Quantum Physics
Exact polariton-condensate states via nonlinear Stark coupling
DaKai He and Zhi Song
We study a hybrid system of coupled cavities, with or without two-level atoms doped inside. By employing a building-block construction facilitated by nonlinear Stark coupling, we identify a
manifold of exact many-body eigenstates that remain analytically tractable across arbitrary
lattice geometries and atom distributions. We demonstrate that these exact states exhibit a dual physical nature depending on their spectral positioning: when embedded within the chaotic many-body spectrum, they manifest as
quantum scars that violate the eigenstate thermalization hypothesis and undergo weak ergodicity breaking; conversely, as ground states within fixed-total-excitation sectors, they exhibit off-diagonal long-range order and form polariton condensates. Furthermore, numerical calculations of local excitation-number fluctuations suggest that negative Stark coupling shifts the Mott-
insulator to superfluid transition toward weaker inter-cavity hopping. Our findings provide a versatile framework for engineering both coherent
quantum phases and non-thermalizing states in diverse light-matter architectures.
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Materials Science
Localization of Candidate Kikuchi Regions in RHEED Images: Visibility and Annotation Boundaries
Lumou Weng, Hanshan Huang, Zhenhan Zhang et al. (+1 more)
Kikuchi lines and bands in reflection high-energy electron diffraction (RHEED) carry information on
crystal geometry and electron scattering, but are often obscured by intense diffraction streaks. We combine multiscale convolution with spatial detail from skip connections and independent supervision that allows overlapping regions to localize streaks and candidate Kikuchi regions separately. Using manual polygon annotations made before model-assisted editing, the Kikuchi intersection-over-union (IoU) on 29 laboratory test images from separate growth batches was $0.6290 \pm 0.0137$. We then performed supervised adaptation to public chalcogenide images and stratified images by Kikuchi visibility using the median ratings of three observers who rated the images separately, two of whom rated with predictions hidden. With all 244 training images, IoU for the clear-feature group of 10 test images was $0.5014 \pm 0.0336$, whereas ambiguous images gave lower values. With 100 training images, clear-group IoU was $0.5171 \pm 0.0073$; expanding the training set also reduced responses on images without target features. Reported uncertainties are sample standard deviations across four laboratory runs or three adaptation runs. Public-image adaptation used reference masks of mixed provenance, including prediction-derived drafts. The method converts visual cues into inspectable spatial regions, providing a basis for analysis of line positions, intersections, and local intensity.
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All authors Lumou Weng, Hanshan Huang, Zhenhan Zhang, Gan Wang
Quantum Physics
High-Rate Concatenated Quantum Error-Correcting Codes for Qudits
Takanori Nishi and Hayato Goto
Qudits provide a larger local
Hilbert space than
qubits and have recently attracted interest as building blocks for efficient fault-tolerant
quantum computation (FTQC). In this work, we extend many-hypercube (MHC) codes, high-rate concatenated
quantum codes, from
qubits to qudits of
prime dimension $q$. We construct the level-2 and level-3 MHC codes with parameters $\left[\!\left[6^2,4^2,2^2\right]\!\right]_q$ and $\left[\!\left[6^3,4^3,2^3\right]\!\right]_q$, respectively, and generalize the level-by-level minimum-distance (LLMD) decoder originally proposed for the
qubit MHC codes. In a qudit $X$-error model, we evaluate the code-capacity performance of the qudit MHC codes for dimensions up to $q=13$. We find that the error threshold increases monotonically with the local dimension $q$, reaching $10.0\%$ for $q=13$, nearly double the value of $5.1\%$ for
qubits. Furthermore, for sufficiently large local dimensions, we observe a pronounced waterfall regime in which the logical error rate decreases substantially faster than expected from conventional distance-based estimates. To understand the origin of the observed qudit advantage, we analyze the decoding performance in terms of the
entropy of the underlying $q$-ary noise channel. This analysis reveals a competition between the increased syndrome information available at larger $q$ and the simultaneous growth of the typical physical error weight at fixed
entropy. These results demonstrate that higher-dimensional
quantum systems can substantially improve the performance of high-rate concatenated
quantum codes and motivate further development of qudit-based FTQC architectures.
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Materials Science
Giant Magnetization Enhancement at Ultrathin Limit of an Orthoferrite
Jin Young Oh, Yaolong Xing, Seung Gyo Jeong et al. (+18 more)
Low-dimensional
magnetic systems have received significant interest due to their high scalability and energy efficiency for future electromagnetic applications. However, low-dimensional magnetism at finite temperature is subject to Mermin-Wagner fluctuations, which make its realization highly challenging. Here, we propose structural modulation in the thin-film structure of an orthoferrite system to achieve a high low-dimensional
magnetic response at room temperature. ErFeO3 epitaxial thin film with atomically precise thickness control demonstrates that the
magnetic response at 300 K can be significantly enhanced compared to its bulk counterpart. The
magnetic response reaches its maximum value of 3.7 MuB/f.u. for the 2 nm-thick epitaxial film. The characteristic domain structure resulting from epitaxial strain and orbital reconstruction at the surface, both arising from the thin film geometry, has been proposed as the microscopic origin of the giant magnetization enhancement. We show that
magnetic ordering can indeed be realized in the 2D limit, with deliberate structural control of orthoferrite systems.
