History and Philosophy of Physics · Cross-listed from quant-ph
Quantum model for black holes and clocks
Alessandro Coppo, Nicola Pranzini and Paola Verrucchi
We consider a stationary
quantum system consisting of two non-interacting yet entangled subsystems, $\Xi$ and $\Gamma$. We identify a
quantum theory characterizing $\Xi$ such that, in the
quantum-to-classical crossover of the composite system, $\Gamma$ behaves as a test particle within the gravitational field of a Schwarzschild Black Hole (SBH) near its event horizon. We then show that this same
quantum theory naturally provides a representation of $\Xi$ in terms of bosonic modes, whose features match those of the Hawking radiation; this facilitates the establishment of precise relations between the phenomenological parameters of the SBH and the microscopic details of the
quantum model for $\Xi$. Finally, we recognize that the conditions used to characterize $\Gamma$ and $\Xi$ coincide with those required by the Page and Wootters mechanism for identifying an evolving system and an associated clock. This leads us to discuss how the
quantum model for $\Xi$ endows the SBH with all the characteristics of a "perfect" clock.
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Optics · Cross-listed from eess.SP
PIDT: Physics-Informed Digital Twin for Optical Fiber Parameter Estimation
Zicong Jiang, Magnus Karlsson, Erik Agrell et al. (+1 more)
We propose physics-informed digital twin (PIDT): a fiber parameter estimation approach that combines a parameterized split-step method with a physics-informed loss. PIDT improves accuracy and convergence speed with lower complexity compared to previous neural operators.
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All authors Zicong Jiang, Magnus Karlsson, Erik Agrell, Christian Häger
Physics and Society
Extending the Biswas–Chatterjee–Sen model with nonconformists and inflexibles
Amit Pradhan, Parongama Sen and Krzysztof Malarz
Originally, the Biswas–Chatterjee–Sen model was shown to exhibit an order/disorder phase transition for a sufficiently large number of negative interactions among actors. In this paper, the model is extended by the existence of anticonformists and inflexibles. Anticonformists are actors who define themselves in opposition to the group and may intentionally reject what most people accept, while inflexibles are those who do not change their opinions at all. Both discrete and continuous opinions are considered. With direct Monte Carlo simulations and mean-field calculations, we check the influence of fractions of anticonformists and inflexibles on the mean opinion in the system. With the mean-field calculations, we identify ranges of fractions of anticonformists where an ordered phase of the system is available. The results of the mean-field calculations perfectly match the results of the Monte Carlo simulations. We consider inflexibles adhered: (i) to extreme opinions; (ii) to specific opinions, and (iii) chosen independently of their initial opinion. For inflexibles adhered to specific and extreme opinions, they play a role of an effective bias suppressing the disordered phase in the system. The qualitative results of introducing anticonformists (inflexibles) in various ways (discrete/continuous opinions and annealed/quenched disorder) are roughly the same. However, for the model extended by inflexibles, we can observe a systematic shift of the mean order parameter to its higher values for quenched disorder compared with annealed disorder. On the other hand, for anticonformists modeled with a continuous space of opinions, we can observe a systematic shift of the mean order parameter to its higher values compared with the discrete space of opinions.
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Chemical Physics · Cross-listed from cond-mat.soft
Janus Polymeric Giant Vesicles on Demand: A Predictive Phase Separation Approach for Efficient Formation
Eloise Equy, Emmanuel Ibarboure, Eric Grelet et al. (+1 more)
Janus particles, with their intrinsic asymmetry, are attracting major interest in various applications, including emulsion stabilization, micro/nanomotors, imaging, and drug delivery. In this context, Janus polymersomes are particularly attractive for synthetic
cell development and drug delivery systems. While they can be achieved by inducing a phase separation within their membrane, their fabrication method remains largely empirical. Here, we propose a rational approach, using Flory-Huggins theory, to predict the self-assembly of amphiphilic block copolymers into asymmetric Janus polymersomes. Our predictions are experimentally validated by forming highly stable Janus
giant unilamellar vesicles (JGUVs) with a remarkable yield exceeding 90% obtained from electroformation of various biocompatible block copolymers. We also present a general phase diagram correlating mixing energy with polymersome morphology, offering a valuable tool for JGUV design. These polymersomes can be extruded to achieve quasi-monodisperse vesicles while maintaining their Janus-like morphology, paving the way for their asymmetric functionalization and use as active carriers.
