Instrumentation and Detectors
Hit-rate capability of a silicon strip detector module for decay positron detection in the J-PARC muon $g-2$/EDM experiment
Ryuto Azuma, Katsunori Awa, Shunsuke Doi et al. (+34 more)
In the J-PARC
muon $g-2$/EDM experiment, a silicon strip detector will be used to detect positrons from
muon decays. The detector consists of planes of detector modules arranged radially. The expected maximum hit rate reaches 1.4~MHz per sensor strip, and achieving high detection efficiency even under such hit-rate conditions is a key performance requirement. We have developed the smallest unit of the detector module, and its performance was evaluated using a
muon beam at the J-PARC MLF H-line. The specifications of the detector module and the evaluated hit-rate capability are described in this article.
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All authors Ryuto Azuma, Katsunori Awa, Shunsuke Doi, Yowichi Fujita, Seiso Fukumura, Yu Goto, Ryotaro Honda, Sohtaro Kanda, Tetsuichi Kishishita, Tatsuya Kume, Tsutomu Mibe, Yukiharu Murata, Shoichiro Nishimura, Shinji Ogawa, Yuta Okazaki, Naohito Saito, Maki Sakakibara, Osamu Sasaki, Taiki Sato, Yutaro Sato, Yoshiaki Seino, Hiroshi Sendai, Koichiro Shimomura, Shohei Shirabe, Masayoshi Shoji, Patrick Strasser, Taikan Suehara, Shiori Sugahara, Junichi Suzuki, Toshikazu Takatomi, Manobu M. Tanaka, Junji Tojo, Hiroyuki A. Torii, Takashi Yamanaka, Hiroshi Yamaoka, Takayuki Yamazaki, Tamaki Yoshioka
Geophysics · Cross-listed from cs.CE
Phase-field analysis of fracture in heterogeneous wellbore systems: effects of casing eccentricity and cement-formation interface strength
Tharunsarathy Sachithanantham, Wasim Niyaz Munshi, Chandrasekhar Annavarapu et al. (+1 more)
Predicting the initiation and propagation of cracks in heterogeneous wellbore systems under complex in-situ conditions remains challenging. We present a hybrid phase-field fracture framework to model crack growth in heterogeneous wellbore systems with weak interfaces. The framework is first validated against
benchmark problems with available analytical and numerical solutions. Subsequently, numerical experiments are conducted to isolate the effects of interface strength and casing eccentricity on crack growth. The results show that casing eccentricity strongly influences both the pressure at crack initiation and the resulting crack paths, reducing the crack initiation pressure by up to 30% relative to the concentric configuration. For the examples considered here, beyond a critical eccentricity threshold of 50%, localized shear stresses drive the nucleation of inclined cracks in the rock formation in addition to radial cracking – a failure mode absent in concentric configurations. For sufficiently weak interfaces (i.e., interfaces with 30% of the toughness of the surrounding bulk material), radially propagating cracks in the cement sheath are deflected along the interface rather than penetrating into the rock formation. This deflection delays stress relaxation within the sheath, promotes the nucleation of additional radial cracks, and increases the risk of sustained casing pressure and wellbore failure. Finally, a three-dimensional simulation reveals depth-dependent crack nucleation, stress-shadow effects that suppress full-depth crack growth, and crack coalescence along the cement-rock interface – phenomena that are fundamentally inaccessible under plane-strain assumptions – demonstrating the applicability of the framework to realistic heterogeneous wellbore systems.
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All authors Tharunsarathy Sachithanantham, Wasim Niyaz Munshi, Chandrasekhar Annavarapu, Birendra Jha
Geophysics
Resonant lunar tides of Earth's core and basal magma ocean
Murray B.C. Kiernan, Hamish C.F.C. Hay, David W. Rees Jones et al. (+2 more)
Earth's
magnetic field is generated by fluid motion in the
liquid-metal core and has been active for billions of years. However, prior to the onset of inner-core growth, the sources of mechanical power that drove the geodynamo remain uncertain. During this period, the core may have been overlain by a basal magma ocean (BMO), creating two immiscible fluid layers separated by a density interface, beneath the solid mantle. We develop a theory for lunar tides in this core–BMO system, in which the
tidal potential acts on the density contrast between the two layers. The resulting dynamics differ fundamentally from previous models driven by imposed deformation of the core's bounding envelope. In the inviscid limit, the response transitions from an
equilibrium tide to an interfacial
gravity wave as forcing frequency increases. The two regimes are separated by a resonance that occurs when the forcing frequency matches the natural frequency of the degree-2, order-2 interfacial mode. The inviscid core flow is formally identical to the canonical elliptical
vortex, linking the problem to the theory of elliptical instability. Finite viscosity regularises the resonance, introduces phase lag and generates oscillatory boundary layers. Combined with parameterised models of lunar recession and BMO crystallisation, the theory predicts enhanced core-boundary ellipticity, core-flow speed,
magnetic Reynolds number and instability metrics, particularly near resonance. These results identify a previously unexplored mechanism for tidally driven flow in differentiated planetary bodies and show that a BMO can enhance
tidal coupling to the core, potentially contributing to dynamo action.