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All authors Jin Young Oh, Yaolong Xing, Seung Gyo Jeong, Sehwan Song, Woo-suk Noh, Valeria Lauter, Seongjae Choi, Seyoung Kwon, Jaeha Choi, Si Won Kim, Hong Hyun Jeon, Heemin Lee, Cheng-Tai Kuo, Jun-Sik Lee, Chanyoung Lee, Yeonkyu Lee, Jeehoon Kim, Heung-Sik Kim, Sungkyun Park, Sang Ho Oh, Woo Seok Choi
Materials Science
Light-induced interlayer spacing dynamics via orbital phonon coupling
Wenwen Mao, Hanbyul Kim, Angel Rubio et al. (+1 more)
Interlayer coupling controls the electronic properties of layered van der Waals transition metal dichalcogenides. We investigate light-induced control of the interlayer spacing through orbital-selective excitation in trilayer 1T'-WSe2 and 1T'-WS2. Real-time time-dependent density functional theory simulations show that the interlayer spacing contracts or expands depending on whether chalcogen p-orbital density is depleted from or accumulated in the interlayer region. Effective Lindblad models coupled to the
lattice dynamics reproduce these contrasting responses with simplified dynamics. A single effective excited state captures the cosine-like displacive motion in trilayer 1T'-WSe2, whereas the shift of the
equilibrium spacing in trilayer 1T'-WS2 requires two excited states with different electron-
phonon couplings and relaxation channels. Static calculations at varied interlayer spacings indicate that these spacing changes modify the electronic gaps and could access different electronic phases. These results connect orbital redistribution, carrier relaxation, and interlayer breathing motion, and establish orbital-selective optical excitation as a route to tuning the electronic properties of layered materials.
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All authors Wenwen Mao, Hanbyul Kim, Angel Rubio, Dongbin Shin
General Relativity and Quantum Cosmology
Chameleon Gravity with an Environmental Frequency Dependent on Density
Raziyeh Zaregonbadi and Nasim Saba
Scalar field theories of modified
gravity are strongly constrained by the absence of detectable long range fifth forces in laboratory and Solar System environments. The chameleon mechanism addresses this problem by making the
equilibrium value and effective mass of the scalar field dependent on the ambient matter density. In this work, we investigate an effective phenomenological extension of the chameleon framework in which the scalar potential contains an additional quadratic environmental contribution characterized by a density dependent background frequency. This background frequency is distinct from the frequency of scalar perturbations and parametrizes unresolved environmental effects beyond the conventional matter coupling. For an inverse power law scalar potential, we derive the modified
equilibrium configuration and identify a frequency dominated regime in which the environmental contribution controls the density dependence of the field. Linear perturbations about the environmental minimum obey a Klein Gordon dispersion relation with a density-dependent effective mass, and the absence of tachyonic instability requires a positive environmental coupling. We further derive analytical consistency conditions associated with frequency dominance, thin shell screening, fifth-force suppression, and the weak field approximation. Numerical illustrations for representative parameter choices demonstrate how the modified density scaling can enhance fifth-force suppression relative to the conventional chameleon case.
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Cosmology and Nongalactic Astrophysics
Pinpointing the cosmic web between massive galaxy clusters I. The incidence of HI and OVI as WHIM tracers
Karen Martínez-Acosta, Nicolas Tejos, Ismael Pessa et al. (+6 more)
At
redshift z<1, the $\Lambda$CDM paradigm predicts that $\sim$40-50% of baryons reside in the warm-hot intergalactic medium (WHIM) within
cosmic web filaments. Characterizing the physical state and distribution of this dominant baryonic component is crucial for a complete picture of baryon
evolution in the low-
redshift Universe. However, directly observing the WHIM has been challenging due to its low density and high temperature and ionization state. Absorption-line spectroscopy offers a promising approach, particularly through analyses of broad Ly-$\alpha$ absorbers (BLAs; Doppler parameter b>40 km/s) and OVI absorbers. This work focuses on probing WHIM signatures by analyzing the incidence rates of these tracers in and around putative
cosmic web filaments connecting massive
galaxy clusters. We use far-ultraviolet (FUV) absorption spectroscopy from HST/COS along ten QSO sightlines at z<1, selected for their proximity in projected distance and velocity to cluster pairs. We focus on absorption features of WHIM tracers (BLAs and OVI) and cold-gas tracers (narrow Ly-$\alpha$ absorbers, or NLAs; b<40 km/s), which are used as a control sample for colder gas. We measure excess incidence rates for total HI, NLAs, BLAs, and OVI within a rest-frame $\Delta v=\pm1000$ km/s and an impact parameter $\Delta d<3$ Mpc relative to the field expectation, and find that the excesses of BLAs and OVI are about twice those of NLAs. Additionally, the covering fractions of BLAs and OVI appear larger by factors of $\sim$1.7 and 1.8, respectively, than in a random field control sample, whereas the NLA covering fraction is consistent with the random expectation. The larger relative excess of WHIM tracers compared to cold-gas tracers near independent cluster pairs indicates the prevalence of warm-hot gas in these environments, representing a potential signature of WHIM detection in inter-cluster filaments.
