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Physics

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Tuesday 28 July

Atomic Physics

Achieving 100$\,$MHz Instantaneous Bandwidth in a Broadband Rydberg Microwave Sensor

Yuhan Yan, Jinyin Wan, Xuejie Li et al. (+6 more)

Rydberg atoms have attracted considerable attention in recent years as a novel platform for microwave sensing, owing to their unique physical merits: large transition dipole moments between Rydberg levels and broad frequency coverage. As a critical figure of merit for Rydberg microwave sensors, instantaneous bandwidth serves as a key benchmark for evaluating their viability in practical applications. Previous studies on instantaneous bandwidth remain limited to single-frequency operation, with typical demonstrated values of only tens of megahertz, a constraint that hampers the real-world deployment of this sensing technology. Here, we experimentally achieve an instantaneous bandwidth of over 100$\,$MHz across a broad frequency range of 2.7-20$\,$GHz and realize a sensitivity in the hundreds of nV$\,$cm$^{-1}\,$Hz$^{-1/2}$ range. The physical mechanism lies in the dressed-state coherence and the interference effect between different transition channels. Our work substantially broadens the instantaneous bandwidth of Rydberg microwave sensors and paves the way for their practical deployment in fields such as radar and wireless communications.
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All authors Yuhan Yan, Jinyin Wan, Xuejie Li, Xing Xia, Haojie Zhao, Binghong Yu, Jianliao Deng, L. Q. Chen, Huadong Cheng

Quantum Physics

The Emergence of Time from Quantum Records: Actualization and the Surprisal Clock

Lionel Martellini

We develop a record-based account of internal time in quantum mechanics. Persistent records first define an ordinal chronology through inclusion of their accumulated Boolean algebras. On a specified record filtration, we prove that, under three minimal consistency requirements, namely dependence only on conditional Born weight, invariance under sequential refinement of the same recorded fact, and continuity, the actualization of each outcome contributes an internal time proportional to its surprisal, defined as the negative logarithm of that probability. A certain outcome therefore contributes no duration, whereas less probable outcomes contribute larger increments. The mean and variance of the accumulated clock are governed by the Shannon entropy and varentropy of the record process, its moment-generating function is related to the R'enyi entropy spectrum, and its pathwise fluctuations admit a Doob decomposition into a predictable entropic compensator and a martingale. Two further results provide independent consistency checks. Within the stated class of finite-dimensional bipartite states, universal additivity of local clock readings across all admissible local record contexts is equivalent to the absence of entanglement. In the quantum Zeno regime, the number of monitoring rounds may diverge while the expected accumulated surprisal tends to zero. The construction therefore supplies a canonical internal-time functional for a specified quantum record process without presupposing an external clock. It does not by itself identify which physical record processes constitute material clocks; determining their production rates and dynamical realization remains a separate problem.
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Quantum Physics

Loss-induced anomalous generalized bunching in multiphoton interference

Rikizo Ikuta

We show that internal loss and survival conditioning can activate anomalous generalized bunching in passive linear optical circuits. We introduce a conditional bunching probability that all photons occupy a target region of accessible output modes, given that all photons survive. For two-photon inputs, we prove that this probability is always monotonic for any circuit size and loss configuration, although a multimode target region can reverse the monotonic direction. For three-photon inputs in a minimal three-mode lossy interferometer, we find a nonmonotonic anomaly in which the conditional bunching probability is maximized for partially distinguishable photons. This behavior is forbidden for the corresponding unconditioned target-region probability, demonstrating that survival-conditioned loss changes the minimal hierarchy of generalized bunching.
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Astrophysics of Galaxies

Interferometric molecular line observations toward the 21 {\mu}m protoplanetary nebula IRAS 06530-0213

Hao-Min Sun, Zhuang Zhang, Jun-Yang Liu et al. (+2 more)

The identification of the $21\,\mu\mathrm{m}$ feature in some protoplanetary nebulae remains a longstanding puzzle, whose interpretation requires characterization of the molecular gas environments of associated sources. Here, we present high-resolution interferometric observations from the Northern Extended Millimeter Array toward the $21\,\mu\mathrm{m}$ protoplanetary nebula IRAS 06530-0213. Multiple molecular transitions of $\mathrm{HC_3N}$, $\mathrm{C_4H}$, and $\mathrm{SiC_2}$ are detected and spatially resolved. We analyze these spectral lines alongside previously reported CO and $^{13}\mathrm{CO}$ emission toward this source. Differing from the extended barrel-like molecular structure traced by CO and $^{13}\mathrm{CO}$, $\mathrm{HC_3N}$ and $\mathrm{C_4H}$ are predominantly concentrated in the inner low-latitude equatorial zones. Reproducing the observed morphology requires $\mathrm{HC_3N}$ to possess a more inwardly concentrated abundance distribution compared with CO and $^{13}\mathrm{CO}$, implying that the inner equatorial regions provide favorable conditions for carbon-chain chemistry.
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All authors Hao-Min Sun, Zhuang Zhang, Jun-Yang Liu, Sheng-Li Qin, Yong Zhang

Optics

Resonance-Induced Sign Reversal of Optical Gradient Forces and Three-Dimensional Singularity Trapping

