki Takagi, Hiroshi Ishida, Chun-Liang Lin, Ryuichi Arafune
Fluid Dynamics
Efficient Wall-Modeled High-Order Compact Gas-Kinetic Scheme for Compressible Turbulent Flows
Yaqing Yang, Fengxiang Zhao and Kun Xu
Scale-resolving simulations of wall-bounded turbulent flows remain prohibitively expensive at high Reynolds numbers, owing to the stringent near-wall resolution requirements. High-order compact gas-kinetic schemes (CGKS) are accurate, robust, and efficient for compressible flows, making them an attractive foundation for reducing this cost. Building on the fifth-order scheme CGKS-5th, we develop a wall-modeled CGKS framework that alleviates the near-wall resolution burden through a pressure-gradient-based non-
equilibrium wall model while preserving the resolving power of the outer solver. CGKS-5th resolves the outer flow and supplies the wall model with data at the exchange location. On coarse near-wall meshes, the wall model reconstructs the under-resolved viscous wall stress, while CGKS-5th provides the inviscid wall flux directly; the two combine to form the wall momentum flux. To capture non-
equilibrium effects in adverse-pressure-gradient and separated regions, the wall model retains a pressure-gradient source term together with a pressure-gradient-corrected near-wall damping function. We assess the framework on two distinct flows: bluff-body separation past a circular cylinder, and a shock-induced separation bubble on the transonic RAE 2822 airfoil, using near-wall meshes far coarser than wall-resolved simulations require. For the RAE 2822 case, this corresponds to a twentyfold coarsening in the wallnormal direction, with comparable coarsening in other directions. In both cases, the wall-modeled CGKS-5th reproduces the separated flow structures and markedly improves near-wall predictions over its wall-model-free counterpart, most notably the skin-friction coefficient. The framework thus delivers accurate predictions of these separated flows at substantially reduced near-wall cost, while its lightweight coupling adds less than 1% runtime overhead in a multi-GPU implementation.
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Mesoscale and Nanoscale Physics
Perfect elliptic dichroism: Probing the metric of anisotropic quantum Hall droplets
Bruno Mera, Alberto Nardin, Anaïs Defossez et al. (+3 more)
Understanding the geometry of
quantum Hall systems is a central challenge in modern condensed matter physics. We introduce a framework for probing the
geometric structure of
quantum Hall droplets by engineering the geometry of a dichroic probe and identifying the onset of "perfect
elliptic dichroism", a regime in which the system responds exclusively to an elliptically polarized drive of a given chirality. This phenomenon provides a direct diagnostic of the droplet's intrinsic metric, and we show that it extends naturally to ideal Chern bands, where holomorphicity of the occupied states guarantees the vanishing of one
chiral absorption rate with a quantized response for the other. In
lattice realizations, such as the Harper-Hofstadter model, finite
lattice-spacing corrections break the exact continuum metric description and give rise to a renormalized, emergent Landau-orbit metric; the probe ellipticity at which perfect dichroism is achieved then shifts accordingly, offering a direct spectroscopic window onto this
lattice-induced
geometric renormalization. Our results illuminate the rich
geometric structure of
quantum Hall phases and offer concrete pathways for observing these effects in
quantum-engineered platforms.
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All authors Bruno Mera, Alberto Nardin, Anaïs Defossez, Baptiste Bermond, Tomoki Ozawa, Nathan Goldman
Mesoscale and Nanoscale Physics
Hall viscosity from metric-sensitive dichroic probes
Alberto Nardin, Bruno Mera, Anaïs Defossez et al. (+3 more)
Hall viscosity characterizes the
geometric response of a
quantum Hall droplet to deformations of the underlying metric, yet it has remained difficult to measure directly. We propose a spectroscopic probe based on circular dichroism, using
chiral metric-sensitive drives – implemented as rotating quadrupolar ("saddle") perturbations – that effectively modulate the metric and couple to the generators of area-preserving deformations. The resulting dichroic signal directly measures the
Hall viscosity, while frequency-resolved spectroscopy disentangles it from other excitations. A local formulation further enables spatially resolved markers of
Hall viscosity applicable to both continuum and
lattice systems. Our results open a direct route to measuring
Hall viscosity in
quantum-engineered platforms such as cold atoms in optical
lattices.