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All authors Karen Martínez-Acosta, Nicolas Tejos, Ismael Pessa, J Xavier Prochaska, Joseph Burchett, Britton Smith, Jessica Werk, Nelson Padilla, Sebastián López
Quantum Physics
Retromorphic Testing of Quantum Compiler Passes
Mushahid Khan and Olivia Di Matteo
Quantum compilers play a critical role in transforming high-level
quantum programs into optimized, hardware-compatible
circuits. However, verifying the correctness of compiler passes remains challenging, as determining the expected output of large, deeply entangled
quantum circuits is computationally intractable. This challenge is further amplified when compiler passes modify already complex
circuit structures, making manual validation of transformed
circuits impractical. In this work, we perform a systematic analysis of unit tests for
quantum compiler passes in four
quantum programming frameworks (PennyLane, Qiskit, Cirq, and pytket). Our findings indicate validation is dominated by program-content and program-metric assertions, and test
circuits are generally small and shallow. Motivated by these observations, we introduce a testing methodology for automated validation of
quantum compiler passes based on retromorphic testing and principles from the Hadamard test. This methodology analyzes a compiler pass, test
circuit, and expected pass behavior to verify semantic preservation and intended structural modifications. We implement our methods in a framework, RetroQ, and apply it to compiler passes in PennyLane and Qiskit. Experimental evaluation reproduced several existing bugs as well as uncovered previously undetected defects, such as flawed symbolic parameter handling, incorrect commutation logic, failure to recognize self-adjointness of gates, and runtime crashes. These findings highlight the need for compiler-pass-specific testing methodologies to improve the reliability of the evolving
quantum software stack.
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High Energy Physics (Phenomenology)
Implications of tachyonic phase transition in classically scale invariant general $U(1)_{X}$ models
Arindam Das, Katsuya Hashino, Yuta Orikasa et al. (+1 more)
We investigate the complementarity between
collider searches and gravitational-wave (GW) observations in the classically scale-invariant general $U(1)_X$ extension of the Standard Model. The $U(1)_X$ scale is generated radiatively through the Coleman-Weinberg mechanism, while the electroweak scale is induced through the
Higgs portal, without explicit mass terms in the scalar potential. Three right-handed
neutrinos are introduced to ensure anomaly cancellation and acquire Majorana masses upon $U(1)_X$
symmetry breaking, which also generates the mass of the neutral gauge
boson $Z'$. In the strongly supercooled regime, a tachyonic $U(1)_X$ phase transition can produce a
stochastic GW background. Assuming three heavy Majorana
neutrinos, we study their effects on the phase-transition dynamics and reheating, and estimate the resulting GW signals. We identify the regions of the $U(1)_X$ gauge coupling and $Z'$ mass accessible to future GW observatories, including LISA and DECIGO, and compare them with existing LEP and LHC constraints. We find that GWs from tachyonic phase transitions can probe regions with small gauge couplings and heavy $Z'$
bosons that are difficult to access through
collider searches, demonstrating the complementarity of these probes.
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All authors Arindam Das, Katsuya Hashino, Yuta Orikasa, Masanori Tanaka
Mesoscale and Nanoscale Physics
Cooperative STT and SOT switching in perpendicular magnetic tunnel junctions: Role of the pulse-end magnetization state
Zeyi Zhu, Ding Ma, Kai Zhang et al. (+11 more)
Spin–orbit torque MRAM (SOT-MRAM) is a leading candidate for next-generation nonvolatile
memory, offering high speed, endurance, and architectural compatibility. However, in conventional SOT switching, the magnetization remains near the in-plane region at pulse termination, making the final state highly sensitive to post-pulse relaxation dynamics and prone to back-switching. To overcome this, we propose a field-free scheme in which the transverse SOT drives large-angle precessional excitation while the perpendicular
spin-transfer torque (STT) biases the trajectory toward the reversed $-z$ state. Micromagnetic simulations reveal a nonlinear switching boundary in the $J_{\mathrm{STT}}$–$J_{\mathrm{SOT}}$ parameter space, originating from the distinct dynamical roles of the two torques: SOT primarily governs the excitation and crossing of the dynamical separatrix, whereas STT controls the terminal trajectory and final-state selection. An analytical macrospin model, based on the stability analysis of the current-induced
equilibrium, reproduces the critical-boundary trends as functions of current density, Gilbert damping $\alpha$, and uniaxial anisotropy $K_\mathrm{u}$, and distinguishes dynamic anti-damping and static instability branches. Systematic analyses of pulse duration, damping, anisotropy, and the STT–SOT balance further demonstrate that reliable ultrafast switching requires not only sufficient excitation to cross the separatrix before pulse termination, but also precise control of the pulse-end magnetization state to minimize post-pulse relaxation. These results establish that the pulse-end state, rather than the instantaneous torque amplitude, is the decisive factor governing switching speed and reliability in coupled STT–SOT systems.