Jinsheng Lu, Soon Wei Daniel Lim and Federico Capasso

In atomic physics, tuning the light frequency across a resonance reverses the trapping force between bright and dark field regions, yet a unified analytical description of this principle applicable to photonic resonators in general has not been established. Here we show that sweeping the incident wavelength through a resonance in the optical response of the particle or device induces a $\pi$ phase shift, reversing the gradient force from attractive to repulsive. A generalized Fano line-shape model captures this quantitatively across physically distinct resonant systems, from plasmonic nanoparticles to high-Q metasurfaces, with full-wave simulations confirming the predictions in every case. Building on this framework, three-dimensional singularity trapping of silicon nanoparticles is demonstrated using counter-propagating vector beams and metasurfaces, with trapping potential depths competitive with conventional bright-field traps. These results establish a platform-independent design principle for controlling optical forces in resonant systems, with broad implications for optical manipulation, quantum optomechanics, and precision metrology.
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Mathematical Physics

A Rigorous Proof of Metric Blow-Up for Pseudospherical Metrics Associated with the Degasperis–Procesi Equation

Zhenhua Shi and Mingyue Guo

This paper studies finite-time blow-up of pseudospherical metrics induced by solutions of the Cauchy problem for the Degasperis–Procesi equation. For initial momentum profiles satisfying suitable left–right sign conditions, we use the method of characteristics, the momentum-transport formula, the Green's-function representation, and Riccati-type differential inequalities to analyze the metric along a distinguished characteristic. We prove that the associated coframe remains non-degenerate before the critical time, so that the induced pseudospherical metric is well defined in the precritical region. Moreover, as wave breaking is approached, the metric component \(g_{22}\) diverges to \(+\infty\); when \(\mu\neq0\), the mixed component \(g_{12}\) also blows up in absolute value. Thus, finite-time wave breaking for the Degasperis–Procesi equation is shown to induce blow-up of certain components of the corresponding pseudospherical metric.
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Astrophysics of Galaxies

From Starburst to Quenching: Physical Properties of Extremely Compact Starbursts at z$\sim$0.1

Can Xu, Mengyuan Xiao, Min Bao et al. (+5 more)

The compaction phase plays a crucial role in galaxy evolution, as it is strongly linked to star formation activities and structural transformation. We have identified a sample of extremely compact starburst galaxies (eCSBs) at low redshift~(z$\sim$0.1), which represent this critical evolutionary stage. These eCSBs are massive outliers with intense star formation and high infrared luminosities comparable to (U)LIRGs, while their structure already resembles quiescent galaxies. To investigate their molecular gas properties, we conducted IRAM 30m observations of $^{12}$CO J = 1–0 and $^{12}$CO J = 2–1 emission lines. Our results indicate that eCSBs exhibit a notably low molecular gas fraction~($\sim3\%$), and short gas depletion time~($\sim$ 20 Myr), suggesting that these galaxies are rapidly exhausting their remaining gas reservoir. Compared to normal (U)LIRGs, eCSBs show systematically lower $^{12}$CO(2-1)/$^{12}$CO(1-0) ratio~($R_{21} \sim 0.65 \pm 0.06$), similar to main sequence galaxies. The relatively low CO excitation may be associated with their high central stellar mass densities. These findings provide new insight into the molecular gas properties of galaxies during the compaction phase, highlighting their unique condition and rapid evolution toward quiescence.
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All authors Can Xu, Mengyuan Xiao, Min Bao, Qiusheng Gu, Longji Bing, Yong Shi, Yifei Jin, Shiying Lu

Instrumentation and Methods for Astrophysics

LiteBIRD Mission Overview after Mission Reformation

LiteBIRD Collaboration: K. Aizawa, H. Akamatsu, R. Akizawa et al. (+171 more)