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All authors Alberto Nardin, Bruno Mera, Anaïs Defossez, Baptiste Bermond, Tomoki Ozawa, Nathan Goldman
High Energy Physics (Theory)
Nonlinear nature of near-equilibrium viscous fluids
Yan Liu and Hao-Tian Sun
We study the late-time relaxation of a neutral relativistic viscous fluid in $d+1$ dimensions. In the long-wavelength regime, linearized hydrodynamics predicts that the sound mode at momentum $nk$ decays as $e^{-n^2\omega_I t}$. However, nonlinear analysis gives a decay of $e^{-n\omega_I t}$. We derive a closed asymptotic attractor solution in which the frequency of the $n$-th harmonic locks to $n$ times the complex frequency of the fundamental mode. The amplitude envelopes for energy current $J$ obey a simple cascading relation, $J_n=\alpha_J^{\,n-1}J_1^n$, with $\alpha_J$ fixed by the equation of state, the longitudinal viscosity, and the fundamental wavenumber. For conformal fluids, $\alpha_J=1/(8\eta k)$, in agreement with the
holographic result of arXiv:2512.07242. The existence of the attractor shows that, even near
equilibrium, field powers are not equivalent to amplitude order.
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Soft Condensed Matter
A phase-field model for viscoelastic compressible tumor growth
Luise Zieger, Min Wu, Chaozhen Wei et al. (+2 more)
It is well known that growing tumors generate and respond to stress in their local microenvironment. Tissue re-arrangements can relax these mechanical stresses and make the tissue more fluid-like. Further, intricate coupling between mechanotransduction and biochemical signaling leads to complex patterns of growth. To predict the outcomes of these nonlinear interactions, we develop a phase-field model to simulate tumors growing into a surrounding medium taking into account their elastic and viscous properties as well as their compressibilities. We couple continuum modeling of the viscoelastic mechanics to the concentration of a diffusible growth-promoting nutrient in a mass conservative way. The phase-field method is a stable and flexible way to describe the dynamics of arbitrarily shaped tumors. We demonstrate convergence of the phase-field model to a sharp interface model in radially symmetric geometries and can observe progression to stationary tumors. However, our results show that these stationary symmetric tumors are subject to
symmetry-breaking instabilities in 2D and 3D driven by two primary mechanisms: (i) elastic buckling instabiliies due to differential growth induced by the nutrient gradient and (ii) instabilities generated by apoptosis-related volumetric loss. Further, tissue fluidity and compressibility can lead to changes in tumor
topologies. Our modeling framework provides a robust methodology for investigating how tissue mechanics and growth factor signaling influence the progression and invasive potential of solid tumors.
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All authors Luise Zieger, Min Wu, Chaozhen Wei, John Lowengrub, Sebastian Aland
Quantum Physics
Coherent Control of Quantum and Classical Correlations in Photoionization
Axel Stenquist and Jan Marcus Dahlström
The ability to control
quantum correlations in strongly driven systems is a central challenge across
quantum science, with implications for ultrafast dynamics,
quantum control, and information processing. In photoionization, the emitted electron and residual ion may form an entangled system whose correlations encode the underlying light-matter interaction, yet control of their generation and observable manifestation in continuum systems remains largely unexplored. Here we demonstrate phase-resolved control of electron-ion correlations using phase-locked pulse sequences in the strong-coupling regime. We show that
entanglement can be halted and reshaped with attosecond precision, and that phase-dependent correlations can be redistributed into population-based correlations, leading to
entanglement that is directly reflected in joint observables. These results establish a route to coherently shape
entanglement in photoionization and open new possibilities for accessing and controlling
quantum correlations in systems where measurements are intrinsically basis constrained.
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General Relativity and Quantum Cosmology
Physical nonviability of $f(\mathbb{Q})$ in the scalar-tensor representation
Jose Beltrán Jiménez, Alejandro Jiménez Cano and Tomi S. Koivisto
We show the known pathological character of $f(\mathbb{Q})$
gravity in its scalar-tensor representation.