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All authors Eloise Equy, Emmanuel Ibarboure, Eric Grelet, Sebastien Lecommandoux
Instrumentation and Detectors
The design and expected performance of the ALICE ITS3 upgrade
Jory Sonneveld
During the LHC Long Shutdown 3 (2026-29) ALICE will replace its three innermost tracking layers by a new detector, the "ITS3". It will be based on newly developed, wafer-scale monolithic active pixel sensors, which are bent into truly cylindrical layers and held in place by light mechanics made from carbon foam. Unprecedented low values of material budget (0.09% $X_0$ per layer) and proximity to the interaction point (19 mm) lead to a factor two improvement in pointing resolutions for particles from very low $p_{\mathrm{T}}$ (O(100 MeV/$c$)), achieving, for example, 20 $\mu$m and 15 $\mu$m in the transversal and longitudinal directions, respectively, for 1 GeV/$c$ particles. After a successful R&D phase (2019-2023), which demonstrated the feasibility of this innovative detector and led to the Technical Design Report (https://cds.cern.ch/record/2890181/), the final sensor and mechanics are being developed right now. This contribution will review the conceptual design and the main R&D achievements, as well as the current activities and road to completion and installation. It includes a projection of the improved physics performance, in particular for heavy-
flavor mesons and
baryons, as well as for thermal dielectrons that will come into reach with this new detector installed.
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Geophysics
Universal scaling between precursory duration and event size across mechanically driven geohazards
Qinghua Lei and Didier Sornette
Many catastrophic events, including landslides, rockbursts, glacier breakoffs, and volcanic eruptions, are preceded by an observable acceleration phase that offers a critical window for early warning and hazard mitigation; however, the duration of this precursory phase remains poorly constrained across sites, scales, and hazard types. This limitation arises because the onset of acceleration is often identified using heuristic thresholds or empirical criteria. Here, we introduce a physics-based framework that objectively constrains the precursory duration from accelerating dynamics, without prescribing the onset a priori or being tied to any specific observable. We analyze a global
dataset of 109 geohazard events across seven continents over the past century, quantifying their precursory durations in a consistent manner. For mechanically driven instabilities, we identify a robust scaling between precursory duration and failure volume spanning more than ten orders of magnitude. When expressed in terms of a characteristic system size, this relationship is close to linear, consistent with finite-size scaling near a dynamical critical point. This behavior indicates that precursory duration reflects the progressive growth of correlated deformation up to system-spanning scales, rather than local rupture kinetics. The resulting universality points to common organizing mechanisms governing the approach to catastrophic failure across mechanically driven geohazards.
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Fluid Dynamics
Effect of directionality on extreme wave formation during nonlinear shoaling
Jie Zhang, Yuxiang Ma, Jiawen Sun et al. (+3 more)
Recent studies have shown that, in coastal waters where water depth decreases significantly due to rapid bathymetric changes, the non-
equilibrium dynamics (NED) substantially increases the occurrence probability of extreme (rogue) waves. Nevertheless, research on depth-induced NED has been predominantly confined to unidirectional irregular waves, while the role of directionality remains largely unexplored. The scarce studies on multidirectional waves mainly rely on numerical simulations and have yielded conflicting results. In this work, we report on an experimental investigation of wave directionality on the depth-induced non-
equilibrium wave statistics. High-order statistical moments, skewness and kurtosis, are used as proxies for the non-
equilibrium wave response. Our results indicate that the directional spreading has a minor effect on decreasing the maximum values of these statistical moments. In contrast, the incidence direction plays a significant role in the non-
equilibrium wave response, which is attributed to the effective bottom slope.
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All authors Jie Zhang, Yuxiang Ma, Jiawen Sun, Limin Huang, Michel Benoit, Saulo Mendes
Plasma Physics
Control of Electron Energy Distribution Functions by Current Waveform Tailoring in Inductively Coupled Radio Frequency Plasmas
Zhaoyu Chen, Zili Chen, Yu Wang et al. (+6 more)
Based on two-dimensional particle-in-
cell simulations a novel approach towards Electron Energy Probability Function (EEPF) and
plasma chemistry control by Current Waveform Tailoring (CWT) in the coil of inductively coupled discharges is proposed. Varying the shape of this current waveform provides electrical control of the dynamics of the electric field in the
plasma. Using sawtooth instead of sinusoidal waveforms allows breaking and controlling the temporal
symmetry of the electric field dynamics. In this way CWT allows controlling the EEPF, the ionization-to-excitation rate ratio, and the
plasma chemistry.