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All authors Zeyi Zhu, Ding Ma, Kai Zhang, Mingwei Wu, Yi Huang, Jiarui Niu, Shuai Zhang, Mengdi Yin, Ka-San Mak, Lina Chen, Bo Liu, Tiejun Zhou, Yongbing Xu, Ronghua Liu
Solar and Stellar Astrophysics
Direct Numerical Comparison of Data Driving Strategies for Solar Flux Emergence in Magnetohydrodynamics: B-driving vs E-driving
Kyriakos Christos Tapinou, Axel Raboonik, David I. Pontin et al. (+3 more)
Data driving is an important technique for modelling realistic
magnetic field and
plasma evolution in regions of the solar atmosphere where direct observations are either absent or insufficient. This technique uses observational data to drive the
evolution of the simulation, while the modelled solar atmosphere evolves self-consistently. A common approach for data-driven simulations is B-driving, which uses the observed
magnetic field at the surface of the Sun as a boundary condition. However, only prescribing B at the boundary does not generally determine its numerical
evolution when the update depends on the reconstructed interface states or fluxes. To address this, E-driving provides an alternative approach by instead driving the simulation using the electric field on the boundary, which directly controls the
magnetic field update. We systematically quantify the performance of B- and E-driving in a controlled set of numerical experiments. We test both methods in the Athena++ solver using (a) an analytical flux-emergence model (Y. Fan & S. Gibson 2003) and (b) a "ground-truth" reference simulation (S. Toriumi & S. Takasao 2017; S. Toriumi et al. 2020) of active region emergence. For E-driving, the electric field is incorporated into Athena++'s constrained-transport (CT) update, preserving the discrete solenoidal constraint. We assess the reproduction of (i) boundary
magnetic flux, (ii) relative
magnetic helicity, (iii) total and free
magnetic energy, and (iv)
magnetic morphology. Across these diagnostics, E-driving gives better overall reproduction of the reference
evolution than B-driving. For the configurations considered in an Eulerian CT scheme, E-driving is more accurate than the commonly used ghost-
cell B-driving strategies and simpler than constructing an update-consistent B-driving boundary condition.
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All authors Kyriakos Christos Tapinou, Axel Raboonik, David I. Pontin, Michael S. Wheatland, Mark C.M. Cheung, Hannah Schunker
Optics
Optical Signals Synthesized from an Optical Lattice Clock with Uncertainty of 1.3E-17
Yuan Yao, Jinpeng Zou, Haosen Shi et al. (+3 more)
We report an accurate optical frequency synthesizer, which can generate single-frequency
laser light with high frequency stability and accuracy at desired frequencies over a wide optical region. The frequency of the output signal is divided from an 171Yb optical
lattice clock via an accurate optical frequency divider based on an optical frequency comb. Therefore, the output of the optical frequency synthesizer inherits the frequency accuracy from the Yb optical clock. The frequency uncertainty of the 171Yb optical
lattice clock is evaluated to be 6.8 mHz, corresponding to a fractional frequency uncertainty of 1.3E-17, mainly limited by the blackbody radiation shift and the
lattice-induced light shift.
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All authors Yuan Yao, Jinpeng Zou, Haosen Shi, Hongfu Yu, Longsheng Ma, Yanyi Jiang
High Energy Physics (Phenomenology)
Analysis of p-Wave Sommerfeld Resonance Behavior in Finite-Size Dark Matter
Wu-Long Xu, Jin Min Yang and Rui Zhu
Different stages of
cosmic evolution impose different requirements on the dark matter annihilation cross section. Sommerfeld enhancement provides a possible way to accommodate them. However, in the point-like dark matter scenario, satisfying these requirements with either $s$-wave or $p$-wave Sommerfeld enhancement can strongly constrain the dark matter and mediator masses and their coupling. A finite dark matter size introduces an additional parameter and may relax these constraints. Motivated by this possibility, in this work we study the $p$-wave Sommerfeld resonances of finite-size dark matter (like
proton or
neutron) without specifying its internal structure. We find that the $p$-wave contribution can exceed the $s$-wave contribution. Nevertheless, the finite-size $p$-wave resonances are weaker than those in the point-like case. Despite this suppression, their velocity dependence remains similar to that of point-like dark matter. We then extend our analysis to nugget dark matter composed of a small number of constituents. In this case, the $p$-wave Sommerfeld enhancement exhibits behavior similar to that of point-like dark matter.
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Mathematical Physics
Uniformity theory of weighted composites
Marcelo Epstein and Mohammadjavad Javadi
By including spatially varying volume fractions of the constituents, composites are obtained that are akin to functionally graded media. An extension of the mathematical apparatus of double groupoids is proposed to incorporate these materials with the aim of eventually classifying defects of misalignment and their time
evolution.
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Physics and Society
Energy-barrier characterization of secured basins in coupled oscillators with inertia
Jaiyong Lee, Daekyung Lee, Seung-Woo Son et al. (+3 more)
The second-order Kuramoto model captures rotor dynamics relevant to synchronization in power grids. In actual power grids, violation of angle-stability limits can trigger protective actions that are not included in the model, restricting its validity to trajectories that remain within these limits. We therefore define the secured basin as the region of disturbance space comprising disturbances whose trajectories remain within the angle-stability limits throughout the transient. We then characterize the secured basin through energy barriers, quantifying their characteristic energy scale and heterogeneity across perturbation directions. Across seven power-grid models, this characterization revealed angle-stability vulnerabilities overlooked when stability is assessed solely by the final synchronization state. It also showed that the two energy-barrier measures characterizing the secured basin exhibit distinct associations with structural connectivity and dynamical parameters. This characterization further offers practical advantages, as energy thresholds derived from state-space perturbations remain effective in distinguishing secured and unsecured outcomes under short-duration power disturbances and can be estimated efficiently by concentrating simulations near the secured-basin boundary. Overall, the secured-basin framework provides a useful basis for distinguishing node-level structural and dynamical influences on transient stability in oscillator networks with synchronization constraints.