High Energy Physics (Theory) · Cross-listed from math.QA
Deformed W-algebras and chiralized cluster seeds: subregular W-algebras and Inverse Quantum Hamiltonian Reduction
Mikhail Bershtein, Jean-Emile Bourgine and Ethan Fursman
The recently introduced formalism of
chiral cluster seeds replaces
quantum cluster variables with deformed vertex operators. In this framework, a decorated quiver associated with a seed encodes the operator product expansions of the corresponding vertex operators. This formalism is applied to several $(q,t)$-deformed W-
algebras, including $\mathcal{W}_{\mathfrak{q},\mathfrak{t}}(\mathfrak{gl}(N|M))$, $U_q(\widehat{\mathfrak{sl}}_2)$, and the deformed Bershadsky–Polyakov
algebra. In particular, it is shown that different free field realizations of the currents are related by mutations of the associated
chiral cluster seed. The second part of the paper introduces a $(q,t)$-deformation of the subregular W-
algebras, denoted by $\mathcal{W}_{\mathfrak{q},\mathfrak{t}}^{\text{sub}}(\mathfrak{sl}(N))$. All free field realizations obtainable through seed mutations are described. An
embedding of $\mathcal{W}_{\mathfrak{q},\mathfrak{t}}^{\text{sub}}(\mathfrak{sl}(N))$ into the free field realization of $\mathcal{W}_{\mathfrak{q},\mathfrak{t}}(\mathfrak{sl}(N))$ tensored with a rank-two Heisenberg
algebra is constructed. This
embedding may be viewed as a deformed analogue of inverse
quantum Hamiltonian reduction. The relation between the subregular
algebras and $\mathcal{W}_{\mathfrak{q},\mathfrak{t}}(\mathfrak{gl}(1|N))$ is also discussed.
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Instrumentation and Methods for Astrophysics
ESOFinder: an LLM-powered tool to help users navigate ESO documentation
P. Sánchez-Sáez, C. Reinero, M. Vioque et al. (+6 more)
The large amount and diversity of documentation available for users of the European Southern Observatory (ESO), spanning the full observing lifecycle from proposal preparation and observation planning to data reduction and archival access, makes it increasingly challenging for the astronomical community to efficiently find relevant information. To address this, we have developed ESOFinder, an in-house chatbot powered by Large
Language Models (LLMs) and
Retrieval Augmented Generation (RAG). ESOFinder integrates public information from instrument manuals, phase 1/2/3 documentation, data reduction pipeline manuals, the ESO Knowledge Base, and key web resources (spanning more than 3500 links and over 100 manuals) to provide concise, context-aware, and reference-linked answers to user queries about proposal or observation preparation, data
retrieval, and data processing. Built on open-source LLMs, running on a local server, ESOFinder ensures data
privacy, transparency, and complete control over the knowledge base. Its multi-step architecture allows verification of retrieved documents and generated answers, reducing the risk of
hallucinations and improving the reliability of responses compared to commercial tools. The current version of ESOFinder is being tested internally at ESO to evaluate its performance, assess its integration with internal workflows, and identify limitations in coverage and accuracy. These tests will guide further improvements, including the incorporation of additional documentation, and enhanced
retrieval strategies. Ultimately, ESOFinder aims to become an interface for users to navigate ESO's complex documentation ecosystem and to support both staff and community astronomers in their daily tasks.