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All authors Murray B.C. Kiernan, Hamish C.F.C. Hay, David W. Rees Jones, James F.J. Bryson, Richard F. Katz
Biological Physics · Cross-listed from cond-mat.stat-mech
Thermodynamic Uncertainty Relation For a Multi-Phase Alternating Renewal Random Walk
Fatemeh Karimi and Farhad H. Jafarpour
Thermodynamic Uncertainty Relations (TURs) impose universal bounds linking current precision to
entropy production in nonequilibrium systems. While general bounds like the Proesmans–Van den Broeck (PV) relation provide a broad framework, they often remain loose for processes characterized by renewal events. In this work, we derive a generalized entropic bound for current fluctuations in renewal-reward processes. By utilizing a rigorous variance decomposition within the framework of renewal-reward theory, we obtain a model-independent bound that is not only rigorous but tighter than the standard PV relation. Notably, in the linear-response regime, our bound correctly scales with the renewal rate and identifies a precision penalty arising from cycle-length fluctuations. These results provide a physically informative constraint on the precision of run-and-tumble-type dynamics and highlight the universal limits of transport in complex
stochastic walkers.
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Optics
Integrated tunable mid-infrared electro-optic frequency comb generator based on nonlinear conversion
Pierre Didier, Prakhar Jain, Tristan Kuttner et al. (+2 more)
Mid-infrared frequency combs enable highly selective and sensitive molecular spectroscopy by leveraging the strong vibrational transitions in this spectral region. Among these, there is a particular need for compact, tunable sources with electronic control over comb parameters for integrated sensing platforms. In this work, we demonstrate a mid-infrared electro-optic frequency comb source based on nonlinear frequency conversion in thin film lithium niobate. The system combines a near-infrared pump, amplitude-modulated using an integrated Mach-Zehnder modulator for lock-in detection, with a telecom-band electro-optic comb generated via a double-pass phase modulation scheme. Mid-infrared comb generation is achieved through difference frequency generation in a periodically poled waveguide. By tuning the telecom seed
laser and the chip temperature, we obtain mid-infrared combs with a bandwidth of approximately 6 nm and center wavelength tunability of over 200 nm. The comb free spectral range is directly controlled via the applied
radio-frequency modulation. Operation across multiple integrated photonic
circuits reaching wavelengths up to 3.7 $\mu$m is demonstrated. Furthermore, dual-tone EO comb generation in the mid-infrared is realized. To our knowledge, this is the first integrated mid-infrared electro-optic comb source offering independent electronic control of both center wavelength and comb spacing.
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All authors Pierre Didier, Prakhar Jain, Tristan Kuttner, Oliver Pitz, Rachel Grange
Optics
Neural network inverse design of nanophotonic scintillators
Nathan Regev, Avner Shultzman, Francis Loignon-Houle et al. (+2 more)
Scintillators are materials converting high-energy radiation into optical light, essential in a range of technologies such as medical imaging systems and security scanners. Scintillator development and optimization have remained limited by the complexity of their underlying physics, involving
stochastic cascades of electron-electron, electron-
phonon, and electron-
photon interactions. Such processes are typically modeled by non-differentiable Monte Carlo simulations, limiting the applicability of machine learning for scintillator development. Here we present a physics-informed neural network that learns the scintillation cascade process from the incident high-energy particle to
photon emission, substantially accelerating scintillator design and optimization. Combining this neural network with photonic simulations enables end-to-end differentiable optimization of the scintillator geometry. This allows us to optimize for arbitrary figures of merit, such as specific target emission patterns.. We demonstrate the concept and characterize it relative to previous approaches by inverse design of nanophotonic scintillators for X-ray imaging.