LiteBIRD is a JAXA-led space mission designed to produce all-sky microwave polarization maps. Its primary science goal is to test representative inflationary models by measuring the cosmic microwave background $B$-mode polarization generated by primordial gravitational waves, while also providing new insights into cosmology, particle physics, and astrophysics. The mission concept has been updated following the reformation activities initiated after the Mission Definition Review in 2024. The current concept preserves the central scientific objectives, while simplifying the payload configuration: a single telescope covers 12 frequency bands with band centers spanning 40 to 402~GHz, corresponding to an optical coverage of 34–448~GHz. The telescope is a cross-Dragone reflector with a 500~mm aperture diameter, cooled to approximately 5~K and coupled to transition-edge-sensor bolometer arrays operated at 0.1~K. LiteBIRD will observe from a Lissajous orbit around the Sun–Earth L2 point during a nominal 3-year survey. More specifically, the primary scientific objective is to achieve total uncertainty in the tensor-to-scalar ratio of $\delta r < 0.002$ (68% C.L.), including contributions from foreground residuals, statistical uncertainties, instrumental systematics, and margin contingency. The corresponding map-noise requirements are specified separately for the low-, mid-, and high-frequency ranges over the reionization and recombination multipole ranges. This sensitivity makes LiteBIRD unique not only for inflationary science but also for a broad range of scientific investigations probing the history of both the early and late Universe, as well as for astrophysical processes, including Galactic science. This paper summarizes the scientific objectives, updated payload and instrument concepts, observation strategy, and ground segment plans.
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All authors LiteBIRD Collaboration: K. Aizawa, H. Akamatsu, R. Akizawa, E. Allys, A. Anand, D. Audley, J. Aumont, S. Azzoni, C. Baccigalupi, M. Ballardini, A. J. Banday, G. Barbieri Ripamonti, R. B. Barreiro, N. Bartolo, S. Basak, M. Bersanelli, A. Besnard, D. Blinov, F. Bouchet, F. Boulanger, N. Brancadori, T. Brinckmann, E. Calabrese, P. Campeti, A. Carones, F. Carralot, F. J. Casas, J. Chandran, Y. Chinone, M. Citran, F. Columbro, A. Coppolecchia, F. Cuttaia, P. Dal Bo, P. de Bernardis, T. de Haan, E. de la Hoz, M. De Lucia, M. De Petris, S. Della Torre, C. Dickinson, P. Diego-Palazuelos, J. J. Díaz García, T. Dotani, M. Douspis, K. Ebisawa, H. K. Eriksen, J. Errard, E. Ferreira, F. Finelli, C. Franceschet, R. Fujimoto, U. Fuskeland, G. Galloni, M. Galloway, M. Gerbino, M. Gervasi, R. T. Génova-Santos, T. Ghigna, S. Giardiello, E. Gjerløw, M. Gomes, A. Gruppuso, J. E. Gudmundsson, P. Hargrave, S. E. Harper, M. Hasegawa, M. Hazumi, S. Henrot-Versillé, L. T. Hergt, E. Hivon, K. Ichiki, K. Ikuma, T. L. Irikura, H. Ishino, B. Jost, R. Keskitalo, K. Kikuno, K. Kohri, E. Komatsu, L. Lamagna, M. Lattanzi, C. Leloup, M. Lembo, F. Levrier, J. Liu, A. I. Lonappan, M. López-Caniego, G. Luzzi, J. Macias-Perez, A. Maeda, B. Maffei, D. Maino, V. Maranchery, E. Martínez-González, S. Masi, S. Matarrese, F. T. Matsuda, T. Matsumura, S. Micheli, M. Migliaccio, M. Monelli, L. Montier, L. Mousset, S. Myozen, Y. Nagano, R. Nagata, K. Nagayoshi, M. Najafi, T. Namikawa, P. Natoli, F. Noviello, A. Occhiuzzi, K. Odagiri, S. Oguri, H. Ohsaki, S. Okumura, L. Pagano, A. Paiella, D. Paoletti, S. Paradiso, G. Pascual-Cisneros, G. Patanchon, V. Pavlidou, F. Piacentini, M. Piat, G. Piccirilli, M. Pinchera, G. Pisano, G. Polenta, L. Porcelli, F. S. Porter, M. Reinecke, M. Remazeilles, A. Rizzieri, J. A. Rubiño-Martín, M. Ruiz-Granda, Y. Sakurai, L. Salvati, J. Sanghavi, G. Savini, D. Scott, Y. Sekimoto, M. Shiraishi, G. Signorelli, S. Stellati, R. Stompor, R. M. Sullivan, R. Takahashi, R. Takaku, H. Takakura, Y. Takase, A. Tartari, K. Tassis, K. Tateoka, L. Terenzi, M. Tomasi, M. Tristram, M. Tsujimoto, D. Vaccaro, L. Vacher, B. van Tent, P. Vielva, S. Vinzl, K. Watanuki, D. J. Watts, I. K. Wehus, G. Weymann-Despres, B. Winter, E. J. Wollack, N. Y. Yamasaki, K. Yoshihara, A. Zacchei, M. Zannoni

Lattice Field Theory

Normalizing Flows to Reconstruct Pseudo-PDFs

Yamil Cahuana Medrano and Kostas Orginos

We investigate a normalizing-flow approach for reconstructing parton distribution functions (PDFs) from synthetic matrix-element data. Our framework combines Gaussian Process priors with invertible neural networks to learn a posterior distribution over PDFs consistent with limited Ioffe-time data. We demonstrate that the architecture preserves physical constraints and extrapolation properties.
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Optics

Real-Time Megapixel Kilohertz Neuromorphic Shack-Hartmann Wavefront Sensor

Yuhan Bao, Chenxin Shao and Kaiwei Wang

Conventional frame-based Shack–Hartmann wavefront sensors (SHWFS) are limited by dynamic range and the intrinsic trade-off between spatial and temporal resolution, while high-bandwidth acquisition poses additional challenges for real-time wavefront reconstruction. This work presents a real-time, megapixel, kilohertz neuromorphic SHWFS to overcome these limitations. In static optical metrology, the proposed pipeline achieves one-shot wavefront acquisition under extreme illumination non-uniformity, reaching a dynamic range of 260 dB at a 20 Hz acquisition frequency. Owing to this high dynamic range and the concomitant high-intensity resolution, wavefront reconstruction errors in dim and bright sub-apertures are reduced by 59% and 70%, respectively, relative to conventional frame-based SHWFS. For dynamic wavefront sensing, the system provides kilohertz-rate centroid tracking over a megapixel field of view with microsecond-scale latency. Centroid localization errors are 0.18 pixels during optical alignment supervision and 0.26 pixels in high-speed turbulence observation, verifying the accuracy and reliability of the system across dynamic scenarios. The per-sub-aperture processing throughput reaches 420,737 Hz on a standard CPU, demonstrating high-speed real-time computation without specialized hardware acceleration. Together, these results establish a unified neuromorphic SHWFS framework for high-fidelity one-shot static wavefront reconstruction and real-time high-bandwidth dynamic wavefront sensing.
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Disordered Systems and Neural Networks · Cross-listed from cs.AI