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All authors Zhaoyu Chen, Zili Chen, Yu Wang, Jonas Giesekus, Wei Jiang, Yonghua Ding, Donghui Xia, Ya Zhang, Julian Schulze
Optics
Intraresonance frequency combs in Kerr microresonators
Andrei N. Danilin, Timur R. Yunusov, Ekaterina S. Vahnitskaya et al. (+7 more)
For more than 20 years, optical microresonators have served as the backbone of integrated nonlinear photonics, exploiting Kerr nonlinearity to generate octave-spanning frequency combs, enable
quantum effects, and drive optical parametric oscillators. Since the inception of microresonator-based nonlinear optics, related studies have focused primarily on regimes in which
photons with distinct resonant modes can interact. Although multiple comb lines can occupy a single resonance during the Kerr comb formation process, their mutual interactions have remained largely unexplored. Here we demonstrate a Kerr comb formation that is confined to a single resonance of a microresonator via dual-pumping. MHz-scale comb-line spacing reveals previously unobserved Kerr-comb dynamics, featuring parametrically driven phase multistability that can be observed directly in the temporal domain. Two
laser pumps serve as phase-coupled references for heterodyne read-out, simplifying the measurements.
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All authors Andrei N. Danilin, Timur R. Yunusov, Ekaterina S. Vahnitskaya, Alexey P. Dushanin, Sanli Huang, Zhenyuan Shang, Junqiu Liu, Anatoly V. Masalov, Dmitry A. Chermoshentsev, Igor A. Bilenko
Applied Physics · Cross-listed from cond-mat.soft
Magnetically Driven Elastic Microswimmers: Exploiting Hysteretic Collapse for Autonomous Propulsion and Independent Control
Theo Lequy and Andreas M. Menzel
When swimming at low Reynolds numbers, inertial effects are negligible and reciprocal movements cannot induce net motion. Instead,
symmetry breaking is necessary to achieve net propulsion. Directed swimming can be supported by
magnetic fields, which simultaneously provide a versatile means of remote actuation. Thus, we analyze the motion of a straight microswimmer composed of three magnetizable beads connected by two elastic links. The swimming mechanism is based on oriented external
magnetic fields that oscillate in magnitude. Through induced reversible hysteretic collapse of the two segments of the swimmer, the two pairs of beads jump into contact and separate nonreciprocally. Due to higher-order hydrodynamic interactions, net displacement results after each cycle. Different microswimmers can be tuned to different driving amplitudes and frequencies, allowing for simultaneous independent control by just one external
magnetic field. The swimmer geometry and
magnetic field shape are optimized for maximum swimming speed using an evolutionary optimization strategy. Thanks to the simple working principle, an experimental realization of such a microrobot seems feasible and may open new approaches for microinvasive medical interventions such as targeted drug delivery.
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Medical Physics
Racket Kinematics and Ball Performance During the Forehand Reverse Flick: A Pilot Comparison With the Backhand Flick in Table Tennis
Pengfei Jin, Jie Ren, Chen Yang et al. (+6 more)
Background Following changes in table tennis ball materials, offensive returns have become more important for initiating sustained topspin offense. However, using the backhand flick (BF) to return forehand short balls often increases the difficulty of recovery and continuity, revealing a technical gap. This study preliminarily verified a novel forehand short return technique, the forehand reverse flick (FRF), and analyzed its similarities and differences with the BF. Methods Four elite athletes completed seven consecutive days of FRF specific training. Infrared motion capture and ultra-high-speed cameras were used to collect data on racket kinematics, movement duration, and ball performance. Results The success rate of the FRF increased steadily, reaching 86%. Racket trajectories of the two techniques were highly similar along the X (r = 1) and Y (r = 0.99) axes but differed along the Z (r = -0.04) axis. Racket and ball velocities were comparable between techniques, whereas the FRF showed lower resultant acceleration (approximately 265.57 m/s) and required about 0.03 s more for movement duration. Ball velocity was comparable between techniques, for the ball
spin, the FRF generated lower
spin (approximately 76.61 r/s) about 64% of the BF value (approximately 120.13 r/s). The highest participant mean
spin rate reached 93 r/s, about 77% of the BF mean. Conclusion Overall, the FRF was found to have favorable learnability and training value, with potential for further optimization and competitive application.
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All authors Pengfei Jin, Jie Ren, Chen Yang, Qingtao Kong, Qingshan Zhang, Nan Gu, Bin Chen, Qin Zhang, Zhe Feng
Computational Physics · Cross-listed from cond-mat.stat-mech
Curvature-driven shifts of the Potts transition on spherical Fibonacci graphs: a graph-convolutional transfer-learning study
Zheng Zhou, Xu-Yang Hou and Hao Guo
We investigate the
ferromagnetic $q$-state Potts model on spherical Fibonacci graphs. These graphs are constructed by
embedding quasi-uniform sites on a sphere and defining interactions via a chord-distance cutoff chosen to yield a network approximating four-neighbor connectivity. By combining Swendsen-Wang cluster Monte Carlo simulations with graph convolutional networks (GCNs), which operate directly on the adjacency structure and node
spins, we develop a unified phase-classification framework applicable to both regular planar
lattices and curved, irregular spherical graphs.
