Superconductivity
Strange Metal Hall Effect in Underdoped BaFe$_2$(As$_{1-x}$P$_x$)$_2$
Augusto Ghiotto, Darian Hall, Yuanqi Lyu et al. (+7 more)
The unusual transport properties of strange metals point to the breakdown of the quasiparticle picture, the understanding of which remains one of the most vexing problems in physics. Here, we report investigations of the electrical
Hall effect of the strange metal
superconductor BaFe$_2$(As$_{1-x}$P$_x$)$_2$. We show that a doping-independent contribution to the
Hall effect exists within a fan shaped region above a putative
quantum critical point. This `strange metal
Hall' contribution echoes many of the properties of the antiferromangetic
Hall response, but attains universal properties that distinguish it from the effects of
Fermi surface reconstruction. This is consistent with an underlying origin connected to the presence of critical fluctuations, tying it to observations of $T$-linear resistivity and the appearance of unconventional superconductivity.
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All authors Augusto Ghiotto, Darian Hall, Yuanqi Lyu, Kohtaro Yamakawa, Sophie Rodehutskors, Corina Dunn, Philip J. W. Moll, John Singleton, Nikola Maksimovic, James G. Analytis
Nuclear Theory
Correspondence between hydrodynamic frames, transport coefficients, and hydrodynamic modes in relativistic fluids
Md Hasanujjaman and Mahfuzur Rahaman
The choice of hydrodynamic frame directly influences the numerical values of transport coefficients in relativistic dissipative hydrodynamics. We derive the exact transformation between the Eckart and Landau–Lifshitz frames and show that their thermal conductivities are related by an enthalpy-dependent factor. Using a
baryon-rich relativistic fluid described by a Boltzmann nucleon gas equation of state, we find that the Landau–Lifshitz thermal conductivity is suppressed relative to the Eckart conductivity, with the difference increasing with temperature and
baryon chemical potential. A linearized analysis of sound propagation demonstrates that the sound attenuation coefficient remains identical in both frames, confirming the frame invariance of physical observables. Our results show that the frame dependence of transport coefficients reflects only the different decomposition of dissipative effects into heat-flow and
diffusion currents, while the underlying transport physics remains unchanged. These findings underscore the importance of specifying the hydrodynamic frame when comparing transport coefficients from heavy-ion collisions,
lattice QCD, and kinetic-theory calculations.
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Applied Physics
Spin-torque microwave detectors of positive rectangular pulse signals
V. Prokopenko, O. Shtanko, I. Sotnyk et al. (+1 more)
We analyze the performance of a
spin-torque microwave detector (STMD) driven by positive rectangular current pulses $I(t)$ of various amplitudes $I_0$, durations $\tau$, and repetition periods $T$ and reveal two distinct regimes of STMD operation. In the first (linear) regime, the time-averaged voltage across the detector, $U_{\rm dc}$, changes linearly with the pulse amplitude $I_0$ and depends on the ratio $\tau/T$: $U_{\rm dc} \sim I_0 (\tau/T)$. This regime is observed for a wide range of pulse amplitudes $I_0$ in the case of in-plane (IP) magnetization dynamics and for rather small pulse amplitudes $I_0 \le I_{\rm th}$ in an STMD with out-of-plane (OOP) magnetization dynamics. The other (nonlinear) regime is characterized by voltage jumps and drops and is observed only in a structure with OOP magnetization dynamics for input pulses with short repetition periods and large amplitudes $I_0 \ge I_{\rm th}$. We believe that the linear regime of STMD operation can be used to unambiguously detect input pulse parameters, which could be important for the development and optimization of spintronic devices capable of detecting and processing non-harmonic (e.g., digital) microwave signals.
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All authors V. Prokopenko, O. Shtanko, I. Sotnyk, O. Prokopenko
Quantum Gases
Imaging the vacuum fluctuations of a quantum field
Yansheng Zhang, Feiyang Wang, Yi Jiang et al. (+5 more)
Heisenberg uncertainties lead to inevitable fluctuations in the measurement outcomes for
quantum-mechanical observables. For
quantum fields, these uncertainties result in random spatial structures in snapshots of a field, even when the field is in its ground (
vacuum) state. Such `
vacuum fluctuations' are at the heart of a wide range of phenomena, from spontaneous decay processes to the Casimir force and Hawking radiation. Their existence is a key manifestation of the quantumness of the physical world, but usually it is only their consequences that are directly observed. Here, we directly observe spatial
vacuum fluctuations of a bosonic
quantum field. Our experiments are based on a homogeneous planar atomic Bose–Einstein condensate. The condensate comprises two coherently coupled interacting components (
spin states), and the
quantum field describes its
spin degrees of freedom. In the regime where the interactions dominate over the coherent coupling, our system emulates a (massive relativistic) sine-Gordon field. Images of the field reveal simultaneous fluctuations on different length scales, with scale-dependent amplitudes consistent with theoretical predictions for a
vacuum state. Observing such fluctuations in the sine-Gordon limit opens many possibilities for laboratory simulations of relativistic fields in regimes that are presently not theoretically tractable.