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All authors Nathan Regev, Avner Shultzman, Francis Loignon-Houle, Charles Roques-Carmes, Ido Kaminer
Optics
Writing and readout of luminescent defects on an optical nanofiber using an electron beam
Yining Xuan and Mark Sadgrove
We demonstrate the writing and readout of groups of luminescent defects on an optical nanofiber (ONF), with readout performed through the fiber modes. In the write step, a focused electron beam incident on the fiber surface created luminescent defect centers in the fiber's silica in a region of diameter $\sim200$ nm localized about the beam center. In the readout step, the electron beam was scanned over the fiber and the induced cathodoluminescence from the defects was coupled into the ONF and detected. The regions with electron beam-induced luminescent defects exhibited a strongly enhanced optical signal, despite minimal observable change in the fiber surface, as judged by secondary electron imaging over the same region. Spectral measurements show that the enhanced luminescence stems from the creation of both oxygen deficiency centers (ODCs) and non-bridging oxygen hole centers (NBOHCs) by the electron beam.
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Computational Physics · Cross-listed from cond-mat.mtrl-sci
Dynamically suppressed lattice rotations in SrTiO$_3$ as a basis for photo-induced ferroelectricity
Huaiyu Hugo Wang, Michael Fechner, Giovanni De Vecchi et al. (+22 more)
Photo-induced ferroelectricity in the
quantum paraelectric SrTiO$_3$ involves the dynamical interplay between a coherently driven Ti-O stretching vibration and multiple structural degrees of freedom, including antiferrodistortive rotations, strain, and the polar mode instability. In the high-temperature cubic phase, in the absence of average antiferrodistortion, time-resolved X-ray diffuse scattering has evidenced a correlation between a photo-induced reduction in antiferrodistortive fluctuations and the emergence of ferroelectric order. Here, we complement these measurements with time-resolved elastic X-ray diffraction in the low-temperature tetragonal phase, in which antiferrodistortive fluctuations are small but a finite average rotation has set in. In this phase, we observe a long-lived reduction of the
equilibrium antiferrodistortive rotation angle. A unified theory of the nonlinear
lattice dynamics based on first-principles calculations describes the dynamics in both high-temperature cubic and low-temperature tetragonal phases, providing a basis for light-induced ferroelectricity in SrTiO$_3$.
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All authors Huaiyu Hugo Wang, Michael Fechner, Giovanni De Vecchi, Sylvia L. Griffitt, Gal Orenstein, Jade Stanton, Viktor Krapivin, Man T. Wong, Zhuquan Zhang, Mina Bionta, Vincent Esposito, Meredith Henstridge, Matthias C. Hoffmann, Patrick L. Kramer, Zach Porter, Ryan A. Duncan, Takahiro Sato, Soyeun K. Kim, Hasan Yavas, Samuel Teitelbaum, Keith Nelson, Ankit S. Disa, Michael F"orst, Mariano Trigo, Andrea Cavalleri
Optics
Wavelength-Multiplexed 2D Beam Steering via a Passive Diffractive Network
Che-Yung Shen, Yuhang Li, Cagatay Isil et al. (+3 more)
We introduce a wavelength-addressable diffractive optical network that transforms illumination wavelength into a high-dimensional control parameter for arbitrarily programmable 2D beam steering. The proposed passive architecture comprises cascaded spatially optimized diffractive layers, jointly designed using deep learning, to rapidly map distinct wavelengths to predefined/desired output angles. Unlike conventional single-layer dispersive optical elements, which are physically restricted to 1D linear mapping, this framework harnesses complex wavefront transformations to utilize the illumination wavelength as an intrinsic addressing key for arbitrary 2D beam steering, eliminating the need for mechanical scanning or electronic phase control. We numerically demonstrate wavelength-controlled beam steering across 625 wavelength channels spanning 400-750 nm, realizing a 25 x 25 array of independently addressable beam positions with subwavelength positioning accuracy and high channel fidelity. Unlike conventional gratings, which constrain wavelength routing to a linear trajectory, the proposed diffractive network performs nonlocal wavefront transformations, enabling arbitrary wavelength-to-angle mappings across a 2D field of view. We further validate the proposed framework experimentally in both the terahertz and visible spectral regimes, demonstrating wavelength-multiplexed beam steering using 3D fabricated passive diffractive layers at terahertz frequencies and phase-only spatial light modulators in the visible spectrum. This wavelength-addressable diffractive architecture establishes a compact and scalable paradigm for high-speed programmable beam steering, with potential applications in optical communications, routing, imaging, sensing, and emerging photonic information-processing systems.