Benchmarks on planar
lattices demonstrate an efficient transfer strategy: after a fixed binarization of Potts
spins into an effective Ising variable, a single GCN pretrained on the Ising model can localize the transition region for different $q$ values without retraining. Applying this strategy to spherical graphs, we find that
curvature- and defect-induced connectivity irregularities produce only modest shifts in the inferred transition temperatures relative to planar baselines. Further analysis shows that the
curvature-induced shift of the critical temperature is most pronounced at small $q$ and diminishes rapidly as $q$ increases; this trend is consistent with the physical picture that, in two dimensions, the Potts model undergoes a transition from a continuous phase transition to a weakly first-order one for $q>4$, accompanied by a pronounced reduction of the correlation length.
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Geophysics
Mud-Standoff Effect Correction Based on Open-Short Calibration and Resistivity Consistency-Constrained Iterative Inversion for Oil-Based Mud Imagers
Li Fengfeng, Feng Zhou, Wu Hongliang et al. (+4 more)
We propose a mud-standoff effect correction method and a set of approximate apparent resistivity inversion methods suitable for oil-based mud micro-resistivity imaging logging. To calibrate the influence of the mud layer on electrode measurement signals, this study integrates the Open-Short calibration(OSC) method with the three-layer impedance model of the oil-based mud resistivity imager. By treating the electrode and the mud layer as an integrated whole and simulating the open/short-
circuit states via the finite element method, the independent extraction of the mud layer impedance signal is achieved, and the formation impedance signal is separated from the total impedance. For fast inversion of formation resistivity, standoff thickness (mud layer thickness), and relative permittivity of formation, a resistivity consistency-constrained iterative inversion method is further proposed. In this method, the formation impedance is first converted into resistivity, and then the consistency residual of the resistivity at different frequencies is used as the objective function to invert the approximate apparent resistivity of the formation through an iterative optimization
algorithm. The effectiveness of the finite element-simulated OSC method, the objective function construction scheme, and the consistency inversion method is verified through both numerical models and an example of field data.
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All authors Li Fengfeng, Feng Zhou, Wu Hongliang, Zhang Hao, Tian Han, Liu Peng, Yuan Lixin
Instrumentation and Detectors
Monitoring of structural changes in materials under the exposure of ionization radiation using a vibrating wire
S.G. Arutunian, N.M. Manukyan, S.A. Hunanyan et al. (+8 more)
Ionizing radiation (X-rays,
proton beams) causes structural changes in materials. If a vibrating metallic wire is subjected to such radiation, the natural frequency of the wire is affected as a result of changes in the elastic characteristics of the material. This paper presents the results of experiments on the impact of X-ray radiation in the range of 100-165 keV and a
proton beam with energy 18 MeV on the structure of stainless steel wire. In case of
proton irradiation an irreversible change in the wire frequency was observed, which indicated residual changes in the structure of the wire material. X-ray diffractometry methods were used to analyze the structural changes.
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All authors S.G. Arutunian, N.M. Manukyan, S.A. Hunanyan, A.V. Margaryan, E.G. Lazareva, M.Chung, L.M. Lazarev, G.S. Harutyunyan, D.A. Poghosyan, N.B. Margaryan N.R. Aghamalyan, M.N. Nersisyan
Atomic Physics
Endcap-Type Paul Trap for Precision Spectroscopy and Studies of Controlled Interactions
Anand Prakash, Akhil Ayyadevara, E. Krishnakumar et al. (+5 more)
We present the design and fabrication of an endcap-type Paul trap. The trap is designed for studies with Ca$^{+}$ and Yb$^{+}$. The design, fabrication process, and characterization are presented in detail with a focus on trapping a single compensated ion at the rf node. A custom-built imaging system of $NA = 0.14$ and magnification $\approx 22 \times$ performs close to diffraction-limit and resolves multi-ion clusters. Controlled ion loading and characterization of the trap are performed using $^{40}$Ca$^{+}$. The experimentally determined quadrupole coefficient of the trap is $\approx 0.3$, which is very close to the design value. The relative frequency shift along the spectroscopy beam due to excess micromotion (EMM) is at the level of $3.5\times 10^{-18}$ for $^{40}$Ca$^{+}$. Applications of this trap encompass single-ion-based optical frequency standards, tests of fundamental physics, the study of mesoscopic Coulomb clusters, and the controlled interaction of a single ion with co-trapped atoms.