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All authors Yansheng Zhang, Feiyang Wang, Yi Jiang, Alexander C. Jenkins, Paul H. C. Wong, Christoph Eigen, Gehrig Carlse, Zoran Hadzibabic
Mesoscale and Nanoscale Physics
Signatures of a light-induced exciton condensate exhibiting BEC-BCS crossover
Khanh Duy Nguyen, Gabriele Berruto, Yunhe Bai et al. (+7 more)
Exciton condensates provide a platform to study quasiparticle pairing, Bose-Einstein condensation-Bardeen-Cooper-Schrieffer (BEC-BCS) crossover, and excitonic topological phenomena. Achieving a nonequilibrium
exciton condensate allows the ultimate tunability of these emergent phenomena. Yet, evidence of a light-induced, nonequilibrium
exciton condensate and its BEC-BCS crossover remains elusive. Here, we use time- and angle-resolved photoemission spectroscopy to demonstrate signatures of a non-
equilibrium exciton condensate and its BEC-BCS crossover in monolayer MnBi2Te4. Following optical excitation, a distinctive hole-like dispersion representing
excitons emerges and persists for >20 ps. Strikingly, energy-domain sharpening in the valence band occurs 2 ps after time zero and exhibits a sharp onset at a threshold pump fluence of 0.84 mJ/cm2. The delayed and strongly nonlinear response is difficult to reconcile with transient field effects or conventional carrier-induced band shifts but is consistent with a model of
exciton condensation governed by a Berezinskii-Kosterlitz-Thouless transition. The estimated threshold
exciton density agrees quantitatively with the Nelson-Kosterlitz critical density. At higher fluences, the
exciton feature develops a camel-back-shaped dispersion, consistent with the BEC-BCS crossover in the condensate framework. Our work establishes ultrathin MnBi2Te4 as a model system for studying nonequilibrium
exciton condensates with a connection to superconductivity and
exciton-driven topological phases.
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All authors Khanh Duy Nguyen, Gabriele Berruto, Yunhe Bai, Thomas Marchese, Woojoo Lee, Haoran Lin, Jiangang Yang, Chong Liu, Y. Shirley Meng, Shuolong Yang
Astrophysics of Galaxies
The Nearby Star Formation and Supernova Histories Reconstructed from Young Star Clusters
Cameren Swiggum, Catherine Zucker, Michelangelo Pantaleoni González et al. (+8 more)
We reconstruct the recent
star formation and core-collapse
supernova (ccSN) histories of the
Solar Neighborhood from the past trajectories of young
star clusters. Using a
Gaia-based cluster sample with newly derived ages, masses, and bulk 3D velocities, we integrate orbits backward in an assumed axisymmetric
Galactic potential and combine the trajectories with IMF sampling and
stellar lifetimes to infer ccSN times and locations over the past 50 Myr. The result is an all-sky, 3D, time-resolved map of nearby ccSN activity for comparison with high-resolution 3D views of the local interstellar medium. The 0–15 Myr map shows strong enhancements toward Orion, Vela, Sco–Cen, and Cepheus, many within present-day cavities and shells. At earlier times, the dominant enhancements trace the Collinder 135, Messier 6, and Alpha Persei cluster families, showing how the remnants of massive
star-forming complexes have shaped the recent local feedback history. We recover a bursty
star formation history followed by a delayed, smoother ccSN history. Over the last 40 Myr, the mean
star formation and ccSN rates are \(823~M_\odot~\mathrm{Myr}^{-1}\) and \(7.7~\mathrm{Myr}^{-1}\), respectively, corresponding to a Milky Way rate of \(0.55\pm0.03~\mathrm{century}^{-1}\). Present-day OB-
star catalogs yield rates ranging from agreement with the cluster reconstruction to several times higher. Because the catalogs overlap weakly and require different corrections, we do not rescale the ccSN map. Our reconstruction provides an empirical framework for connecting the recent history of massive-
star feedback to the 3D structure and life cycle of gas in the nearby Milky Way.
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All authors Cameren Swiggum, Catherine Zucker, Michelangelo Pantaleoni González, Emily L. Hunt, Robert A. Benjamin, Sebastian Hutschenreuter, Alena K. Rottensteiner, Efrem Maconi, Lewis McCallum, João Alves, Sebastian Ratzenböck
Optics
Computational Methods of Wave Propagation for Semiclassical Models of High Harmonic Generation in Bulk Solids
Ava N. Hejazi, Nicholas Karpowicz, Gregory D. Scholes et al. (+1 more)
We present a theoretical framework for self consistent treatment of nonlinear light-matter interactions in the ultra-fast strong-field regime based on numerical solution of Maxwell's equations and
semiconductor Bloch equations. This framework is shown to describe high-order harmonic generation and propagation in bulk
semiconductors, investigating differences in reflected and transmitted harmonic spectra due to propagation effects. We show that the propagation of the combined field of the driving
laser pulse and generated harmonics in a bulk
semiconductor significantly modifies the harmonic spectra, affecting interpretation of experimental results relating the transmitted harmonic spectra to the underlying electronic structure of the material. This model allows the self-consistent description of strong-field light-matter interactions in the non-perturbative regime, opening the way to explore the transition between fully classical and
quantum regimes of interaction, tunneling and multiphoton regimes of material ionization, and perturbative and non-perturbative regimes of harmonic generation in bulk materials.