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All authors Jaiyong Lee, Daekyung Lee, Seung-Woo Son, Sang Hoon Lee, Mi Jin Lee, Heetae Kim
Adaptation and Self-Organizing Systems · Cross-listed from q-bio.NC
If the brain were so simple: Information-based drivers of intelligence and their interaction through an n-body-inspired framework
Brett J. Kagan, Johnson Zhou, Forough Habibollahi et al. (+1 more)
Theories of how the
brain processes information and returns intelligent outputs are numerous and often difficult to conclusively test. Here, we consider an approach grounded in informatics and algorithmic thermodynamics for how neural systems respond to different patterns of information in different ways, with a focus on the relationship between the information
entropy of a signal and a new proposed quantity we term information enthalpy, which represents the internal resource of structured information within a system available to be used for predictions and other forms of work. To evaluate the capacity of the external signals to increase information enthalpy in the system, we introduce the information enthalpy potential (IEP) as a defined metric. We propose and implement a method for quantifying the amount of potential information enthalpy - the IEP - in a given signal across a range of example signals. We offer a
conjecture of how information enthalpy may be treated by neural systems within a biological framework before showing how it may integrate and offer falsifiability to existing approaches such as the Free Energy Principle. This framework is also positioned in light of the role of neural criticality. Finally, we postulate a testable and falsifiable framework where the distinct mechanisms within each driver interact through a described n-body-inspired model to govern the "motion" of a neural system through a high dimensional state-space. Through these processes, it is proposed that these features form the most fundamental basis of the neural drivers that give rise to the complexity of adaptive behaviors that are commonly called: intelligence.
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All authors Brett J. Kagan, Johnson Zhou, Forough Habibollahi, Valentina Baccetti
Quantum Gases
Universal Drude Weights in One-dimensional Repulsive Fermi Gas
Xiangguo Yin, Dawei Niu, Shuang Zhang et al. (+3 more)
Building on the Bethe ansatz and generalized hydrodynamics, we rigorously establish universal relations between Drude weights governing charge,
spin, and energy transport and thermodynamic properties for the one-dimensional repulsive two-component continuum Fermi gas - the paradigmatic integrable Yang-Gaudin model. We analytically derive thermodynamic expressions for charge Drude weights: $D_{nn}$, $D_{nm}$, $D_{ne}$ (responses of particle, magnetization and energy currents to a chemical potential gradient) equal the particle density, magnetization, and temperature times
entropy density, respectively. These relations constitute a hallmark of ballistic transport, and can be generalized to other 1D continuum integrable systems. Furthermore, we investigate
spin Drude weight ($D_{mm}$, $D_{me}$) at zero and low temperatures. They characterize the magnetization and energy current responses to a
magnetic field gradient, revealing an essential
spin-charge coupling feature in
quantum transport. We find that the Drude weights $D_{nm}$, $D_{mm}$, and $D_{me}$ across the $\mu\text{-}H$ plane remarkably map out the zero-temperature phase boundary. This work fills a critical gap in the understanding of transport within integrable
quantum gases and furnishes a direct theoretical foundation for future ultracold-atom experiments.
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All authors Xiangguo Yin, Dawei Niu, Shuang Zhang, Shizhong Zhang, Yunbo Zhang, Xi-Wen Guan
High Energy Astrophysical Phenomena
Improved analysis of time delays between radio wavelengths and X-ray of Sgr A* flares in the shock oscillation model
Ramiz Aktar, Toru Okuda and Chandra B. Singh
We present an improved analysis of the time delays between
radio and X-ray
flares from the supermassive black hole Sagittarius A* (Sgr A*), extending our previous shock oscillation model by incorporating Compton scattering. Our simulations predict delay times of 1-4 h between X-ray and
radio flares, 20-40 min and 0.5-1 h between 334 GHz and 4.5 $\mu$m and 2-8 keV
flares, and 7-20 min and 0.5-1 h between 22-43 GHz and 350 GHz
radio flares, respectively, in good agreement with recent observations. The delay time between the
radio emissions (synchrotron) and X-ray emissions (bremsstrahlung) is interpreted as the transit time for sound waves traveling from the central core near the event horizon to the location of the oscillating shock. Additionally, the delay time observed between different
radio wavelengths corresponds to the transit time of sound waves moving between the frequency-dependent effective radii $R_{\rm eff}(\nu)$, where the optical thickness $\tau_{\nu}(R)$ at frequency $\nu$ equals one on the surface of the
accretion disc. The X-ray emission and the
radio emission at lower frequencies peak later than the
radio emission at higher frequencies. This delay occurs because the acoustic perturbations created by synchrotron emission peak near the event horizon and then expand outward. Conversely, an inverse delay happens when the acoustic waves generated by the upstream shock wave travel toward the event horizon. The predicted delay times from this interpretation qualitatively match the numerical results obtained in simulations.