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All authors Anand Prakash, Akhil Ayyadevara, E. Krishnakumar, M. Ibrahim, K. M. Yatheendran, Subhadeep De, Sayan Patra, S. A. Rangwala
Optics
Ultralow-noise microwave oscillator via optical frequency division with a co-self-injection-locked miniature Fabry-Perot reference
Runlin Miao, Chao Zhou, Pan Han et al. (+5 more)
Optical frequency division (OFD) provides the purest microwaves by down-converting the stability of optical cavity references. State-of-the-art references typically rely on electronic co-Pound-Drever-
Hall locking to ultrahigh-Q microresonators-a complex approach that introduces servo bumps and increases footprint. Alternatively, optical co-self-injection-locking (co-SIL) offers inherent simplicity but is limited by the large thermo-refractive noise and confined mode volumes of integrated cavities. Here, we demonstrate a two-point OFD-based microwave oscillator that combines an ultrahigh-Q miniature Fabry-Perot cavity with optical co-SIL. Leveraging its low relative phase noise optical reference and combing with an integrated
soliton microcomb, the system generates a microwave with phase noise of -147 dBc/Hz at 4 kHz offset (scaled to 10 GHz)-performance rivalling most electronically stabilized systems. This work marries the superior noise floor of ultrahigh-Q cavities with the simplicity of optical locking, providing a compact, cost-effective, and field-deployable path to pure microwaves for next-generation communications, radar and metrology.
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All authors Runlin Miao, Chao Zhou, Pan Han, Mingxin Yang, Xing Zou, Ke Wei, Ke Yin, Tian Jiang
Optics
Physics-embedded neural computational electron microscopy for quantitative 4D nanometrology
Hao-Jin Wang, Liqun Shen, Xin-Ning Tian et al. (+5 more)
The fusion of rigorous physical laws with flexible data-driven learning represents a new frontier in scientific simulation, yet bridging the gap between physical interpretability and computational efficiency remains a grand challenge. In electron microscopy, this divide limits the ability to quantify three-dimensional topography from two-dimensional projections, fundamentally constraining our understanding of nanoscale structure-function relationships. Here, we present a physics-embedded neural computational microscopy framework that achieves metrological three-dimensional reconstruction by deeply coupling a differentiable electron-optical forward model with deep learning. By introducing a
Vision Field
Transformer as a high-speed, differentiable surrogate for physical process analysis simulations, we establish an end-to-end, self-supervised optimization loop that enforces strict physical consistency with hardware geometry. This synergy enables single-shot, quantitative three-dimensional nanometrology with precision comparable to atomic force microscopy but at orders of magnitude higher throughput. Furthermore, we demonstrate the capability for four-dimensional (3D real space plus time) in situ characterization by tracking the dynamic
evolution of surface nanostructure during copper redox, revealing hidden crystallographic kinetics invisible to conventional imaging. Our work not only redefines the limits of scanning electron microscopy but also establishes a generalizable archetype for solving ill-posed inverse problems across physical sciences, unlocking the full potential of simulation as a third pillar of discovery.
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All authors Hao-Jin Wang, Liqun Shen, Xin-Ning Tian, Lei Lei, Kexin Wang, Grigore Moldovan, Marc-Georg Willinger, Zhu-Jun Wang
Medical Physics
On optimization of Paganin's method for propagation-based X-ray phase-contrast imaging and tomography
Timur E. Gureyev, David M. Paganin, Ashkan Pakzad et al. (+1 more)
Paganin's method for image reconstruction in propagation-based phase-contrast X-ray imaging and
tomography has enjoyed broad acceptance in recent years, with over one thousand publications citing its use. The present paper discusses approaches to optimization of the method with respect to simple image quality metrics, such as signal-to-noise ratio and spatial resolution, as well as a reference-based metric corresponding to the relative mean squared difference between the reconstructed image and the "ground truth" image that would be obtained in a setup with perfect spatial resolution and no noise. The problem of optimization of the intrinsic regularization parameter of Paganin's method with respect to spatial resolution in the reconstructed image is studied in detail. It is also demonstrated that a combination of Paganin's method with a Tikhonov-regularized deconvolution of the point-spread function of the imaging system can provide significantly higher image quality compared to the standard version of the method. Analytical expressions for some relevant image quality metrics are obtained and compared with results of numerical simulations. Advantages and shortcomings of optimization approaches using a number of different image quality metrics are discussed. The results of this study are expected to be useful in practical X-ray imaging and training of deep machine learning models for image denoising and
segmentation.
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All authors Timur E. Gureyev, David M. Paganin, Ashkan Pakzad, Harry M. Quiney
Atomic Physics
What is a Schiff moment anyway?
Amar Vutha
Schiff moments of atomic
nuclei are of considerable interest to experiments searching for undiscovered new physics that breaks time-reversal
symmetry. I develop a simple picture of the Schiff moment of a charge distribution, and discuss the interaction of the Schiff moment of a
nucleus with the field produced by an electron in an atom.