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All authors Ava N. Hejazi, Nicholas Karpowicz, Gregory D. Scholes, Julia M. Mikhailova
Chaotic Dynamics
Coherent states in quantum billiards constructed in the basis of the continued eigenfunctions
I.D. Burkov and S.S. Seidov
In the article a new approach to construction of generalized coherent states in
quantum billiards is proposed. The coherent states are defined as the projections of a Gaussian wave function on the basis of the eigenstates of the
quantum billiard, continued outside. The continuation is built as the solution of the equivalent Balian–Bloch equation, defined on the entire $\mathbb{R}^2$ and the projection operator is built using the resolvent of the Balian–Bloch equation. In the case of the one–dimensional potential well and billiards, belonging to the Coxeter group, the wave functions of the coherent states were expressed analytically via the Jacobi and Riemann theta functions.
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Mathematical Physics · Cross-listed from math.AP
A two-point phase recovering with spherical wave reference
R.G. Novikov and V.N. Sivkin
We consider a reference wave, a radiation solution, and the sum of these solutions (total solution) for the Helmholtz equation in an exterior region. We give two-point formulas for approximate phase recovering of the radiation solution from the intensity of the total solution for the case of spherical reference wave. We show that these formulas can be used, in particular, for approximate phase recovering from
holographic data on a single plane. By these formulas, we continue previous studies with plane wave reference.
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Plasma Physics
Excitation of the lower-hybrid drift instability in the outflow of electron-only magnetic reconnection
B. K. Russell, K. Sakai, Y. Zhang et al. (+17 more)
We report experimental evidence for the lower-hybrid drift instability in the current sheet normal direction of electron-only
magnetic reconnection. In our
laser-driven capacitor-coil experiment, the system size ($\sim$3 ion skin depths) places it in the electron-only regime. Yet, Thomson scattering reveals out-of-plane electron drift oscillations at the local lower-hybrid frequency, with kinetic energy density reaching $\sim$18% of the local
magnetic energy density. Linear theory with the measured parameters predicts more than ten e-folding times of growth, indicating that the instability reaches the nonlinear regime within the measurement window. Supported by particle-in-
cell simulations, these results demonstrate the importance of ions in the dissipation and energy transfer in electron-only reconnection where their significance has not been previously recognized.
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All authors B. K. Russell, K. Sakai, Y. Zhang, L. Gao, E. G. Blackman, W. Daughton, C. Dong, J. Katz, S. R. Klein, C. C. Kuranz, X. Li, X. M. Li, A. L. Milder, J. Ng, K. Orr, G. Pomraning, J. P. Schell, A. Stanier, J. Yoo, H. Ji
Quantum Physics
Parallel Quantum Advantage with Limited Adaptivity Requires Structure
Qipeng Liu and Saachi Mutreja
Aaronson and Ambainis (Theory of Computing, 2014) conjectured that
quantum query
algorithms admit efficient almost-everywhere classical simulation: for any $T$-query
quantum algorithm, its acceptance probability can be approximated on a $(1-\delta)$ fraction of inputs, up to $\epsilon$ additive error, using $\mathrm{poly}(T, 1/\epsilon, 1/\delta)$ classical queries. At a high level, the
conjecture suggests that exponential
quantum speedups are possible only on sufficiently structured inputs. In this work, we make progress on this
conjecture by proving it for
quantum algorithms that make massively parallel
quantum queries. In contrast, Yamakawa and Zhandry (Journal of the ACM, 2024) showed that
quantum algorithms restricted to parallel queries can still achieve exponential speedups over classical
algorithms for sampling problems. We establish our simulation
theorem by proving the stronger statement that parallel-query
quantum algorithms cannot distinguish the uniform distribution over oracles from oracles drawn from so-called "dense distributions". Our main technical contribution is a coupling
theorem that relates the uniform distribution over oracles to oracles drawn from dense distributions. We further extend this approach beyond the purely parallel setting. We prove simulation
theorems for
quantum algorithms with constant rounds of adaptivity, and for
quantum algorithms with a bounded
quantum-query prefix followed by a massively parallel
quantum-query stage.