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All authors Che-Yung Shen, Yuhang Li, Cagatay Isil, Tianyi Gan, Mona Jarrahi, Aydogan Ozcan
Optics · Cross-listed from cond-mat.mes-hall
Hidden chirality and half-vortex formation in exciton-polariton condensates
A. N. Osipov, I. Y. Chestnov, P. G. Lagoudakis et al. (+1 more)
We show that a radially symmetric, nonresonantly pumped spinor
exciton-polariton condensate can acquire chirality without a rotating drive,
chiral geometry, or pump orbital angular momentum.
Spin relaxation in a two-reservoir system shifts the reservoir-induced blueshift relative to the gain profile, creating an effective non-Hermitian
chiral potential. A reduced angular-mode theory reveals tunable exceptional points and non-reciprocal coupling between counter-rotating modes. Full driven-dissipative Gross-Pitaevskii simulations show that this hidden chirality enables all-optical formation of
spin-selective half-
vortices.
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All authors A. N. Osipov, I. Y. Chestnov, P. G. Lagoudakis, A. V. Yulin
Computational Physics · Cross-listed from cs.CE
Graphical conditional generative modeling for digital twin modeling
Zongren Zou, Théo Bourdais, Ricardo Baptista et al. (+1 more)
Digital twin modeling, including control and data assimilation under model uncertainty, often faces an open-ended fidelity problem: adding variables, data streams, and time scales can indefinitely increase model complexity, ultimately producing systems that are difficult to maintain, validate, interpret, and use for stress or safety testing. As an alternative, one can seek parsimonious
stochastic surrogate models built only on the variables needed to describe the relevant quantities of interest. We introduce a framework for discovering such variables from observational data by identifying which candidate inputs influence the full conditional law of a target quantity, rather than only its conditional mean. This distinction is essential in
stochastic, coarse-grained, or partially observed systems, where dependencies may appear through changes in variability, tail behavior, multimodality, or uncertainty rather than through deterministic functional relationships. The framework couples conditional generative modeling, which learns the conditional distribution of the target given candidate inputs, with Gaussian-process-based analysis of variance (through kernel mode decomposition), which enables iterative
pruning of non-influential inputs and interpretable structure discovery. In control settings, the resulting surrogate can be interpreted as a learned Markov decision process: the method identifies not only a transition model, but also the state, action, and
memory variables needed to make the learned dynamics effectively Markovian. Across examples involving
stochastic dynamical systems, missing variables, PDE control, reinforcement learning, and economic data, the discovered structures yield interpretable
stochastic surrogates whose downstream performance is comparable to models trained on the full variable set.
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All authors Zongren Zou, Théo Bourdais, Ricardo Baptista, Houman Owhadi
Computational Physics · Cross-listed from cond-mat.str-el
symveig: Verified eigenvalue enclosures for symmetry-decomposed Hermitian matrices
Sarang Vehale and Ritu Goel
Exact diagonalization of
quantum lattice Hamiltonians returns floating-point
eigenvalues whose accuracy is not certified: rounding error, eigensolver behaviour, and ill-conditioning can corrupt a result without warning. We present symveig, a pure NumPy/SciPy package that computes rigorous, machine-checkable enclosures of all
eigenvalues of a Hermitian
matrix, with an optional
symmetry-sector decomposition. For a
matrix that commutes with an abelian conserved quantity diagonal in the working basis (for example the total magnetization of a
spin model), the package verifies each
symmetry sector independently. Because each sector block is much smaller than the full
matrix, this yields enclosures that are both tighter (by a factor of $3$-$9$ across system sizes $L = 4$-$12$) and dramatically faster (a wall-clock speedup of up to $130\times$ at $L = 12$) than verifying the full
matrix, while never forming or diagonalizing it. Every enclosure half-width is a guaranteed upper bound on the distance from a computed
eigenvalue to the nearest true
eigenvalue under IEEE~754 round-to-nearest arithmetic, obtained by explicit floating-point error analysis with no heuristic slack. The implementation requires neither INTLAB nor MATLAB, bringing rigorously verified
eigenvalue enclosure into the standard scientific-Python stack used in computational physics. We validate the package on $1$D Heisenberg (open and periodic), $J_1$-$J_2$ Heisenberg, and $2$D Heisenberg
lattices, confirming that every computed
eigenvalue is contained in its enclosure across all tested configurations.