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Optics
Programmable radio-frequency calculations in electromagnetic-wave domain
Shao Nan Chen, Zhan Ye Chen, Si Ran Wang et al. (+9 more)
Information metasurfaces have emerged as pivotal components in next-generation electronic systems, with significant progress in their applications to communication, radar, and sensing. However, the current researches are mainly focused on their physical structures and system functions, while
radio-frequency (RF) signal processing and calculation remain constrained to digital-domain operations. This reliance on digital conversion inherently increases hardware complexity and power consumption. To address this challenge, we propose a programmable RF calculation system based on a space-time-coding metasurface (STCM), which can control the wave-matter interactions through space-time-coding (STC) strategies and achieve direct RF calculations in the electromagnetic (EM) space in a reprogrammable way. Particularly, the fundamental signal operations -
Fourier transform and convolution - are implemented in the EM-wave domain successfully. We validate the RF calculation capabilities in radar scenarios, facilitating the accurate detection of target velocity and range. Theoretical analysis, numerical simulations, and experimental results collectively demonstrate that the STCM-based RF calculation system exhibits superior precision, enhanced operational efficiency, and notable cost-effectiveness, highlighting its significant potentials for the next-generation electronic system deployments.
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All authors Shao Nan Chen, Zhan Ye Chen, Si Ran Wang, Bi Rui, Jin Feng Kang, Zheng Xing Wang, Zhen Jie Qi, Lijie Wu, Hui Dong Li, Jun Yan Dai, Qiang Cheng, Tie Jun Cui
Plasma Physics
Effect of LH and ECR waves on plasma parameters in ADITYA Upgrade tokamak
S. Aich, S. Dolui, K. Singh et al. (+29 more)
The
plasma discharges in ADITYA Upgrade Tokamak are produced by means of
transformer action, in which Ohmically created
plasma is driven by means of a secondary loop voltage. Due to reduction of
plasma resistivity after a certain level of
plasma temperature, Ohmic heating becomes poor and further achievement of temperature needs other heating techniques. ADITYA-U tokamak is facilitated with a 42 GHz-500 kW Electron Cyclotron Resonant Heating (ECRH) system. Also, there is a Lower Hybrid Current Drive (LHCD) system installed and operated at 3.7 GHz for driving non-inductive
plasma current followed by the Ohmic current drive. Though an eventual impact in the rise of
plasma temperature and
plasma current due to the application of ECRH and LHCD respectively are very obvious, their energy coupling with the
plasma results in several interesting outcomes in a number of experimentally measured
plasma parameters. The present work addresses such impactful observations that are noticed and reported for the first time in ADITYA-U Tokamak.
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All authors S. Aich, S. Dolui, K. Singh, J. Ghosh, K.A. Jadeja, R.L. Tanna, K.M. Patel, K. Galodiya, A. Patel, L.K. Pradhan, B.K. Shukla, H. Mistry, J. Patel, H. Patel, D. Purohit, K. G. Parmar, P. K. Sharma, J. Kumar, B. Hegde, Abhijeet Kumar, Vismay Raulji, Praveenlal E. V., T. M. Macwan, R. Kumar, A. Kumar, A. Kumawat, H. Raj, I. Hauque, Komal, S. Banerjee, P. Verma, ADITYA-U team
Chemical Physics
Full symmetry-breaking of electronic and nuclear dynamics for low attosecond resolution of electronic chirality
Tianlv Xu, Jiawen Kong, Tianjing Zhou et al. (+5 more)
Attosecond science is an emerging topic where chirality plays a central role. Here we demonstrate subjecting iodoacetylene, a geometrically achiral molecule, to a pair of simulated non-ionizing ultrafast circularly polarized
laser pulses at the highest time resolution to date, by two orders of magnitude (3.87 attoseconds), of the continuously-valued S and R electronic chirality assignments. We partner the only vector-based
quantum chemical physics theory enabling full
symmetry-breaking with electronic and
nuclear dynamics simulations: the former does not require charge density differences or special
symmetry positions. The resulting 'easy' and 'hard' directions of the total electronic charge density motion are quantified as a cardioid-like morphology for the duration of the simulated
laser pulses and toroidal afterwards. Future research directions include determination of the underlying mechanism governing
chiral induced
spin selectivity, in addition to application to
chiral spin selective phenomena in opto-spintronics and exotic
superconductors, partnered with orbital-free density functional theory (OF-DFT).