Many-body Tipping Dynamics of ChatGPT-like AIs

Frank Yingjie Huo and Neil F. Johnson

Why do ChatGPT-like AIs, despite major architectural and training differences, unexpectedly tip to undesirable content (e.g. harmful, misleading, repetitive) even under deterministic greedy decoding? We show that a broad class of such tippings is caused by the many-body interactions between tokens (spins) as they cross the finite-layer system. Tipping emerges as a dynamical first passage process between competing output basins. Attention disorder controls the transport toward, away from, or along the basins' boundary. A few-basin reduction yields a closed finite-layer threshold, whose coarse-grained predictions show good agreement across ChatGPT-like families. These results suggest that a broad class of AI failures represents 'foreseeable engineering risk' rather than inherently unpredictable behavior, with important implications for legal and societal assessments of AI harm.
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Mathematical Physics · Cross-listed from math.PR

A note on the random constrained-degree percolation model on $\mathbb{L}^2$

Marco Ticse

This note considers a constrained-degree percolation model in a random environment on the square lattice, where each vertex is assigned a random degree constraint, and edges attempt to open at random times. We prove that whenever an infinite open cluster exists, it is almost surely unique, implying the positivity of the connectivity function in the supercritical regime.
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Quantum Gases

Tuning Density and Spin Ordering of Degenerate Fermi Gases in an Optical Cavity

Wei Qin, Yuan-Hong Chen and Renyuan Liao

We investigate a spin-degenerate Fermi gas coupled to a high-finesse optical cavity, where the competition between scalar and vectorial couplings is controlled by the relative polarization angle of the pump and cavity fields. We find that the phase transition threshold is synergistically determined by the scalar-vectorial coupling weight and Pauli blocking, with the latter dictating the critical pump lattice depth required for the onset of superradiance. For a two-component Fermi gas with opposite spins, the population ratio drives two distinct types of phase transitions corresponding to real-space phase separation: continuous and discontinuous. Nevertheless, the boundary of the phase transition remains fundamentally governed by the scalar-vectorial coupling competition. We clarify the impact of the relative polarization angle on phase transitions of the system; these results also apply to bosonic systems. Our results provide valuable theoretical insights for future experimental realizations.
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Nuclear Theory

Bayesian Variational Method for Precision Few-Body Calculations

Shigeyoshi Aoyama

Many variational descriptions of quantum many-body systems rest on an expansion over basis functions, and their practical limit is often set by the number of basis functions required. We propose the Bayesian variational method (BVM), in which the basis functions are selected by Bayesian optimization: a Gaussian-process surrogate model, conditioned on the candidates evaluated so far, predicts which candidates are most likely to lower the energy, and the candidate evaluations, being mutually independent, are distributed over many nodes. Two further ingredients make the method practical. An incremental diagonalization evaluates each candidate by reusing the previous diagonalization of the accepted basis instead of solving the full eigenvalue problem anew. A trimming procedure continually removes basis functions that have become nearly linearly dependent, keeping the accepted basis small while guiding it toward the optimal solution. The BVM applies broadly to energy variational problems based on basis-function expansions in quantum mechanics; here we apply it to the Gaussian expansion method (GEM), a standard approach in few-body physics. Because the GEM basis is nonorthogonal, its linear dependence is strong, so the basis reduction achieved by the BVM is large. The reduction both accelerates the computation and, more importantly, greatly reduces the memory requirement, one of the central bottlenecks of the variational method: the reference energy of the full 32,000-dimensional GEM diagonalization is reproduced to within 0.01 K with only 705 basis functions and to within 0.001 K with 2,127, corresponding to memory reductions of 99.95% and 99.56%, since the matrix storage grows as the square of the basis dimension. Within the GEM, this opens a path to the precision study of six- and seven-body systems, and beyond, that has so far been difficult to reach.
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Optics

Monolithic Multifocal Diamond Metalens for High-Power Laser Systems

Xiaoxuan Li, Xiaoyu Sun, Ce Li et al. (+6 more)

High-power laser systems increasingly rely on multi-beam processing to enhance manufacturing throughput. However, conventional multifocal systems remain constrained by bulky architectures, stringent alignment requirements, and susceptibility to laser-induced degradation under intense irradiation. Here, we demonstrate a monolithic multifocal diamond metalens with a 7.2 mm aperture that maintains exceptional thermal stability and power tolerance. The device employs high-aspect-ratio truncated-cone diamond nanopillars to generate two focal spots separated by 200 {\mu}m at a focal length of 4 mm. Under sustained 25 W pulsed-laser irradiation for 1 h, the diamond metalens exhibits a focal shift of only 25.5 {\mu}m, resulting in a maximum processing-depth variation of 33.2 {\mu}m during 4H silicon carbide (SiC) laser scribing, far below the 319.1 {\mu}m deviation observed for a commercial objective lens combined with a beam-splitting diffractive optical element (DOE). Even under extreme optical loading, the metalens withstands continuous-wave laser irradiation up to 8.25 kW for 30 s without structural degradation, while complementary pulsed testing yields a laser-induced damage threshold (LIDT) of 2.45 J/(cm^2) for diamond. This work broadens the operating envelope of transmissive meta-optics to extreme optical loads, opening new opportunities across high-power photonic systems.
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All authors Xiaoxuan Li, Xiaoyu Sun, Ce Li, Zhiqiang Xie, Fengjiang Liu, Boqu Chen, Ding Zhao, Kaikai Du, Min Qiu

Disordered Systems and Neural Networks

Low-Temperature Magnetoresistance Hysteresis in Granular Cr1-xFexO2: Slow Relaxation of Transport-Active Magnetic Configurations