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All authors P. Sánchez-Sáez, C. Reinero, M. Vioque, M. Wittkowski, M. Rejkuba, M. Romaniello, A. Barnes, J. Pritchard, M. Marsset
Instrumentation and Detectors
Improving Muon-Scattering Material Identification via Coarse Momentum Encoding and Unsupervised Domain Adaptation
Yuxin Bao, Zhao Zhang, Pei Yu et al. (+7 more)
Cosmic-ray
muon scattering has shown considerable potential for detecting
nuclear materials and other dense contraband, but practical deployment remains challenging. A major difficulty arises from the coupling between material properties and
muon momentum, since the broad natural momentum distribution influences the scattering angle and prevents unambiguous material identification. In this work, we propose a Coarse Momentum-Aware Domain Adaptation (CMADA) method to enable precise identification of materials. Instead of relying on high-precision momentum measurements, the proposed framework adopts coarse momentum binning combined with unsupervised domain adaptation to learn transferable scattering representations. In addition, a precision review mode based on averaging repeated samplings was proposed to further enhances identification performance. The coarse momentum binning strategy improves same-domain identification accuracy from 62.15% without momentum information to 89.52% with 5-bin momentum information, and further to 93.37% (precision review mode). Furthermore, the proposed unsupervised domain adaptation framework improves the cross-domain identification accuracy from 71.71% for the source-only baseline to 89.00% without requiring target domain labels.
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All authors Yuxin Bao, Zhao Zhang, Pei Yu, Liangwen Chen, Weibo He, Yu Zhang, Yuhong Yu, Xueheng Zhang, Lei Yang, Zhiyu Sun
Astrophysics of Galaxies
Probing Magnetic Fields In and Around Galaxies Near and Far
S. A. Mao, Rainer Beck, Aritra Basu et al. (+14 more)
In order to understand the magnetization of
galaxies and the role of
magnetic fields in feedback processes that govern
star formation and
galaxy evolution, it is essential to have a comprehensive census of
magnetic fields in and around
galaxies from the nearby Universe to high
redshifts. In this chapter, we outline the science goals, strategies, techniques, and observational requirements with SKA AA4 for (1) a homogeneous polarimetric survey of nearby
galaxies - mapping both the diffuse polarized emission as well as producing a dense RM grid within the virial radius; (2) a survey of the interstellar
magnetic fields in distant
galaxies targeting strong
lensing systems with polarized lensed
quasars, as well as a general statistical back-illumination survey to probe the
redshift evolution of
magnetic fields in the CGM. These proposed observations will serve as a major step towards understanding the co-
evolution of
galaxies and their
magnetic fields over
cosmic time and provide constraints on
galactic dynamo theories.
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All authors S. A. Mao, Rainer Beck, Aritra Basu, Lerato Baidoo, Andrea Bracco, Ralf-Jürgen Dettmar, Volker Heesen, Cathy Horellou, Timea O. Kovacs, Kohei Kurahara, Yu-Qing Lou, Yik Ki Ma, Rikuto Omae, Rosita Paladino, Amit Seta, Fatemeh Tabatabaei, Theresa Wiegert
Quantum Physics
Deterministic nonlinear bunching of bosons
Kingshuk Adhikary, Darren W. Moore and Radim Filip
The ability of bosonic energy quanta to bunch together in an energy-conserving interaction is a fundamental feature of
quantum harmonic oscillators. Linear systems together with measurement allow for the conditional concentration of energy quanta and, subsequently, breeding of the
quantum states, but only with an exponentially decreasing success rate. Deterministic, energy-conserving and unconditional bunching however, requires nonlinearity. We investigate which nonlinear energy-conserving interactions deterministically combine
bosons into high number states at the same frequency. We show that in order to do so it is advantageous to use nonlinear interactions involving highly saturable systems, such as
qubits, as they preserve the hierarchical
quantum non-Gaussian features and are also sufficiently robust against pure loss. Nonlinear bunching therefore demonstrates the advantage of a
qubit-inside nonlinearity and opens new directions in the deterministic preparation, processing, and detection of
quantum non-Gaussian states.