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All authors Tianlv Xu, Jiawen Kong, Tianjing Zhou, Yan Wang, Jingqin Tu, Alireza Azizi, Steven R. Kirk, Samantha Jenkins
Medical Physics
Critical Shortfall in NIH Support for Medical Physics Research
Guillem Pratx, Wensha Yang and Matthew L Scarpelli
This report summarizes changes in federal research funding to the medical physics community between FY24 and FY25. By linking the AAPM membership database with NIH RePORTER records, we quantified the distribution of NIH funding for projects led by AAPM researchers. Although total NIH funding to AAPM members remained relatively stable across the two years, the composition of that funding shifted substantially. Competing (new and renewal) awards declined 50%, driven largely by an 80% collapse in new R01 grants from the National Cancer Institute (NCI). In contrast, noncompeting continuation awards increased by 10%, following a shift in how NIH funds multi-year projects. These changes occurred in the context of widespread disruptions to NIH review and grantmaking, including delayed study sections and more stringent administrative requirements. Federal funding is essential to sustaining innovation, supporting early-stage investigators, and ensuring that patients receive the best possible care. The trends identified here raise concerns about the long-term vitality and stability of the medical physics research pipeline.
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Optics · Cross-listed from gr-qc
Chiroptical effect induced by gravitational waves
Haorong Wu and Xilong Fan
We propose the gravitational analog of the chiroptical effect for the first time, demonstrating that gravitational waves (GWs) can induce a reversal of
photon chirality through the exchange of angular momentum, namely the
spin-2-gravitation chiroptical effect. By analyzing the interaction between
photon spin angular momentum (SAM) and GWs, we derive the selection rules governing this exchange, which are strictly dictated by the
spin-1 and
spin-2 nature of the electromagnetic and gravitational fields, respectively. We find that the gravitational chiroptical effect reflects the local nature of SAM which prevents the accumulation of gravitational perturbations over spatial phase windings, and offers a theoretically rigorous tool to probe the
chiral structure of GWs. This mechanism provides a novel observational pathway to constrain modified
gravity theories, measure the asymmetric properties of compact binaries, and explore parity-violating physics in the early universe.
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Plasma Physics
Discharge characteristics and parameter diagnosis of dielectric barrier discharge patterns in double-gap configuration
Tian Shuang, Zhang Han, Zhang Xi et al. (+4 more)
Pattern discharge is a common mode in dielectric barrier discharge (DBD) and has broad application prospects in various industrial fields, such as material surface treatment, environmental monitoring, and biomedical applications. In this work, a mixed gas of 75% argon and 25% air is used to generate a pattern discharge. A double-gap boundary composed of hexagonal configuration and square configuration is employed, and the gas pressure is fixed at 20 kPa. By varying the applied voltage amplitude, single-ring pattern, square-point-line pattern, square
lattice pattern, and annular-
lattice pattern are obtained for the first time. The discharge characteristics and their temporal correlation are studied using both optical method and electrical method. The results show that the discharge patterns exhibit multiple discharges in each half of the voltage cycle, and these discharges are temporally correlated with each other. Time-resolved discharge images of the square
lattice pattern are captured using an enhanced charge-coupled device (ICCD). The experimental results reveal that multiple discharges in a half-voltage cycle correspond to the ignition process of the pattern in the radial direction from the outside to the inside. The morphology of the square
lattice pattern observed by the naked eye is actually the result of the temporal superposition of luminescence from points at different positions in the
evolution process.
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All authors Tian Shuang, Zhang Han, Zhang Xi, Zhang Xuexue, Li Qing, Li Xuecehng, Run Junxia
Fluid Dynamics
Dynamic Water-Wave Tweezers
Jun Wang, Shanhe Pang, Zhiyuan Che et al. (+11 more)
Following a recent demonstration of stable trapping of floating particles by stationary (monochromatic) structured water waves [Nature 638, 394 (2025)], we report dynamic water-wave tweezers that enable controllable transport of the trapped particle along an arbitrary trajectory on the water surface. Furthermore, we demonstrate simultaneous transport of two trapped particles along different trajectories. We employ a triangular
lattice formed by the interference of three plane waves, which can trap particles, depending on the wave frequency and particle parameters, either at intensity maxima or at intensity zeros (
vortices). By introducing small frequency detunings of the interfering waves, we control 2D motion of the
lattice and trapped particles. This approach is robust and effective over a relatively broad range of particle sizes and wave frequencies, offering remarkable new possibilities for noncontact manipulation of floating (e.g., biological and soft-matter) objects in fluidic environments.