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Strongly Correlated Electrons
Probing and Manipulating Quantum Materials with Strong-field Terahertz and Mid-infrared Radiation
S. J. Li, H. Y. Wu, S. J. Zhang et al. (+1 more)
Emergent phenomena in
quantum materials arise from interactions among different degrees of freedom. Identifying these interactions and establishing their roles in ordered states are central problems in condensed-matter physics and provide a basis for controlling material properties. Many relevant low-energy excitations and gaps lie in the terahertz (THz) and mid-infrared (MIR) range, where intense phase-stable fields can both interrogate nonlinear dynamics and drive selected degrees of freedom far from
equilibrium. This review surveys recent progress in probing and manipulating
quantum materials with strong-field THz and MIR radiation, with emphasis on nonlinear electronic dynamics, collective-mode coupling,
symmetry-sensitive responses and field-induced changes in electronic structure and ordered states. Particular
attention is given to developments enabled by the Synergetic Extreme Condition User Facility (SECUF).
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All authors S. J. Li, H. Y. Wu, S. J. Zhang, Y. T. Li
Quantum Physics
Sub-MHz SWAP spectroscopy of two-level systems in superconducting qubits
Joaquin Minguzzi, John Clai Owens, Oskar Painter et al. (+2 more)
An outstanding challenge in superconducting
quantum circuits is mitigating loss from two-level system (TLS) defects. SWAP spectroscopy with flux-tunable
qubits can detect individual TLSs, but the Rabi chevrons that signal coherent exchange have been observed only for the most strongly coupled defects. Here, we introduce a sequence with fast flux pulses only at state preparation and readout, switched off during the energy-relaxation delay for finer frequency resolution and longer interaction times. We detect Rabi chevrons at swap rates as low as 0.1 MHz, an order of magnitude lower than previously reported. In the dressed-state picture, we fit the coherent swap oscillations to extract the TLS energy-relaxation time. These Rabi chevrons reveal coherent TLSs with a median energy-relaxation time of 10 microseconds, at coupling strengths previously associated with incoherent TLSs. The swap coherence times exceed the
qubit T2* limited by flux noise, indicating that the dressed gap protects them from low-frequency 1/f noise.
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All authors Joaquin Minguzzi, John Clai Owens, Oskar Painter, Matthew H. Matheny, Loren J. Swenson
Plasma Physics
The Richtmyer-Meshkov Instability of Thermal, Isotope, and Species Interfaces in a five-moment multi-fluid plasma
K. C. Tapinou, V. Wheatley, D. Bond et al. (+1 more)
The Richtmyer-Meshkov instability (RMI) results from the impulsive acceleration of a density interface where either it or the acceleration is perturbed. Density interfaces may arise due to a change in gas species, isotope, temperature or a combination of these. We computationally investigate the effect of interface type on the
plasma RMI, which is relevant for a range of applications, including inertial confinement fusion. We simulate the
evolution of single-mode perturbed thermal, species and isotope interfaces in an ideal ion-electron
plasma using the multi-fluid
plasma (MFP) model. We find that in the MFP model, the
evolution of different types of interface differ significantly, in contrast to single-fluid models where they behave similarly if the Atwood number is matched. The thermal and species interfaces produce the most severe response to shock acceleration, experiencing the secondary instabilities and enhanced primary mode growth. The isotope interface
evolution is restrained in comparison to the former cases, resembling the response predicted by single-fluid models. The determining factor in the severity of the MFP RMI is the density ratio across the initial interface in the electron fluid, which is unity for an isotope interface. We observe that as the density ratio across the electron interface decreases, so do the magnitudes of the self-generated fields and consequently the severity of the growth amplification. Generally, the
evolution of the RMI with different types of interface becomes more similar as the level of coupling between the ion and electron fluids is increased, characterised by reducing the
plasma non-dimensional skin depth
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All authors K. C. Tapinou, V. Wheatley, D. Bond, Ingo Jahn
High Energy Physics (Phenomenology)
Quantum Magic and the Strong Coupling Constant
Qiaofeng Liu, Ian Low and Zhewei Yin
The three gauge couplings of the Standard Model (SM) can be parameterized as the fine structure constant $\alpha$, the weak mixing angle $\sin^2\theta_w$, and the strong coupling $\alpha_s$. They are fundamental constants whose values remain unexplained. Previously we showed that minimizing magic production in charged-lepton scattering reproduces $\sin^2\theta_w$ with great precision. Here we study magic production in the six flavor-diagonal color-singlet channels $q\bar q\to q\bar q$ at tree level, including
photon, gluon, $W/Z$, and
Higgs exchange. Varying only $\alpha_s$, with all other inputs fixed at each center-of-mass energy, we find that the finite-$\alpha_s$ magic minimum in the top channel reproduces the $\overline{\mathrm{MS}}$ value of $\alpha_s$ to within $5\%$ from $1~$TeV to $10^9~$GeV.
Higgs exchange involving the large top Yukawa coupling is essential for this agreement. All six channels produce near-minimal magic at the SM couplings, and reducing $\alpha_s$ toward $\alpha$ increases their magic production, potentially explaining why the strong interaction is “strong.” To understand why minimizing magic reproduces both $\sin^2\theta_w$ and $\alpha_s$, we
conjecture that the parameters of fundamental interactions among color singlets reflect a principle of
quantum computational efficiency, with the physical universe emerging from a
quantum simulation subject to constrained resources.