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Earth and Planetary Astrophysics
ASTEP confirmation of a pair of long-period Jupiter-sized planets with extremely low densities transiting TOI-791
Georgina Dransfield, Antoine C. Petit, Amaury H.M.J. Triaud et al. (+45 more)
Gas
giant planets with periods $20~<~P~<~300~\rm days$ orbiting Sun-like
stars are a relatively uncommon outcome of planetary formation, and key questions about the nature and formation of this sub-population remain unanswered. Theoretical models for the location of their formation (in- or ex-situ) and for their subsequent migration predict different outcomes in terms of
planet masses and eccentricities, indicating that observations have a key role to play in disentangling their histories. In this work we present the discovery and confirmation of a pair of long-period Jupiter-sized
planets transiting an F7
star: TOI-791 b is a $0.993\pm0.033\rm~R_{Jup}$
planet on a $139.29931_{-0.00012}^{+0.00011}~\rm day$ orbit, and TOI-791 c, a $1.155\pm0.040\rm ~R_{Jup}$
planet on a $232.01570_{-0.00071}^{+0.00067}~\rm day$ orbit. The two
planets are within 0.07% of a second-order 5:3 period commensurability leading to transit timing variations (TTVs) of up to 50 minutes. We confirm their planetary nature using ground-based photometry, including multiple full detections of the $>11~\rm hr$ transits of both TOI-791 b and c from Antarctica with ASTEP, making these the longest-duration transits ever observed in their entirety from the ground. Our detailed analysis of the TTV signal allows us to measure dynamical masses for both
planets, which yield densities of $\rho_{\rm b}=0.038\pm0.008 \rm ~g~cm^{-3}$ and $\rho_{\rm c}=0.047\pm0.006 \rm ~g~cm^{-3}$, indicating that TOI-791~b and c are two of the lowest density
giant planets ever detected. While these measurements are robust, further follow-up is needed to fully characterise the TTV signal and the architecture of the system.
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All authors Georgina Dransfield, Antoine C. Petit, Amaury H.M.J. Triaud, Tristan Guillot, François-Xavier Schmider, Lyu Abe, Abdelkrim Agabi, Khalid Barkaoui, Thomas A. Baycroft, Philippe Bendjoya, Rafael Brahm, Karen A. Collins, Billy Edwards, Phil Evans, Alix V. Freckelton, Nolan Grieves, Steve B. Howell, Franco Mallia, Djamel Mekarnia, Angelica Psaridi, Daniel Sebastian, Keivan G. Stassun, Chris Stockdale, Amalie Stokholm, Olga Suarez, Thiam-Guan Tan, Mathilde Timmermans, Cristilyn N. Watkins, Carl Ziegler, Abderahmane Soubkiou, François Bouchy, Marion Cointepas, Vincent Deloupy, Maximilian N. Günther, Michaël Gillon, Giovanni Isopi, Emmanuel Jehin, Jon M. Jenkins, Andrés Jordán, Martin B. Nielsen, Sara Seager, Avi Shporer, Julia V. Seidel, Michal Steiner, Trifon Trifonov, Joseph D. Twicken, Joshua N. Winn, Aldo Zapparata
Applied Physics
Probing Light-Matter Interaction with Topological Data Analysis
Timothy Holt, Maxim Goryachev and Jeremy Bourhill
We explore application of Topological Data Analysis to study light matter interaction through scattering response data in different dimensions. This method is robust against Fano resonance backgrounds in both strong and weak coupling regimes, maintaining accuracy even with reduced mode contrast, distorted lineshape, and the introduction of random trace noise. It scales to any number of interacting modes, reflecting the system's effective degrees of freedom. Crucially, TDA is not merely peak counting but reveals phase-encoded features in the scattering response and may be used even for a fully saturated amplitude response. The analysis is also applied to a three mode system with time reversal
symmetry breaking, revealing change in apparent number of loops and voids in combined two way scattering data. This approach is demonstrated to differentiate the three Dyson ensembles through their topological complexity and probability density functions, enabling analysis of complex modal systems.