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All authors Jun Wang, Shanhe Pang, Zhiyuan Che, Chang Liu, Wenzhe Liu, Haoyu Xie, Shipeng Li, Zhongxia Du, Xilai Hu, Yanyong Li, Bo Wang, Lei Shi, Konstantin Y. Bliokh, Yijie Shen
Physics and Society
Dynamics of Multi-Agent Actor-Critic Learning in Stochastic Games: from Multistability and Chaos to Stable Cooperation
Yuxin Geng, Wolfram Barfuss, Feng Fu et al. (+1 more)
Achieving robust coordination and cooperation is a central challenge in multi-
agent reinforcement learning (MARL). Uncovering the mechanisms underlying such emergent behaviors calls for a dynamical understanding of learn processes. In this work, we investigate the dynamics of actor-critic
agents in
stochastic games, focusing on the impact of
entropy regularization. By leveraging time-scale separation, we derive the system's
evolution equations, which are then formally analyzed using dynamical systems theory. We find that in the constant-sum game of Matching Pennies, the system exhibits chaotic behavior.
Entropy regularization mitigates this chaos and drives the dynamics toward convergence to fair cooperation. In contrast, in the general-sum game of the Prisoner's Dilemma, the system displays multistability. Interestingly, the three stable
equilibria of the system correspond to the well-known ALLC (Always Cooperate), ALLD (Always Defect), and GRIM (Grim Trigger) strategies from evolutionary game theory (EGT).
Entropy regularization strengthens system resilience by enlarging the basin of attraction of the cooperative
equilibrium. Our findings reveal a close link between the mechanism of direct reciprocity in EGT and how cooperation emerges in MARL, offering insights for designing more robust and collaborative multi-
agent systems.
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All authors Yuxin Geng, Wolfram Barfuss, Feng Fu, Xingru Chen
Physics Education
Living in the tensions: Investigations of gender performativity in STEM
Smith Strain, Noah Leibnitz, Reagan Ruben et al. (+2 more)
In this work, we present the results of semi-structured interviews with four women to explore how they perceive themselves with respect to three gender constructs (femininity, masculinity, androgyny), and how they believe others perceive them. All the women highlighted the performative nature of gender in science, technology, engineering, and mathematics (STEM), citing (1) stereotypes that women are not analytical thinkers, or femininity being associated with "being stupid"; (2) the pressure to conform to the masculine norms of STEM, and (3) a pressure to perform to prove that they belong in STEM. Some of these women aligned their own perceptions of their gender with these norms, while others expressed frustration with the tension between their gender and how that is perceived by peers in STEM. This work suggests that conceptualizing gender as performance is a useful lens for understanding the oppression and underrepresentation of women and gender minorities in STEM.
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All authors Smith Strain, Noah Leibnitz, Reagan Ruben, Yangqiuting Li, Eric Burkholder
Plasma Physics
Guiding-center dynamics in a screw-pinch magnetic field
Alain J. Brizard
The guiding-center dynamics of charged particles moving in a doubly-symmetric screw-pinch
magnetic field is investigated. In particular, we verify that Kruskal's adiabatic-invariant series expansion of the radial action integral associated with the reduced full-orbit radial motion matches the perturbation expansion of the
magnetic-moment gyroaction up to first order in
magnetic-field non-uniformity. Because the radial action integral is an exact invariant of the full-orbit dynamics, the
magnetic moment is therefore represented as non-perturbative integral expression, which can be used to test the validity of the guiding-center approximation.
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Physics and Society
Symmetry Breaking, Hysteresis, and Convergence to the Mean Voter in two-party Spatial Competition
Daniel Miranda Machado and Roberto Venegeroles
Classical spatial models of two-party competition typically predict convergence to the median voter, yet real-world party systems often exhibit persistent and asymmetric polarization. We develop a spatial model of two-party competition in which voters evaluate parties through general satisfaction functions, and a width parameter $q$ captures how tolerant they are of ideological distance. This parameter governs the balance between centripetal and centrifugal incentives and acts as the bifurcation parameter governing
equilibrium configurations. Under mild regularity assumptions, we characterize Nash
equilibria through center-distance coordinates, which separate the endogenous political center from polarization. When the voter density is symmetric, the reduced
equilibrium condition exhibits a generic supercritical pitchfork bifurcation at a critical value $q_{c}$. Above $q_{c}$, the unique stable
equilibrium features convergence to the center, recovering the classical median voter result, whereas below it two symmetric polarized
equilibria arise. Asymmetry in the voter distribution unfolds the pitchfork, producing drift in the endogenous center and asymmetric polarized
equilibria. The resulting
equilibrium diagram has an S-shaped geometry that generates hysteresis, allowing polarization to persist even after tolerance returns to levels that would support convergence in a symmetric environment. In the high-tolerance regime, we show that the unique non-polarized
equilibrium converges to the mean of the voter distribution, while the median is recovered only under
symmetry. Hence, unlike the Hotelling–Downs model, where convergence to the median is universal, the median voter appears here as an asymptotic
benchmark rather than a robust predictor.
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