E. Yu. Beliayev, V. A. Horielyi, I. G. Mirzoiev et al. (+1 more)

Low-temperature magnetoresistance loops of compacted CrO2 powders become strongly nonmonotonic when electrical transport is dominated by a small number of spin-dependent intergranular tunnelling paths. We reanalyse previously reported data for undoped CrO2 and Fe-containing Cr1-xFexO2, focusing on additional branch crossings beyond the conventional low-field hysteresis. In the Fe-containing specimen, the resistance decreases, passes through a minimum, rises over an extended field interval, and then decreases again at higher field. This nonmonotonic hysteretic feature is strongly reduced when the magnetic-field sweep is slowed. Digitization of the three fastest sweeps shows that the field at which the resistance starts to recover shifts approximately linearly with sweep rate, corresponding to an effective magnetotransport relaxation time of about 3 s. This scale is attributed not to microscopic spin flips but to the slow evolution of local moment and domain configurations at the intergranular contacts dominating the current. The observations are consistent with conventional negative tunnelling magnetoresistance superimposed on a slower resistance-increasing contribution associated with transient local magnetic disorder. Fe increases coercivity and interfacial magnetic heterogeneity while reducing the overall negative magnetoresistance. The results support a transport-weighted magnetic-reconfiguration mechanism for the unusual hysteresis shape.
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All authors E. Yu. Beliayev, V. A. Horielyi, I. G. Mirzoiev, V. V. Andrievskii

High Energy Astrophysical Phenomena

Tightening Bounds on Warm Dark Matter with High-Redshift Gamma-Ray Bursts

Jun-Jie Wei, Jing-Meng Hao, Ding-Fang Hu et al. (+4 more)

The cold dark matter paradigm successfully explains large-scale structure but faces persistent tensions on small scales. Warm dark matter (WDM) with $\mathrm{keV}$-scale particles can alleviate these issues by suppressing small-scale structure formation. The presence of collapsed structures at high redshifts places strong lower limits on the WDM particle mass $m_x$. Gamma-ray bursts (GRBs) are ideal high-redshift probes due to their extreme brightness. Using the most recent Swift GRB data accumulated over the past two decades, we derive robust constraints on $m_x$ by conservatively assuming that the comoving GRB formation rate is proportional to the cosmic star formation rate (SFR), with an additional redshift evolution parameterized as $(1+z)^\alpha$. Applying a maximum-likelihood analysis to 118 GRBs with redshift $z<10$ and luminosity $L\ge 4.0\times10^{52}\,\mathrm{erg\,s^{-1}}$, we obtain $m_x \gtrsim 1.23\,\mathrm{keV}$ and $\alpha=1.57^{+1.14}_{-0.57}$ at the 95% confidence level (CL). The no-evolution scenario ($\alpha=0$), in which the GRB rate exactly traces the SFR without additional redshift evolution, is excluded at the $5\sigma$ level. Adopting the best-fit value $\alpha=1.57$ as a prior tightens the lower limit on $m_x$ to $m_x \gtrsim 1.59\,\mathrm{keV}$ at the 95% CL. These robust constraints demonstrate that GRBs are a powerful probe of the early Universe. A better understanding of the relationship between the GRB rate and the SFR would enable even tighter limits on WDM models.
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All authors Jun-Jie Wei, Jing-Meng Hao, Ding-Fang Hu, Yang Liu, Bao Wang, Xi Kang, Xue-Feng Wu

Earth and Planetary Astrophysics

KMT-2025-BLG-0975Lb and KMT-2025-BLG-1160Lb: Two Uranus-Mass Planets Beyond the Snow Line Discovered by Microlensing

Cheongho Han, Chung-Uk Lee, Andrzej Udalski et al. (+27 more)

We present the analysis of two planetary microlensing events, KMT-2025-BLG-0975 and KMT-2025-BLG-1160, discovered during the 2025 Galactic bulge microlensing season through high-cadence survey observations. In both events, short-duration anomalies near the peaks of the lensing light curves reveal the presence of planetary companions. Light-curve modeling yields planet-to-host mass ratios of $q = 8.6 \times 10^{-4}$ for KMT-2025-BLG-0975 and $1.3 \times 10^{-4}$ for KMT-2025-BLG-1160. For KMT-2025-BLG-0975, finite-source effects are detected, enabling a measurement of the angular Einstein radius, whereas only a lower limit on this quantity is obtained for KMT-2025-BLG-1160. We estimate the physical parameters of the lens systems through Bayesian analyses constrained by the measured microlensing observables. The results indicate that the planetary companions have masses of $M_{\rm p}=29.8^{+50.5}_{-16.0}~M_\oplus$ for KMT-2025-BLG-0975Lb and $25.4^{+15.5}_{-14.1}~M_\oplus$ for KMT-2025-BLG-1160Lb. Both planets have masses comparable to that of Uranus. The host stars are inferred to be a low-mass M dwarf with a mass of $M_{\rm h}=0.10^{+0.18}_{-0.06}~M_\odot$ for KMT-2025-BLG-0975L and a late K dwarf with a mass of $M_{\rm h}=0.58^{+0.35}_{-0.32}~M_\odot$ for KMT-2025-BLG-1160L. The projected planet–host separations are $a_\perp=0.81^{+0.10}_{-0.11}$~au for KMT-2025-BLG-0975Lb and $a_\perp=2.56^{+0.48}_{-0.71}$~au and $3.29^{+0.61}_{-0.92}$~au for the inner and wide solutions, respectively, of KMT-2025-BLG-1160Lb. In both systems, the planets are located beyond the expected snow-line distances of their hosts, placing them in the cold ice-giant regime.
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All authors Cheongho Han, Chung-Uk Lee, Andrzej Udalski, Andrew Gould, Michael D. Albrow, Sun-Ju Chung, Youn Kil Jung, Kyu-Ha Hwang, Yoon-Hyun Ryu, Yossi Shvartzvald, In-Gu Shin, Jennifer C. Yee, Weicheng Zang, Hongjing Yang, Doeon Kim, Dong-Jin Kim, Byeong-Gon Park, Richard W. Pogge, Przemek Mróz, Michał K. Szymański, Jan Skowron, Radosław Poleskim Igor Soszyński, Paweł Pietrukowicz, Szymon Kozłowski, Krzysztof A. Rybicki, Patryk Iwanek, Krzysztof Ulaczyk, Marcin Wrona, Mariusz Gromadzki, Mateusz J. Mróz