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Cosmology and Nongalactic Astrophysics
A blind spot in transverse BAO calibration
Domenico Sapone
Transverse
baryon acoustic oscillation (BAO) measurements are increasingly used for cosmological inference, and carry a calibration that no such inference can constrain. A constant error in the transverse BAO scale is exactly degenerate with the combination $r_{\rm d} h$: it leaves the goodness of fit unchanged and the recovered parameters plausible, and is therefore invisible to any analysis that uses these measurements alone. The radial BAO sector removes this degeneracy, supplying $D_{\rm M}/r_{\rm d}$ by integration without reference to $H_0$ or to any model for the expansion rate. In flat Friedmann–Lemaître–Robertson–Walker (FLRW) geometry the relation between the two sectors is an identity, so the sound horizon and the dark-energy equation of state cancel as well. An integrated form of this identity reduces the consistency test to a straight line, whose slope measures a relative transverse calibration $\varepsilon$. A departure from $\varepsilon = 1$ cannot be produced by any dark-energy model, nor by spatial
curvature: it indicates an inconsistency in the measurement chain rather than in the cosmology. We apply the test to the two main SDSS transverse BAO compilations, which give $\varepsilon = 1.073 \pm 0.021$ and $1.021 \pm 0.029$. The first differs from unity at $3.8\sigma$ using the published independent errors, while the second is consistent with unity. The two compilations themselves differ by $(5.4 \pm 1.4)\%$, or $3.9\sigma$, and the offset is constant in
redshift. The test provides a direct diagnostic for current and future angular BAO measurements.
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High Energy Physics (Phenomenology)
QED radiative effects in semi-inclusive deep-inelastic scattering: traditional and factorized approaches
Igor Akushevich, Haiyan Gao, Alexander Ilyichev et al. (+5 more)
Semi-inclusive deep-inelastic scattering (SIDIS) of
leptons is a vital tool for probing the three-dimensional momentum space partonic structure of the nucleon. Reliable extraction of the intrinsic collinear or transverse momentum dependent parton distributions from SIDIS data requires careful treatment of QED radiative effects beyond the Born level. In this work we perform a detailed comparative analysis of QED effects in SIDIS using the traditional Bardin-Shumeiko approach, augmented by the electron structure function method, and a more recent factorized approach that treats QED and QCD radiation on equal footing. We compare analytical and numerical results of these approaches for the unpolarized $\pi^+$ electroproduction cross sections off the
proton and the Collins and Sivers transverse single-
spin asymmetries, and identify the sources of discrepancies between the calculations, which for the cross sections can reach up to $\approx 2\%$, $\approx 7\%$, and $\approx 5\%$ at Jefferson Lab, HERMES, and EIC kinematics, respectively. To provide a unified approach for reliably extracting partonic information from future SIDIS measurements, we propose a hybrid framework that employs the salient features of both frameworks in their respective regions of applicability.
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All authors Igor Akushevich, Haiyan Gao, Alexander Ilyichev, Shuo Jia, Vladimir Khachatryan, Youjie Lin, Tianbo Liu, W. Melnitchouk
Cosmology and Nongalactic Astrophysics
Non-Minimally Coupled Warm Inflation in the Defining Frame
Adrián Casado-Turrión, Paulo B. Ferraz, Mindaugas Karčiauskas et al. (+1 more)
Warm inflation in $F(\Phi)R$ scalar-tensor theories of
gravity is investigated in the `defining' frame, where the theory and its parameter values are specified. Translating the resulting dynamics to the Einstein frame, we find that the dissipation ratio is suppressed by the modified-
gravity effects. Thus, although the effective warm-inflation dynamics can be consistently analysed in either frame, the dissipative regimes need not coincide between them. In particular, we find that
quantum perturbations can dominate over thermal fluctuations in the scalar power spectrum even in a high-temperature, strong-dissipation regime in the defining frame. Finally, we compute the scalar spectral index and tensor-to-scalar ratio for a non-minimal coupling function $F(\Phi) = 1+\xi (\Phi/m_{\rm P})^2$ with a quartic potential and both constant and quadratic field-dependent dissipation coefficients, and identify
benchmark points compatible with current CMB constraints.
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All authors Adrián Casado-Turrión, Paulo B. Ferraz, Mindaugas Karčiauskas, José Jaime Terente Díaz
Quantum Physics
Programmable cavity QED with a fiber-integrated atomic array
Stephan Roschinski, Johannes Schabbauer, Franz von Silva-Tarouca et al. (+3 more)
Strong atom-
photon interactions in optical cavities are a key resource for
quantum information processing,
quantum networking, and the exploration of
quantum optical effects. Optical tweezer arrays offer scalable, site-resolved control of neutral atoms, but their integration with high-cooperativity cavity QED systems remains challenging. Here we combine a twelve-site $^{87}$Rb optical tweezer array with a high-cooperativity fiber Fabry-Pérot microcavity. The array is positioned within the cavity mode and individual sites are controlled with subwavelength precision, enabling continuous tuning of the single-atom coupling strength via deterministic displacement through the standing-wave field. For up to five atoms coupled to the cavity, we measure collectively enhanced
vacuum Rabi splitting and implement cavity-based non-destructive readout of the number of coupled atoms. These results establish a scalable architecture for cavity-mediated
entanglement generation and many-body cavity QED with single-atom control, and they lay the foundation for fiber-integrated
quantum network nodes.