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Plasma Physics · Cross-listed from math.AP
Asymptotic stability of Bernstein-Greene-Kruskal (BGK) waves, Landau Damping, and scattering theory
Ricardo Weder
We consider the two species (electrons and positive charged ions) Vlasov-Poisson system linearized around BGK waves. We formulate the problem as an equivalent Vlasov-Ampère system, that we write as a system of Schrödinger type in an appropriate
Hilbert space, and with a selfadjoint Vlasov-Ampère operator as a
Hamiltonian. We develop a complete stationary scattering theory. We identify the absolutely continuous spectrum and the singular spectrum of the Vlasov-Ampère operator, we construct the generalized
Fourier maps, we prove that the wave operators exist, are complete, satisfy Birman's invariance principle, and that the stationary formulae hold. Using these results we prove that the BGK waves are asymptotically stable. We obtain a precise description of the large time behaviour of the solutions to the Vlasov-Ampère system Namely,for large times the phase-space densities of electrons and ions are asymptotic to the phase-space densities of solutions of the unperturbed Vlasov-Ampère system. This implies that they follow the trajectories of solutions to Newton's equations for electrons and ions with the potential of the BGK wave, in the sense that they are transported along these trajectories. Furthermore, we prove that Landau damping holds, that is to say, the electric field tends to zero in pointwise sense for large times.
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Computational Physics · Cross-listed from math.NA
Infinite-lattice discrete Calderón projection via the lattice Green's function for active noise shielding and confinement
Qing Xia
We construct an infinite-
lattice discrete Calderón projection for the Helmholtz equation by convolution with the
lattice Green's function (LGF), and apply it to active noise shielding and confinement on Cartesian grids with arbitrary geometry. The LGF fixes the outgoing radiation condition and removes the geometry-dependent auxiliary Helmholtz problem and artificial outer boundary from the projection and control synthesis; its finite numerical tabulation depends only on $(h,k)$ and is reusable across geometries. We prove idempotence, characterize the range as the trace space of interior
lattice-Helmholtz solutions, and establish range equivalence with a well-posed Tsynkov-type projection. The two projectors coincide as operators when the auxiliary problem reproduces the exact
lattice radiation condition. A capacity-
matrix realization yields closed-form shielding and confinement densities supported on the exterior and interior sublayers of a single
lattice boundary strip, respectively. For pure-noise shielding, exterior-sublayer measurements suffice under explicit invertibility assumptions; preservation of an unknown wanted interior field requires the full strip trace. Experiments on circular, L-shaped, and
star-shaped regions verify machine-precision cancellation for LGF-consistent sources and near-second-order convergence for analytic plane waves and point sources. Conditioning and measurement noise tests quantify the configuration dependence of the reconstruction.
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Applied Physics
In-Plane Q Anisotropy of Higher-Order XBARs in 128{\deg}Y-Cut Lithium Niobate
Byeongjin Kim, Ian Anderson and Ruochen Lu
128$^\circ$Y-cut lithium niobate (LN) laterally field-excited higher-order antisymmetric bulk acoustic resonators (XBARs) have attracted interest for high-frequency acoustic devices thanks to their high electromechanical coupling coefficient ($k^2$), high quality factor ($Q$) from low metal coverage ratio, and thickness-defined resonant frequency. So far, the in-plane orientation of these resonators is commonly chosen to maximize $k^2$, thereby maximizing bandwidth. More recently, in-plane-rotated XBARs in 128$^\circ$Y-cut LN have been built to provide greater design flexibility in filter synthesis. However, the in-plane anisotropy of $Q$ has been far less explored. This leaves an important gap in understanding whether the propagation direction that determines $k^2$ also affects $Q$. In this work, we investigate the anisotropic $Q$ of higher-order antisymmetric modes (namely, A$_3$, A$_5$, and A$_7$) in 500-nm-thick 128$^\circ$Y-cut LN on Si. By characterizing resonator performance in various in-plane orientations, we observe that both Bode $Q$ and $Q_{\mathrm{3dB}, f_p}$ show minimum values at 90$^\circ$ to the material x-axis and maximum values around 0$^\circ$, following a trend similar to $k^2$. The A$_3$, A$_5$, and A$_7$ modes around 10.4, 17, and 24 GHz exhibit averaged Bode $Q$/$Q_{\mathrm{3dB}, f_p}$ values of 735/556, 204/149, and 59/37, respectively. At 90$^\circ$, the average Bode $Q$ values are reduced to 66, 9, and 12. Finite element analysis (FEA) results suggest that the orientation-dependent degradation of $Q$ near 90$^\circ$ is associated with stronger transverse displacement near the inactive and anchor regions, resulting in enhanced energy leakage. These results reveal an orientation-dependent loss pathway in 128$^\circ$Y-cut LN XBARs and provide design guidance for jointly optimizing $k^2$ and $Q$.