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Fluid Dynamics · Cross-listed from cs.LG
Cova-PINN: Cross-Domain Conservation Physics-Informed Neural Network for Fluid-Solid Conjugate Heat Transfer in Complex Geometries
Weizheng Zhang, Xunjie Xie, Hao Pan et al. (+1 more)
Multi-domain physics-informed neural networks (PINNs) flexibly model medium-specific representations to solve fluid–solid conjugate heat transfer (CHT). However, standard multi-domain PINNs enforce governing equations and interface conditions on separately sampled domain supports, which can yield plausible temperature fields but inaccurate end-to-end energy transfer and outlet temperatures. We propose Cova-PINN, a multi-domain PINN framework that aligns conservation support with thermal interaction paths in complex geometries. Cova-PINN jointly optimizes cross-domain composite control-volume balances at the local scale and paired-wall closure at the global exchanger scale. We evaluate Cova-PINN on four triply periodic minimal surface (TPMS) heat exchangers and a geometrically distinct DualMS design against CHT-specific, optimization-oriented, and complex-geometry PINN baselines under a common protocol. Relative to the closest baseline, MUSA-PINN-CHT, Cova-PINN reduces average outlet-temperature and device-level closure errors across the four TPMS
topologies by $37.7\%$ and $60.2\%$, respectively, while also improving full-field and heat-duty accuracy, with consistent gains on DualMS.
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All authors Weizheng Zhang, Xunjie Xie, Hao Pan, Lin Lu
Astrophysics of Galaxies
The Binary Fraction of Milky Way Field Stars in DESI: Dependence on Chemical Abundance
Tian Qiu, Wenting Wang, Sergey E. Koposov et al. (+39 more)
Binary populations encode information about the physical conditions of
star formation and the subsequent
evolution of stellar populations. Adopting a statistical method based on multi-epoch line-of-sight velocity variations, we constrain the binary fraction, $f_b$, of field main-sequence turn-off
stars in the Milky Way using data from the second data release of the DESI Milky Way Survey. $f_b$ is found to primarily increase with lower [Fe/H]. At $[\mathrm{Fe}/\mathrm{H}]\gtrsim -1.3$, $f_b$ shows a modest increase with increasing [Mg/Fe], whereas no clear trend is detected at lower [Fe/H]. The apparent variations of $f_b$ with angular momentum and Galactic height are largely explained by their underlying [Fe/H] distributions, while the remaining variations broadly follow differences in [Mg/Fe]. Within overlapping regions of the [Fe/H]–[Mg/Fe] plane, the thin disk, thick disk, stellar
halo and GSE populations exhibit no significant differences in their binary fractions. Thus, our measurements indicate that the variation in $f_b$ is dominated by chemical abundance, which could be explained by the
metallicity-dependent gas cooling efficiency and fragmentation. The weaker [Mg/Fe] dependence at fixed [Fe/H] might be associated with the formation conditions of
stars, with higher [Mg/Fe]
stars generally forming earlier under a more gas-rich and turbulent environment.
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All authors Tian Qiu, Wenting Wang, Sergey E. Koposov, Songting Li, Nathan Sandford, Ting S. Li, Joan Najita, Jessica Nicole Aguilar, Steven Ahlen, Davide Bianchi, David Brooks, Aurelio Carnero Rosell, Todd Claybaugh, Andrei Cuceu, Axel de la Macorra, Arjun Dey, Peter Doel, Jaime E. Forero-Romero, Enrique Gaztañaga, Satya Gontcho A Gontcho, Gaston Gutierrez, Stephanie Juneau, Robert Kehoe, Martin Landriau, Laurent Le Guillou, Aaron Meisner, Ramon Miquel, Enrique Paillas, Will Percival, Francisco Prada, Ignasi Pérez-Ràfols, Corentin Ravoux, Graziano Rossi, Eusebio Sanchez, Christoph Saulder, Edward Schlafly, David Schlegel, Michael Schubnell, Joseph Harry Silber, Małgorzata Siudek, Gregory Tarlé, Benjamin Alan Weaver
Quantum Physics
A lower bound on the overhead of addressable surgery on sparse stabiliser codes
Nouédyn Baspin
We show that, for stabilisers codes, there always exists a logical subspace requiring $\tilde{\Omega}(k^2)$ ancillary
qubits to be measured with a sparse surgery ancilla. For CSS codes the hard subspace can be taken to be generated by all-X, or all-Z operators. As a result, for codes with large $k$, constant overhead ancillas can only realise a small fraction of possible measurements.
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Nuclear Theory
Production Memory of the $^{225}\mathrm{Ra}$-$^{225}\mathrm{Ac}$ Clock in Neutron-Star Merger Ejecta
Hisham Anwer
Radioactive
nuclei in
neutron-
star merger ejecta carry information about both their abundance and their production history. Using the $^{225}\mathrm{Ra}$-$^{225}\mathrm{Ac}$ sequence, we establish exact conditions linking a surviving isotope partition to the time available for parent decay. An Ac fraction of 0.1 produced solely through Ra decay requires at least 2.456 days, providing a direct consistency test for proposed source states. We show that subsequent activity retains additional production
memory: two histories with the same mean birth time can produce different response crossings. This distinction is captured analytically and separates mean chronology from the influence of the production-time distribution. A controlled radiation calculation then shows how deposition and
photon escape transform the nuclear contrast into a common light-curve pivot for fixed ejecta properties. The results connect nuclear production chronology to late-time merger emission and provide
benchmarks for nucleosynthesis and radiation-transport calculations.