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All authors Stephan Roschinski, Johannes Schabbauer, Franz von Silva-Tarouca, Marvin Holten, Damien Bloch, Julian Léonard
Cosmology and Nongalactic Astrophysics
Transient Early Dark Energy-Like Dynamics as a Mechanism for Enhanced Early Structure Formation in the JWST Era
Abhik Bhattacharjee, Amlan Chakraborty, Subinoy Das et al. (+2 more)
The discovery of massive
galaxies at
redshifts $z\gtrsim10$ by the James Webb Space
Telescope (JWST) has renewed interest in cosmological mechanisms capable of enhancing early structure formation while preserving the successful large-scale predictions of the standard $\Lambda$CDM model. We investigate a phenomenological scenario in which an exotic dark matter species can undergo a transient early dark energy-like phase during the radiation-dominated era ($10^{-7}\lesssim a\lesssim10^{-5}$) before reverting to pressureless cold dark matter. We utilize the generalized dark matter framework to model this species, which is restricted to a sub-percent fraction of the total dark matter component by CMB, BAO and Type Ia
supernova data. Its background and perturbation dynamics are characterized by a time-dependent equation of state, $w(a)$, and a time- as well as scale-dependent sound speed, $c_s^2(a,k)$. The temporary negative equation of state, combined with our phenomenological pressure-response prescription, induces a finite interval of negative effective sound speed squared. This triggers an instability-driven growth of density perturbations over a limited range of comoving scales, thereby enhancing the formation of early dark matter
halos. We find that the enhanced
halo abundance can substantially reduce the
star-formation efficiencies required to reproduce the observed abundance of JWST
galaxies relative to the standard $\Lambda$CDM scenario, especially at higher
redshifts. Our results demonstrate that transient early dark energy-like dynamics in a subdominant dark matter component provide a viable mechanism for enhancing early structure formation and offer a new framework for interpreting the abundance of high-
redshift galaxies observed by JWST and future surveys.
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All authors Abhik Bhattacharjee, Amlan Chakraborty, Subinoy Das, Anshuman Maharana, Priyank Parashari
Quantum Physics
Quantum-mechanical wave functions in singular potentials: linear and nonlinear states
Hidetsugu Sakaguchi and Boris A. Malomed
It is known that the attractive singular inverse-square potential gives rise to the critical
quantum collapse in the framework of the three-dimensional (3D) linear Schroedinger equation. This article summarizes theoretical results which demonstrate suppression of the collapse, caused by this singular potential, and the creation of the otherwise missing ground state (GS) in a 3D gas of bosonic particles, carrying an electric dipole moment, which are pulled to the central electric charge, with repulsive contact interactions between the particles. In the mean-field approximation, the repulsive interactions are represented by the cubic term in the respective Gross-Pitaevskii (GP) equation. In addition to the GS, excited states with angular momentum are briefly considered too. Another topic considered in the article is 1D and 2D bound states in the linear Schroedinger and GP equations with the repulsive potential, which demonstrates a singularity at r –> infinity. A very recent result is that such a potential, growing faster than the negative harmonic-oscillator potential, produces a full spectrum of counter-intuitive normalizable (localized) bound states. The article puts forward perspectives for further studies of linear and nonlinear bound states existing under the action of the potentials with the singularity at r –> 0 or r –> infinity.
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Optics
Point Spread Function Engineering Using Implicit Neural Representations
Suet Ying Chan, Mitchell Gilmore, Qilin Deng et al. (+4 more)
Point spread function (PSF) engineering through pupil plane modulation is a technique used in microscopy to achieve specific imaging properties, such as depth encoding or extended depth of field. Existing PSF design methods often rely on extensive domain knowledge and task-specific basis functions, making it difficult to generalize across different applications. We treat the PSF engineering task as a phase
retrieval problem and propose a neural field pupil design method that optimizes a phase profile for any arbitrary, user-defined 3D PSF distribution. This provides a flexible framework for 3D PSF engineering for various applications with implicit regularization that proves robust to initialization compared to pixel-wise optimization methods
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All authors Suet Ying Chan, Mitchell Gilmore, Qilin Deng, Guorong Hu, Joseph Greene, Ruipeng Guo, Lei Tian
Chaotic Dynamics
Flip rate prediction in the double pendulum
Peleg Haham and Barak Kol
The intermediate-energy double pendulum is a prototypical chaotic system. Despite its irregular motion, it exhibits recurrent flips - events in which one of the arms passes over the top. We develop a statistical prediction for the mean flip rate in terms of phase space flux. Applying this flux-based approach to the equal-mass, equal arm ("egalitarian") double pendulum, we find excellent agreement between the statistical prediction and numerical simulations: ensemble-averaged flip rates agree at about the 1% level, while even the statistics of individual chaotic trajectories agree at the few-percent level, quantifying the validity of the ergodic approximation. This agreement holds for flips of either arm and over a broad range of energies. This flux-based approach is closely related to that used for the egalitarian three-body system. A central role is played by the saddle orbits: periodic orbits that tend to the stable saddle eigenmode as the energy approaches the saddle energy from above and approximately follow the ridge of the potential at higher energies. These orbits provide a natural dividing surface for defining flips while avoiding recrossings. Indeed, the resulting distribution of crossing times exhibits a distinct gap. We also present two alternative simplified dividing surfaces, one of which is based on an accurate analytic approximation to the saddle orbits.