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History and Philosophy of Physics · Cross-listed from quant-ph
The Distribution Postulate in Algorithmic Bohmian Mechanics
Jeffrey A. Barrett, Eddy Keming Chen and Josiah Lopez-Wild
In order to make the right empirical predictions Bohmian mechanics requires a special statistical boundary condition – the distribution postulate – but it is unclear how best to understand this condition. We show how one might use the theory of algorithmic randomness to formulate the distribution postulate as an objective constraining law. The framework requires us to say something about admissible
quantum-mechanical states and measurements. In return, algorithmic Bohmian mechanics (aBM) guarantees the standard Born statistics for a collection of canonical
quantum experiments in the limit, not just with high probability. The algorithmic distribution postulate provides a sharp typicality condition, clarifies the status of
quantum probabilities in the deterministic theory, and provides a concrete example of how notions provided by the theory of algorithmic randomness can aid in specifying the content of a physical law.
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Chemical Physics · Cross-listed from cond-mat.soft
Phase Behavior of Unilamellar Hybrid Lipid-Diblock Copolymer Membranes
James F. Tallman, Junyu Wu and Antonia Statt
Hybrid lipid block copolymer membranes are promising for many applications in drug delivery, single molecule detection, in-membrane
protein folding, and synthetic
cells. However, rational design is difficult due to the many design parameters which determine the nano- and micron-scale morphology and properties. In this work, we propose a physically-informed framework which incorporates chemical immiscibility, hydrophobic thickness mismatch and
geometric constraints to predict the morphology of hybrid membranes. For this purpose, we extend existing theory for amphiphilic monolayers to model the thickness of diblock copolymer
bilayers, demonstrating that both the hydrophobic and hydrophilic block lengths determine the thickness. We identify and rationalize the four primary membrane morphologies observed: mixed, laterally phase-separated, unzipped (thick-thin coexistence), and
polymer-rich. Specifically, chemical immiscibility differentiates mixed membranes from laterally phase separated membranes, and hydrophobic mismatch drives transitions to unzipped or
polymer-rich morphologies. Areal density, finally, determines the crossover between unzipped and
polymer-rich states. We validate our theoretical predictions using coarse-grained molecular dynamics across a broad parameter space, including multiple lipid species (DOPC, DPPC),
polymer species (1,4 PBD-b-PEO, 1,2 PBD-b-PEO, PE-b-PEO), block lengths, temperatures, and compositions. The resulting phase maps unify previously reported experimental and simulation observations and enable a generic and mechanistic understanding for the effect of system parameters on the nanoscale morphology.
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Optics
Spatiotemporally Interleaved Homodyne Photonic Tensor Core
Yun-Long Nie, Hang Song, De-Hui Huang et al. (+6 more)
Photonic computing provides ultrahigh bandwidth, low latency and intrinsic parallelism, making it a promising route beyond the scaling limits of electronic computing. However, existing on-chip photonic computing systems remain constrained by persistent trade-offs among high-speed modulation, energy efficiency and large-scale integration, limiting their system-level advantages. Here we present a spatiotemporally interleaved homodyne photonic tensor core implemented on a thin-film lithium niobate (TFLN) platform. By integrating a homodyne photonic
matrix with a bus-readout time-integrating array, this architecture scales down the high-speed digital-to-analog and electro-optic interconversion hardware overhead required for photonic
matrix operations from O(n^2) to O(n), thereby unlocking system-level scalability. Moreover, the architecture employs orthogonal horizontal and vertical crossbars to route data and weight signals independently, eliminating the intrinsic beam combining loss while enabling ultrahigh-speed synchronous updates of both data and weights. Collectively, these features provide a scalable and hardware-efficient foundation for high-bandwidth photonic processors targeting general-purpose artificial intelligence (AI) computing.