Mesoscale and Nanoscale Physics

Anomalous entanglement scaling from eigenvector nonorthogonality in critical non-Hermitian free fermions

Zhenyu Xiao and Shinsei Ryu

Entanglement carries universal content that labels phases and critical points. We study the entanglement entropy of the steady states of critical non-Hermitian free-fermion chains. It scales logarithmically with subsystem size, but the coefficients vary continuously with the parameters and form a Rényi family that no single central charge can reproduce. We trace this anomaly to an “imaginary” Dirac point, a crossing in the imaginary part of the energy where the occupied state switches between two Bloch states. Their nonorthogonality weakens the occupation discontinuity and lowers the logarithmic coefficient. A low-energy expansion yields closed-form coefficients in excellent agreement with lattice numerics in various one-dimensional critical steady states. Remarkably, weak real onsite disorder leaves this logarithmic scaling intact and enhances the entanglement. Our results provide a generic understanding of entanglement in critical non-Hermitian free-fermion steady states.
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Fluid Dynamics

On the scaling of bubble interactions in dynamic turbulence: theoretical, numerical, and experimental study

Vivek Kumar, Prasoon Suchandra, Shivam Prajapati et al. (+2 more)

This study investigates dilute bubbly decaying homogeneous isotropic turbulence at high Reynolds number using theory, direct numerical simulation, and experiments. The turbulent kinetic energy and dissipation rate follow power-law decay, while the bubble population reorganizes relative to the evolving Hinze scale. When the dissipation decays sufficiently rapidly, the Hinze scale grows faster than the characteristic bubble diameter, driving the population from super-Hinze toward sub-Hinze sizes. The system passes through a mixed regime in which coalescence dominates but breakup remains active, followed by a pure-coalescence regime. Residual breakup in the mixed regime increases the number of small bubbles and enhances coalescence, leading to faster growth of the characteristic bubble size. DNS of dilute bubble-laden turbulence shows decay exponents close to single-phase turbulence and a bubble-size distribution that shifts toward smaller diameter relative to the Hinze scale. Before the transition, the distribution exhibits two power-law ranges associated with capillary effects and inertial breakup; after the transition, it approaches a single capillary-dominated scaling. Theory and DNS predict distinct growth laws for bubble diameter in the mixed and pure-coalescence regimes, together with corresponding scalings for number density, interfacial area, and coalescence rate. These predictions are further assessed in a spatially developing pump-driven bubbly duct flow at higher Reynolds number. Despite confinement, inhomogeneity, and wall production, the measured trends agree with the theoretical and DNS-based scalings. The results identify Hinze-scale drift as the organizing mechanism for bubble interactions in both idealized and practical decaying turbulent flows, and provide guidance for population-balance and interfacial-area-transport models.
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All authors Vivek Kumar, Prasoon Suchandra, Shivam Prajapati, Suhas S. Jain, Cyrus K. Aidun

Chemical Physics

Structured High-Angular-Momentum Coulomb Tensors from Real and Complex Solid-Harmonic Integral Engines: A Perspective

Bo Peng

Electron-repulsion integrals describe the Coulomb interaction between charge distributions built from orbital basis functions. Most integral algorithms generate these quantities through Cartesian Gaussian functions, whose angular shapes are written as powers of $x$, $y$, and $z$, and then transform the result to spherical functions. This route is effective, but from $d$ shells onward the Cartesian representation contains more functions than the spherical space required by the calculation. Direct real or complex solid-harmonic engines work in that target space from the beginning. They therefore produce a smaller final Coulomb tensor while preserving the ordering, phase, and magnetic-quantum-number labels that describe its angular structure. Following this structure beyond integral evaluation reveals direct connections to the algorithms that use the tensor. Simple analytical counts quantify tensor size, angular blocks, radial Slater–Condon parameters, and pair-space work. These quantities guide low-rank factorization, local Hamiltonian construction, quantum simulation, and transformations to spinor or effective-model bases. In this way, solid-harmonic integral engines provide a direct bridge between efficient integral generation and structured many-electron computation.
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High Energy Physics (Phenomenology)

Isolating Scheme Dependence of Quasi-PDFs in the RI/MOM Scheme

Junegone Chay

Quasi-parton distribution functions provide a framework for relating lightcone parton distributions to correlation functions in Euclidean lattice QCD. Their connection to lightcone distributions is established through perturbative matching, whose form depends on the renormalization prescription adopted for the quasi-PDF. In the ordinary RI/MOM scheme, the off-shell reference momentum enters both the renormalized quasi-PDF and the matching coefficient. We propose modified finite renormalization schemes in which neither quantity depends on the RI/MOM reference momentum. Starting from the ordinary RI/MOM scheme, we identify the part to be retained in the renormalized quasi-PDF and include the remaining finite part in the counterterm. We consider a minimal RI/MOM scheme and a modified minimal scheme as specific examples. We derive the corresponding one-loop renormalized quasi-PDFs, counterterms, matching coefficients, and renormalization-group equations, and show explicitly that the finite transformation removes the dependence on the RI/MOM reference momentum from both the renormalized quasi-PDF and the counterterm in the modified schemes.
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Chaotic Dynamics · Cross-listed from math.DS