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Quantum Physics
Analytical Solutions of the Generalized Klein-Gordon Oscillator in Som-Raychaudhuri Space-Time via the Extended Nikiforov-Uvarov Method
Hale Karayer, Tolga Celik and Dogan Demirhan
In this study, we present an analytical approach based on the extended Nikiforov-Uvarov method to solve the generalized Klein-Gordon oscillator in the presence of a uniform
magnetic field within the Som-Raychaudhuri space-time. Exact eigenstate solutions are obtained for two distinct potential models, namely the linear potential and the Cornell potential. The corresponding energy
eigenvalues are determined, and the associated eigenfunctions are analyzed and illustrated graphically.
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Strongly Correlated Electrons
Nonlinear Drude weight of the one-dimensional Hubbard model
Tetsuya Iwasaki and Hosho Katsura
We investigate nonlinear Drude weights (NLDWs) in the one-dimensional repulsive Hubbard model at zero temperature by combining exact Bethe-ansatz calculations with low-energy effective field theory. At quarter filling, we first derive the strong-coupling expansion of the NLDWs and confirm it numerically over a wide range of interaction strength. We then compare the numerical results with the prediction of the Tomonaga-Luttinger
liquid (TLL) description including irrelevant perturbations. While band-
curvature corrections yield finite contributions to higher-order NLDWs, the Umklapp interaction predicts divergent NLDWs when the order $n$ of the Drude weight exceeds a threshold determined by the TLL parameter. In contrast, finite-size scaling of the exact Bethe-ansatz results indicates that all calculated NLDWs remain finite in the thermodynamic limit, revealing a discrepancy between the exact results and the predictions of the low-energy effective field theory. At half filling, we analyze the finite-size scaling of the NLDWs across the Mott metal-
insulator transition. We derive their asymptotic behavior in the insulating phase and propose a hyperscaling ansatz for NLDWs near the critical point, which is verified numerically. Our results clarify the interaction dependence and critical scaling of nonlinear transport coefficients in the one-dimensional Hubbard model and highlight limitations of the conventional low-energy effective description for higher-order transport.
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Statistical Mechanics
Learning Potts Models and $Z_3$ Toric Codes: Higher and Ordinary Nishimori Criticality
Rushikesh A. Patil, Malte Pütz, Rohit Mukherjee et al. (+3 more)
Motivated by a previous Ising study, we identify a ${\it higher}$ Nishimori line in the learning phase diagram of the $2D$ $q$-state Potts model $(2 < q\leq 4)$ under bond-energy measurements. This ${\it higher}$ Nishimori line meets the critical temperature line of the Potts model, in a ${\it higher}$ Nishimori critical point – a tricritical point at finite inference strength that separates a paramagnetic, a
ferromagnetic and a '
spin-glass' phase. With analytical tools, we discuss the general structure of the rich phase diagram, which contains two unstable and three stable fixed points, and obtain a number of exact results for universal quantities, including the decay exponent of the Edwards-Anderson correlator, using a Gaussian measurement protocol which allows for exact calculations. Using extensive numerical tools, we confirm these statements for a generic, discrete $q$-state measurement protocol and determine precise numerical estimates for the location of higher and ordinary Nishimori critical points as well as RG flows between the various fixed points. We also discuss the Casimir effective central charges of the critical points in the learning phase diagram, and their monotonic ${\it decrease}$ along measurement-induced RG flows, as established non-perturbatively by the c-effective
theorem and its extensions, and contrast it to the monotonic increase along the corresponding RG flows in the random-bond Potts model. Finally, we discuss a general argument based on ${\it Elitzur's \; theorem}$ that establishes stability of the ordinary Nishimori critical points in their respective learning phase diagrams. Equivalently, our results describe a monitored deformed $\mathbb{Z}_q$ toric code where the tricritical ${\it higher}$ Nishimori point is an 'information' critical point that separates stable
quantum, classical, and no
memory phases.
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All authors Rushikesh A. Patil, Malte Pütz, Rohit Mukherjee, Guo-Yi Zhu, Simon Trebst, Andreas W. W. Ludwig
High Energy Astrophysical Phenomena
Probabilistic kilonova prediction from gravitational wave inferred binary neutron star parameters
Xiao-Fei Dong, Ik Siong Heng, Gavin P. Lamb et al. (+10 more)
Kilonovae provide a key electromagnetic window into binary
neutron star mergers, revealing the properties of the merging system while probing r-process nucleosynthesis of the Universe. However, only a few kilonova candidates have been detected to date, with AT2017gfo being the only one associated with a gravitational wave event, GW170817. In this work, we present Genova, a probabilistic framework for predicting kilonova spectra and light curves directly from gravitational wave posterior samples of binary
neutron star mergers. This method uses a conditional normalising flow to learn the distribution of rest-frame spectra conditioned on the source-frame component masses,
tidal deformabilities, viewing angle and time since merger. Other kilonova model parameters, such as ejecta opacities, are marginalised over during training, so that their effects are propagated into the predicted spectra as predictive uncertainty. In the self-consistency test, the flow model reproduces the median light curves with residuals typically below $\sim 0.1$ mag, and the ratio of the predicted central 68% interval widths remains predominantly between $0.8$ and $1.4$ over $\sim 0.4$–$8.0$ days. Comparisons with a physically distinct kilonova model show that the probabilistic prediction can remain informative beyond the model used for training. We apply Genova to GW170817/AT2017gfo using multi-band observations, including newly re-reduced $Y$-, $J$-, $K_s$-band photometry from the Visible and Infrared Survey
Telescope for Astronomy, which we present in this work. The resulting predictive intervals broadly encompass the observations while capturing both gravitational wave posterior uncertainty and the variation induced by marginalised kilonova model parameters.