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All authors Yun-Long Nie, Hang Song, De-Hui Huang, Yi Xie, Yu-Xuan Fu, Jian-Peng Dou, Xiao-Yun Xu, Hao Tang, Xian-Min Jin
Chemical Physics
Stitching Molecular Worlds Together with Physics-Coupled Diffusion Models
Yanbin Wang, Yajie Cai and Ming Chen
Complex chemical systems often contain multiple components or large molecules, giving rise to substantial chemical and conformational complexity. Modeling the structures of these systems is crucial for mechanistic understanding of chemical processes and rational design, but remains highly challenging for both conventional theoretical approaches and machine learning. Here, we introduce physical-interaction-coupled
diffusion models (PICDiff), a framework that couples independently trained
diffusion models for subsystems of a complex system through explicit bonded and nonbonded interactions during inference. PICDiff reduces the difficulty of applying generative models to chemically and conformationally complex systems by decomposing them into smaller subsystems that are less complex and more amenable to machine-learning-based modeling. Using peptide-
polymer binding and
polymer conformation sampling as examples, we demonstrate that PICDiff can quantitatively sample conformations and model the thermodynamics of complex chemical systems. These results show that PICDiff provides a general and practical approach for modeling complex chemical systems by combining learned models of simpler molecular subsystems through physical interactions.
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Atomic Physics
Doppler-shifted X-ray Spectroscopy of Nonradiative Electron Capture in Relativistic Collisions of Xe54+ Ions with Kr and Xe Atoms
Bian Yang, Deyang Yu, Konstantin N. Lyashchenko et al. (+13 more)
We present an angular-resolved Doppler spectroscopy study of nonradiative electron capture in relativistic collisions of bare Xe54+ ions with Kr and Xe gas targets at the HIRFL-CSR storage ring. The energy spectra and angular distributions of X-rays emitted from fast-moving down-charged projectiles were measured at five observation angles of 35{\deg}, 60{\deg}, 90{\deg}, 120{\deg}, and 145{\deg} and three collision energies of 95, 146, and 197 MeV/u by employing the effect of Doppler shift. The transition intensities of Xe53+ ions with small energy differences were precisely determined. In symmetric Xe54+ \to Xe collisions, the transition intensities of Xe53+ and Xe52+ ions were identified when X-rays emitted by projectiles overlapped with K X-rays arising from target ionization. The anisotropy parameters of the K{\alpha_1}(+M2) transition were derived from the angular emission patterns of the corresponding spectral lines. The relative populations of the L, M, and N-shell excited levels of Xe53+ and Xe52+ were further deduced from the intensity ratios of I(Ly-{\beta})/I(Ly-{\alpha}), I(Ly-{\gamma})/I(Ly-{\alpha}), and I(K{\alpha})/I(Ly-{\alpha}). The energy dependence of the population of excited projectile levels was obtained for both targets. Furthermore, the experimental results were compared with theoretical calculations of nonradiative single- and double-electron capture based on the relativistic eikonal approximation and the independent-electron approximation. These findings provide valuable insights into the
magnetic-sublevel population and n-resolved state-selective population of excited states produced in relativistic collisions of highly charged heavy ions with multi-electron atoms.
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All authors Bian Yang, Deyang Yu, Konstantin N. Lyashchenko, Caojie Shao, Zhongwen Wu, Mingwu Zhang, Oleg Yu. Andreev, Junliang Liu, Zhangyong Song, Yingli Xue, Wei Wang, Fangfang Ruan, Yehong Wu, Rongchun Lu, Chenzhong Dong, Xiaohong Cai
Plasma Physics
Quasiparticles and ion cooling by an electron beam in a strong magnetic field
D.M.Popov and A.I.Milstein
The frictional force arising from the interaction of ions with a magnetized electron beam in a strong
magnetic field is investigated. The problem is reduced to the interaction of quasiparticles, or Larmor circles, with ions. A
Hamiltonian describing this interaction is derived. The role of various impact parameters in the process of ion cooling is elucidated. The cases of both positively and negatively charged ions are considered.
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Optics
Spatiotemporal Tracking of Optical Speckles in Turbulent Atmospheric Propagation
Travis M. Crumpton and Luat T. Vuong
The speckle fields produced by optical beam propagation through atmospheric
turbulence are typically described using ensemble-averaged intensity and coherence statistics, which obscure the speckle-level dynamics. Here, we investigate the spatiotemporal
evolution of speckles generated during Gaussian beam propagation through
turbulence by explicitly tracking them as discrete resolvable substructures. We quantify object-level persistence, transverse extent, and trajectories as functions of propagation distance,
turbulence strength, and source-plane beam width. Under fixed detection criteria, we observe that a subset of these speckles exhibits measurable width statistics and persistence distributions whose form depends on
turbulence strength and source-plane beam size. This object-level framework remains well-defined within the regime of strong
turbulence and provides a complementary approach to characterizing turbulent propagation beyond conventional ensemble-averaged metrics.