Grazing bifurcations of linear impact oscillators in the zero damping limit

Olivia J. Goodman and David J.W. Simpson

We consider a harmonically forced linear impact oscillator, where impact events are instantaneous with energy loss. We study the dynamics at the grazing bifurcation of the non-impacting periodic solution in the limit that the damping coefficient of the oscillator is zero. Through numerical computations we show that a recurring sequence of bifurcations exists between points of resonance. Specifically, resonance creates a stable periodic solution that subsequently loses stability in a secondary grazing bifurcation, then regains stability in a saddle-node bifurcation, then transitions to a chaotic attractor through a period-doubling cascade. The dynamics persist under mild parameter variation, so apply to weakly-damped impact oscillators near grazing.
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High Energy Physics (Theory)

The quantum electrodynamics for dyons

D.O.R. Azevedo, O.M. Del Cima, T.S. Dias et al. (+1 more)

The quantum electrodynamics for massive fermions carrying electric and magnetic charges, the dyons, is proposed based on the 1960's seminal works by Cabibbo, Ferrari, and Salam, with the gauge group being $U(1)\times U(1)$, which is associated to a vector field (photon) and a pseudo-vector field (metaphoton), wherein the Dirac quantization is set aside. At the tree level the spectrum consistency of the model is analyzed, and all continuous and discrete symmetries are established. The quantum analysis is performed by using the Becchi-Rouet-Stora (BRS) algebraic renormalization method, which is independent on any regularization scheme. Moreover, thanks to the presence of massless gauge fields, the Lowenstein-Zimmermann (LZ) subtraction scheme is required within the framework of the Bogoliubov-Parasiuk-Hepp-Zimmermann-Lowenstein (BPHZL) renormalization procedure. Finally, it is verified that the proposed model, the dyon quantum electrodynamics (dQED), is free from any anomaly and is multiplicative renormalizable at all orders in perturbation theory, proving, therefore, its quantum consistency.
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All authors D.O.R. Azevedo, O.M. Del Cima, T.S. Dias, E.D. Pereira

Data Analysis and Statistics

Visibility graph-based characterization of extreme values in time series

Juliane T. Moraes, Lucas Lacasa and Cristina Masoller

Complex dynamical systems often display extreme fluctuations of an observed variable that constitute significant deviations from the long-term average, and which are often associated with severe impacts on the system. By definition, extreme events are therefore usually explored from time series recordings. In this work, we characterize extreme values in time series using visibility graphs, a method that non-parametrically maps a time series onto a network, whose topological structure is known to inherit important characteristics of the original time series dynamics. Unlike threshold-based approaches, extreme values in this framework can be identified without the need to introduce external parameters and can be applied to time series generated by both stationary and nonstationary processes. For stationary processes, we exploit a known property of visibility graphs in which the degree of a node is monotonically and nonlinearly related to the corresponding data value. This nonlinear amplification enhances the contribution of large values while suppressing noise, while the monotonic relationship enables a direct ranking of data points according to node degree. This procedure identifies global extreme values and locally prominent ones. For nonstationary processes, the degree ranking in the visibility graph still provides a robust indicator of relative importance. We validate our findings with synthetic time series and with real climatological data. Our results show that extreme-value characterization in stationary time series is enhanced when combining standard methods with visibility-graph-based detection, whereas for nonstationary data, where conventional approaches are often ill-posed, visibility graphs provide an effective alternative. We discuss how sub-sampling the time series using only peak values preserves the ability to identify extreme values while reducing computational cost.
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Strongly Correlated Electrons

Stacking-dependent anisotropic altermagnetism in V$_{1/3}$NbS$_2$

Chris J. Lygouras, Nathan Prouse, Jack H. Drouin et al. (+14 more)

We report profound impacts of the stacking sequence of triangular lattices of magnetic transition metal ions intercalated between the layers of the van der Waals material NbS$_2$. Using single crystal x-ray and neutron diffraction, and transport and magnetization measurements, we show there are two distinct polytypes of $\rm V_{1/3}NbS_2$ with disparate easy axes of magnetization and different anomalous Hall responses. Self-consistent analysis of inelastic neutron scattering data provides evidence for oscillatory RKKY interactions that extend to 1 nm and stabilize quasi-collinear A-type altermagnetic orders in both polytypes though with perpendicular easy axes. The detailed stacking sequence of a bulk polytype crystal dramatically impact its macroscopic anomalous Hall response and magnetism, which suggests a new path to engineer the bulk properties of a layered three dimensional solid.
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All authors Chris J. Lygouras, Nathan Prouse, Jack H. Drouin, Youzhe Chen, Laura Garcia-Gassull, Zili Feng, Mingxuan Fu, Lü Fang, Alexander I. Kolesnikov, Christina Hoffman, Yiqing Hao, Huibo Cao, Maxime A. Siegler, Robert J. Birgeneau, Roser Valentí, Satoru Nakatsuji, Collin L. Broholm

Mesoscale and Nanoscale Physics

Everything is a Spin: The Secret Lives of SU(2)