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Quantum Physics
Attainable Boundaries versus Operational Equivalence: Dual Benchmarks for the Hierarchical Assessment of Quantum Resources
Sunho Kim, Chunhe Xiong and Junde Wu
While conventional
quantum resource theories quantify utility relative to an idealized set of free states, practical implementations are confined to a specific supply environment—a framework encompassing all states realizable or preparable via current experimental apparatus and design choices, not limited to free states. This work proposes a novel framework for evaluating the relative utility of arbitrary
quantum states against the resource set made accessible by these current selections. We specifically focus our investigation on two canonical representations: the set of states reachable via free operations as the attainable boundary imposed by current experimental constraints, and the set defined through numerical optimization as the criterion for operational equivalence. Our framework establishes two core evaluation methodologies. First, we provide a strategy-dependent
benchmark by assessing a state's performance relative to the reference set under its individually optimized strategy, thereby quantifying achievable performance. Second, we derive a computable lower bound on this superiority by considering optimal strategies for each state individually, enabling the quantification of strategy-independent relative performance independent of specific experimental setups. Beyond relative efficiency metrics, we demonstrate the practical utility of this approach for resource management scenarios, including the selective extraction of states advantageous for storage and distribution, and the concentration of residual resources. Using
quantum entanglement as a paradigmatic example, we prove that distillable
entanglement can be fully recovered via extraction and concentration when the reference set is restricted to pure states, thereby demonstrating the practical relevance of our framework.
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High Energy Physics (Phenomenology)
Systematic Uncertainties in Ultralight Boson Constraints from Superradiance
P.S. Aswathi and Ling Sun
Ultralight
bosons are well-motivated candidates for physics beyond the Standard Model and may constitute part or all of the dark matter. Black-hole superradiance provides a powerful means of probing these particles through their gravitational interaction with rotating black holes. This mechanism has motivated a growing body of constraints from electromagnetic measurements of black-hole
spins and, more recently, gravitational-wave observations. Gravitational-wave probes draw on several distinct signatures: the
spins of merging binary black holes, gravitational radiation emitted by
boson clouds, and potential imprints of cloud-induced changes to binary dynamics. The interpretation of these probes depends on method-specific astrophysical and theoretical assumptions, including black hole formation, natal
spin, age,
accretion history, population priors, and
boson self-interactions. In this paper, we review the principal electromagnetic and gravitational-wave constraints derived from black-hole superradiance, with particular emphasis on their underlying assumptions and systematic uncertainties. The distinct observational signatures and systematic uncertainties of these approaches offer complementary perspectives on the viability of ultralight-
boson models. In particular, their overlapping coverage around
boson masses of $10^{-13}$-$10^{-12}$ eV makes this region particularly informative for comparing constraints, with
attention to the assumptions underlying each result.
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High Energy Physics (Phenomenology)
Probing CP violation in dark scalar decays at the SHiP experiment
Mayumi Aoki and Takashi Shimomura
We investigate CP violation in the decays of a GeV-scale dark scalar
boson into
mesons,
muons and
photons. Both scalar and pseudoscalar couplings to the SM
fermions are considered to study how the CP structure of the dark scalar
boson can be probed through its decays. The scalar and pseudoscalar interactions predominantly induce decays into two-
meson and three-
meson final states, respectively. We propose the simultaneous observation of these two classes of decay modes as a probe of CP violation in the dark scalar sector. The expected signal rates at the SHiP and FASER2 experiments are evaluated based on the dark scalar production from heavy-
meson decays. We find that the ratio of three-
meson to two-
meson decay events at SHiP has the potential to probe a wide range of the CP-violating parameter space for dark scalar masses around the GeV scale. We also show that the two-
muon and di-
photon channels can provide complementary information for the CP violation search.
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Quantum Physics
Quantum Simulation of a Hyperbolically Driven Quantum System with Superconducting Circuits
Han-xin Che, Yangyang Yu, Tao Zhang et al. (+4 more)
Hyperbolic geometry hosts a plethora of exotic
quantum phenomena ranging from holographic duality to novel topological phases. However, investigating these effects experimentally remains challenging due to the Euclidean constraints of natural crystalline materials. While recent synthetic
lattices have achieved static realizations, they often lack the dynamical tunability required to explore the full
geometric landscape. Here, we overcome these limitations by implementing a
quantum simulation of
hyperbolic geometry within the parameter space of a superconducting
quantum circuit. We construct a Hyperbolically Driven
Quantum System (HDQS) by mapping the
hyperbolic properties onto the dynamically controllable
Hamiltonian parameters. By probing the systems' response under
geometric quantum driving, we elucidate how the intrinsic geometry of the parameter space dictates observable physical quantities. Furthermore, we extend the theoretical framework to realize ensemble simulation. This generalization enables us to harness the fast coherent control of superconducting
qubits to capture essential
geometric characteristics, establishing a versatile platform for exploring
quantum dynamics on
hyperbolic manifolds.
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All authors Han-xin Che, Yangyang Yu, Tao Zhang, Wen Zheng, Hai-Feng Yu, Xinsheng Tan, Yang Yu