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All authors Xiao-Fei Dong, Ik Siong Heng, Gavin P. Lamb, Chris Messenger, Nikhil Sarin, Benjamin Rayson, Nial R. Tanvir, Jessica Irwin, Thomas Wallace, Skye Rosetti, Bo Milvang-Jensen, Andrew J. Levan, Jens Hjorth
Chemical Physics
Vibrational Activation Triggers Ultrafast Excited State Intramolecular Proton Transfer in Single-Benzene Fluorophores
Brieuc Le Dé, Simon Huppert, Riccardo Spezia et al. (+1 more)
Single-benzene fluorophores (SBFs) are exceptionally light-weight
quantum emitters which have recently been shown to display Excited State Intramolecular
Proton Transfer (ESIPT) and highly tunable dual-fluorescence that could be exploited for multiple applications. Here, we employ excited-state molecular dynamics to investigate the ultrafast dynamics of ESIPT in two different SBFs, one of which with a new structure proposed in this work. We find that both single and double ultrafast
proton transfers can be triggered by exciting specific molecular vibrations. Strikingly, the kinetic activation of these vibrations - selected by atomistic,
symmetry-based analysis - can considerably enhance the yield of
proton transfer(s), as well as direct the reaction towards either single or double-transfer products. In-depth analysis elucidates the origins of this vibronic control, providing atomistic guidelines through which both the rate and fate of ESIPT could be steered using ultrafast IR-Vis spectroscopies.
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All authors Brieuc Le Dé, Simon Huppert, Riccardo Spezia, Alex W. Chin
Applied Physics
Acoustic Resonance Distribution for Core-Shell Scatterers
Naruna E. Rodrigues, Gilberto Nakamura, Odemir M. Bruno et al. (+1 more)
Acoustic metamaterials can exhibit unusual effective properties through mechanisms such as energy localization and resonant behavior in their constituent building blocks. Here, we investigate the internal acoustic energy of fluid core-shell spheres and map how resonances emerge from the interplay between material contrasts and shell geometry. The resulting phase diagram reveals an organized resonant landscape across distinct impedance-contrast regimes. From this structure, we obtain two compact predictive relations: one for resonance existence and another for spectral recurrence of successive peaks. Together, they enable the rapid identification of material and
geometric combinations associated with targeted resonance responses. The framework is further tested against representative systems from the literature, reproducing their observed behavior. These results provide a physics-based route for screening and tailoring resonant core-shell building blocks before full-wave numerical simulations.
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All authors Naruna E. Rodrigues, Gilberto Nakamura, Odemir M. Bruno, Alexandre S. Martinez
Mathematical Physics · Cross-listed from math.PR
Notes on Hydrodynamic Limits and Related Topics
Sunder Sethuraman
In these lecture notes, we discuss various `hydrodynamic LLN' and `CLT' scaling limits, among others, in types of
stochastic interacting particle systems, connecting `microscopic' behaviors to continuum laws. Via `short stories', the aim is to present some of the `basics' for students and those entering the field, as a complement to books such as Kipnis-Landim 1999, Komorowski-Landim-Olla 2012, Liggett 1985, Liggett 1999. To be concrete,
attention is restricted to a few `mass conservative' systems on discrete spaces, namely exclusion and zero-range processes, that have proved robust in the study of different phenomena. After preliminaries, we discuss the `
entropy' and `relative
entropy' methods to prove hydrodynamic limits of the bulk mass in finite volume, as well as other items such as construction of systems in infinite volume and the structure of their invariant measures, and scaling limits of local functionals, such as occupation times of sites and the motion of a tagged particle. In the last part, we also discuss
equilibrium fluctuations of the bulk mass when the process starts from an invariant measure.