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Fluid Dynamics
Exact analytical solutions for the piston effect in supercritical fluids under post-acoustic approximation – Short-time asymptotics, thermal penetration depth and comparison with the Spacelab D-2 experiments
Mátyás Szücs
Near the
liquid-vapor critical point, fluids become highly compressible, giving rise to a special, strongly coupled thermo-mechanical process: the piston effect. In this phenomenon, a thin thermal boundary layer develops near a heated wall; owing to strong thermal expansion, this layer acts like a piston, compressing the bulk fluid adiabatically and resulting in a seemingly accelerated thermal response. Although the piston effect is a thermo-acoustic process, the characteristic time scale of the boundary perturbation is typically orders of magnitude larger than the acoustic time scale of the setup. Consequently, rapid acoustic propagation can be neglected, justifying a post-acoustic approximation with a spatially uniform but time-dependent bulk pressure. Within the linear regime, the temporal
evolution of pressure can be directly connected to the heat flux entering through the boundaries. As a result, the problem reduces to a
diffusion equation governed by a spatially homogeneous source term that depends explicitly on the boundary conditions. Exact, closed-form analytical solutions are derived for effectively one-dimensional problems in both Cartesian and spherical coordinates, considering boundary conditions of the first and second kinds. Short-time asymptotic behavior and thermal penetration depth are analyzed for all four cases. By incorporating the heat capacity of a container via a homogeneous model, an effective boundary condition coupling the wall heat flux and the time derivative of the wall temperature is derived, allowing for a direct comparison with experimental data from the Spacelab D-2 mission. The analytical predictions show good agreement with the experimental results without relying on any numerical simulations.
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Materials Science
Analytical approximations of dispersion laws and ultra-complex conductivity diagrams
A.Ya. Maltsev
We study the probability of the emergence of ultra-complex conductivity diagrams in conductors that satisfy the tight-binding approximation and have the simple or body-centered cubic
lattice. The presence of ultra-complex conductivity diagrams allows us to observe a number of highly nontrivial effects in strong
magnetic fields, however, the probability of their emergence in a given substance is quite low. In the case of the simple or body-centered cubic
lattice, the leading tight-binding approximation does not allow us to estimate this probability due to the peculiarities of the spectra in this situation. To estimate this probability, we use higher-order corrections to the leading approximation, which yield more accurate analytical expressions for the electron spectra.
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Optics
Dynamic Topological Light Control in Reconfigurable Non-Hermitian Metastacks
Ryan Hogan, Zihan Lu, Han Peng et al. (+4 more)
Metasurfaces often require complex lithography for dynamic optical control. To overcome this, we utilize a lithography-free, non-Hermitian planar metastack comprising a distributed Bragg reflector and a vanadium dioxide (VO2) thin film. By virtue of temperature and thermal hysteresis as an active synthetic dimension and exploiting the VO2
insulator-to-metal transition, we actively tune topological interface states to achieve polarization-sensitive spectral control. Notably, our system hosts path-dependent exceptional points (EPs); the intermediate hysteretic states generate a continuum of hot and cold EP pairs that ultimately converge into a single, degenerate EP. Furthermore, we experimentally observe wide-range dynamic optical control, comprising reversible 8% spectral shifts with near-unity reflectance modulation, alongside potential for ultrafast dynamics. Ultimately, our CMOS-compatible design provides a scalable, simple platform for active and topological photonics.
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All authors Ryan Hogan, Zihan Lu, Han Peng, Jie Zhou, Yanling Xiao, Shining Zhu, Hui Liu
Applied Physics
Design and Realization of Broadband Magnonic Spectrometers With Local Electrical Outputs
Johannes Greil, Maximilian Hofschen, Felix Naunheimer et al. (+3 more)
Microscopic
radio-frequency (RF) devices based on propagating
spin waves (SWs) are promising for compact, energy-efficient RF signal processing, but their implementation is impeded by fabrication complexity and the lack of efficient electrical readout. In this work, we demonstrate a SW-based Rowland circle spectrometer with electrical input and local electrical output transducers. The device is realized using a scalable fabrication process based on sputter deposition and wet-chemical etching of Yttrium-Iron-Garnet (YIG), forming concave grating structures with micrometer-scale features. The device functionality is confirmed by combined electrical and magneto-optical measurements, which show that the deflection of SW wavefronts at different input frequencies closely follows the analytically predicted behavior. The linear excitation of SWs via two input tones further confirms the spectrometer operation for simultaneously propagating waves. Beyond the single-device demonstration, we propose a concept for scalable architectures comprising multiple Rowland circles with tunable operating points. When combined with broadband parallel electrical readout, this approach enables control over bandwidth and spectral resolution, which are relevant to spectral occupancy detection in wireless communication systems.
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All authors Johannes Greil, Maximilian Hofschen, Felix Naunheimer, Ádám Papp, György Csaba, Markus Becherer