Avik W Ghosh

Spin, pseudospin, valley, polarization, and other two-component degrees of freedom share the geometry of SU(2), yet their topological manifestations are usually discussed as separate phenomena. This review develops a common geometric language for their winding in momentum and real space,beginning with Berry phase and the Dirac Hamiltonian and extending to graphene, topological insulators, Weyl semimetals, and magnetic skyrmions. We argue that the common thread is not merely topology itself, but the continuity constraints imposed on two-component wavefunctions. Whenever the relevant symmetry is preserved, winding determines which states can continuously connect across an interface or deformation, thereby governing transmission, torque generation, optical selection rules, and other physical responses. We then ask a practical question: what does topology buy an engineer? In skyrmions, winding partitions magnetic configuration space and stabilizes ultrasmall information carriers with tunable dynamics. In graphene, pseudospin matching governs Klein tunneling, enabling a gate-controlled transmission gap without sacrificing the massless Dirac dispersion. In topological insulators and Weyl semimetals, spin-momentum locking and Berry-curvature engineering generate electrically selectable spin currents, while helicity-dependent optical transitions produce circular photogalvanic responses. Together, these examples suggest that topology is not merely a classification of quantum matter, but a design language in which symmetry-protected wavefunction continuity can be engineered for memory, switching, actuation, and sensing.
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General Relativity and Quantum Cosmology

GSpyNetTree-O4: an event validation tool used in the fourth LIGO-Virgo-KAGRA observing run

Sofia Alvarez-Lopez, Man Leong Chan, Franz S. Herbst et al. (+7 more)

The frequent presence of non-Gaussian transient noise, or glitches, in gravitational-wave detector data can affect gravitational-wave searches, parameter estimation, and downstream analyses. To identify and mitigate transient noise near gravitational-wave candidates in a timely manner, the LIGO-Virgo-KAGRA Collaboration employs the Data Quality Report. In the fourth observing run, GSpyNetTree-O4 was deployed within this framework as a tool for glitch classification and event validation. We describe GSpyNetTree-O4 and the main developments relative to its predecessor, GSpyNetTree. The most important update was a new architecture that allowed the simultaneous identification of glitches and gravitational-wave signals when both were present in the same input. We also expanded and augmented the training set with examples in which simulated gravitational-wave signals overlapped with real glitches, and applied $60\,\mathrm{Hz}$ calibration corrections to better match the data expected during the fourth observing run. On test data, the low-mass, high-mass, and extremely high-mass classifiers identified $97.9\%$, $97.7\%$, and $95.4\%$ of glitches, respectively. Among samples without a glitch, including gravitational-wave-only and No Glitch samples, the classifiers correctly reported no data-quality issues in $97.1\%$, $96.6\%$, and $96.0\%$ of cases, respectively. We further assessed the robustness of GSpyNetTree-O4 on unseen glitch morphologies, a small set of Virgo glitches from the fourth observing run, and different choices of the $Q$-value used to construct the time-frequency inputs. GSpyNetTree-O4 was successfully deployed as a Data Quality Report tool and increased automation in gravitational-wave event validation workflows.
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All authors Sofia Alvarez-Lopez, Man Leong Chan, Franz S. Herbst, Dhatri Raghunathan, Airene Ahuja, Annudesh Liyanage, Julian Ding, Alejandro Garcia-Varela, Raymond Ng, Jess McIver

Mathematical Physics · Cross-listed from math.AP

Homogenization of Time-Discrete Gradient Flows

Yunhong Deng, Yuan Gao and Li Wang

In this work, we study the homogenization limit for Fokker–Planck equations on the flat torus with rapidly oscillating diffusion coefficients at the time-discrete level. We discretize the equation in time using a minimizing movement scheme and compare two choices of metric: a transport-type metric and a weighted L2 metric. We prove that this choice is crucial: the two schemes lead to different homogenization limits as the scaling parameter tends to zero, and consequently to different evolution equations as the time step is sent to zero. In particular, only the scheme based on the weighted L2 metric recovers the correct effective dynamics.
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High Energy Physics (Theory)

Monodromy, Hidden Conformal Symmetry and Entropy Product Formula For Kerr-MOG Black Hole

Parthapratim Pradhan

We examine the two-dimensional conformal field theory (2D CFT) dual of the four-dimensional Kerr-MOG (Kerr-modified gravity) black hole using the black hole thermodynamics and monodromy techniques. From these independent procedures, we derive consistent expressions for the left- and right-moving temperatures and the central charge of the dual CFT. Finally, we derive the entropy product using these approaches. We show that the product is not universal as well as not quantized. We further explore the hidden conformal symmetry of the non-extremal Kerr-MOG black hole by analyzing the near-region dynamics of a massless scalar field. The resulting Kerr-MOG/CFT correspondence identifies the near-region geometry with a two-dimensional CFT characterized by the temperatures ($T_{L}, T_{R}$) derived in~(\ref{temperatures}). Moreover, using the Cardy formula, we reproduce the microscopic entropy of the dual CFT and find exact agreement with the Bekenstein-Hawking entropy of the Kerr-MOG black hole. We also show that the low-frequency scalar absorption cross section~(greybody factor) in the near-region Kerr-MOG geometry precisely matches the finite-temperature absorption cross section of the dual 2D CFT. In addition, the near-region scalar wave equation exhibits a hidden $(SL(2,\mathbb{R})_L \times SL(2,\mathbb{R})_R)$ conformal symmetry. These independent results provide strong evidence for the existence of a Kerr/CFT-type holographic duality for the Kerr-MOG black hole, establishing a consistent correspondence between the four-dimensional Kerr-MOG spacetime and a two-dimensional conformal field theory. horizon.
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