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Quantum Physics
Logarithmic depth compression of Heisenberg Hamiltonian simulation by fan-out parallelization, with built-in error detection
Artemiy Burov and Clément Javerzac
Noisy intermediate-scale
quantum computers are constrained by
circuit depth, while product-formula simulation of
spin systems leads to narrow and deep
circuits. Here we introduce a fan-out-based gadget compiler that trades
circuit depth for width in simulations of Heisenberg-type
nuclear magnetic resonance (NMR)
Hamiltonians. Each logical
spin is encoded into a small repetition-code register sized by its interaction degree, so that all pairwise interactions of a given Pauli type execute in parallel after a logarithmic-depth CNOT fan-out, and the redundant registers provide error detection for post-selection at no additional algorithmic overhead. The central result is a fixed-protocol resource comparison of the two compilations, transpiled to heavy-hex superconducting and all-to-all trapped-ion targets across a set of NMR
spin systems. For interaction graphs with a high-degree hub the volume-optimal schedule halves the two-
qubit depth and reduces the volume 1.7-fold for the 13-
spin demonstration, which on heavy-hex also lowers the two-
qubit gate count, and the depth reduction rises to 2.5-fold on all-to-all for the highest-degree molecule studied. On all-to-all the two-
qubit gate count rises for every system, so the volume reduction is a benefit on depth-limited hardware. The gain grows with the degree inhomogeneity of the interaction graph and vanishes for dense uniform graphs, where the optimum is the sequential
circuit. We simulate the zero-field NMR spectrum of tetramethylsilane, a 13-
spin star system. Under a noise model scaled from a published present-day processor calibration, the shallower gadget
circuits match or surpass the sequential compilation only after post-selection on their built-in error detection, once error rates improve by one to one and a half orders of magnitude. We verify the spectra against an independent classical computation.
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Quantum Physics
Jamming Extensions of Quantum Correlations Lead to Hidden Superluminal Signaling
Ravishankar Ramanathan, Xie Sicheng, Michał Eckstein et al. (+1 more)
Relativistic causality in certain spacetime configurations permits jamming - superluminal causal influences that nevertheless do not enable superluminal signaling. We fully characterize the correlations compatible with relativistic causality (RC) by extending the operator framework of PRL 104, 140404. When the underlying state is required to be
quantum, we prove that any nontrivial jamming - whether state-independent or state-dependent - necessarily leads to hidden superluminal signaling. Thus, the only consistent possibilities are standard
quantum correlations without jamming or the full relativistically causal correlation set, with intermediate jamming extensions of
quantum correlations leading to signaling. As an application of our characterization, we investigate the security of device-independent (DI) cryptographic primitives against adversaries constrained only by relativistic causality. We construct explicit RC attacks that break DI bit commitment and DI secret sharing in jamming geometries, even when these protocols remain secure against no-signaling adversaries. Our results show that security against relativistic adversaries requires behaviors to be specified together with the spacetime locations of their measurement events; input-output statistics alone are insufficient.
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All authors Ravishankar Ramanathan, Xie Sicheng, Michał Eckstein, Paweł Horodecki
Mesoscale and Nanoscale Physics
Coulomb blockade-like transport and enhanced memory in organic transistors embedded with sub-nm Pt nanoparticles for neuromorphic computing
Arash Ghobadi, Thomas B. Kallaos, Abhi Abhijeet et al. (+5 more)
Organic transistors are playing an increasingly important role for neuromorphic applications. However, devices that rely solely on ferroelectric switching or on interface traps for their multi-conductance states exhibit limited
memory windows. Here, we introduce an ultrathin
oxide layer with a uniform distribution of sub-nm platinum nanoparticles (PtNPs) at the interface of a
polymer semiconducting and a ferroelectric dielectric in a thin film transistor architecture. The interfacial stack, Al$_2$O$_3$/PtNP/Al$_2$O$_3$, provides a viable route for localized charge trapping and de-trapping in a region where it can most effectively influence the channel conductance. The organic transistors display a large
memory window (> 20 V) in their current-voltage characteristics. The sub-nm PtNPs give rise to features that are consistent with room temperature Coulomb blockade-like transport, supporting discrete and well-separated levels within the
memory window. The devices support
multimodal programming using electrical and optical stimuli with both long-term plasticity and enhanced short-term plasticity (STP) phenomena. These results open new directions for implementing STP in the development of neuromorphic computing.
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All authors Arash Ghobadi, Thomas B. Kallaos, Abhi Abhijeet, Stephen C. Klue, Joseph C. Mathai, Carsten A. Ullrich, Shubhra Gangopadhyay, Suchismita Guha
High Energy Physics (Phenomenology)
Extraction of DVCS amplitudes off the nucleon
C. Mezrag, P. Sznajder and J. Wagner
This work presents a modern extraction of deeply virtual Compton scattering (DVCS) amplitudes off the
proton and off the
neutron through a global analysis of experimental data. These amplitudes serve as a crucial intermediate quantity linking generalized parton distributions (GPDs) to experimental observables. The analysis relies on a novel extraction framework recently integrated into the PARTONS software ecosystem. We employ two distinct modelling approaches for the DVCS amplitudes, both utilizing machine learning techniques: one model-agnostic and the other theory-augmented. For the first time, we incorporate the extraction of helicity-flip amplitudes, which are particularly sensitive to higher-twist effects. Furthermore, we compare our extracted amplitudes to timelike Compton scattering (TCS) data using the established relations between DVCS and TCS, serving as an important test of universality of GPDs. We also extract the DVCS subtraction constant, for which ab initio predictions from
lattice QCD have been obtained. This allows us to confront these predictions with DVCS data for the first time, initiating a new virtuous cycle between first-principles theory and phenomenology.
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