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Optics · Cross-listed from cond-mat.mtrl-sci
Optically Active Fractional Wannier-Center Displacement Drives Giant Second-Harmonic Generation
Hongsheng Pang and Lixin He
Electric polarization is a static ground-state Berry-phase property, whereas second-harmonic generation (SHG) and shift current are dynamical optical responses. Their connection is encoded in the shift vector, whose Brillouin-zone average is governed by the band-resolved Berry-phase polarization difference between the optically connected initial and final states. Here we exploit this
geometric relation in quantized formal polarization (QFP)
crystals, where
symmetry-quantized formal-polarization branches correspond to fractional Wannier-center sectors. First-principles screening identifies noncentrosymmetric QFP materials with
giant SHG responses, including $\mathrm{InNbBr}_6$ and $\mathrm{InPS}_3$. Band-resolved Berry-phase analysis shows that their dominant optical transitions connect occupied and low-lying unoccupied states whose Wannier centers lie at distinct fractional Wyckoff positions, producing a large transition-resolved Wannier-center displacement. This displacement gives rise to a large shift vector and a dominant shift-vector-related intraband contribution to the static SHG susceptibility. Our results show that
symmetry-quantized formal polarization can become optically active through transitions between fractional Wannier-center sectors, providing a
symmetry-guided route to
giant SHG and shift-current responses.
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Space Physics
Direct Observations of Magnetic Reconnection in the Solar Wind Current Sheets near Mars
Chi Zhang, Chuanfei Dong, Xinmin Li et al. (+10 more)
Magnetic reconnection is a fundamental and ubiquitous process in astrophysical
plasmas that converts
magnetic energy into
plasma kinetic and thermal energy. Throughout the heliosphere, the
solar wind is permeated with current sheets (CSs), providing a natural laboratory for investigating this process. Using measurements from NASA's Mars Atmosphere and Volatile
EvolutioN (MAVEN) spacecraft, we report the first direct observations of
magnetic reconnection occurring within the
solar wind CSs near Mars. Specifically, MAVEN observed the classic Petschek-type reconnection exhaust regions, evidenced by bifurcated
magnetic field signatures and Alfvenic ion
outflows. Notably, the observed exhaust region appears to be large-scale, significantly exceeding the typical thickness of
solar wind CSs near Mars. This suggests that
magnetic reconnection may significantly broaden the CS. Our results underscore the ubiquity of
magnetic reconnection across heliocentric distances and may provide new insights into the large-scale
evolution of the
solar wind and the development of
turbulence within it.
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All authors Chi Zhang, Chuanfei Dong, Xinmin Li, Han-Wen Shen, Jasper Halekas, Tai Phan, Christian Mazelle, Yuki Harada, Hongyang Zhou, Jiawei Gao, Liang Wang, Shannon Curry, David L. Mitchell
Optics
Optimization of photonic waveguide bends for low index contrast material platforms
Ritu Jangra, Kushagra Agarwal, Posa Harsha Vardhan et al. (+2 more)
Compact and low loss waveguide bends are vital for enhancing the integration density of on chip photonic devices. The bend loss becomes extremely critical, particularly for compact bends in low index contrast platforms such as Indium Phosphide. To address this issue, we introduce an elliptical width modulated bend, which exhibits low loss. For example, at 6 micrometers radius bend loss for elliptical width modulated bend is 0.22 decibels per 90 degrees, resulting in about 40 percent and 27 per cent reduction compared to conventional circular bends and circular width modulated bends, respectively with only a 15 per cent increase in footprint providing a better loss area trade off. Additionally, conventional effective index based analytical models do not account for the impact of width modulation. In this work, we develop an enhanced analytical bend loss formulation that incorporates these effects and validates its accuracy through close agreement with full three dimensional Finite Difference Time Domain simulations.
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All authors Ritu Jangra, Kushagra Agarwal, Posa Harsha Vardhan, Nandana P K, Naresh Kumar Emani
Optics
Mid-infrared snapshot spectral imaging via nonlinear radial dispersion
Jianan Fang, Kun Huang, Ruiyang Qin et al. (+2 more)
Mid-infrared (MIR) spectral imaging provides chemically specific contrast through molecular vibrational fingerprints, yet snapshot acquisition remains severely limited by the lack of high-sensitivity detectors and efficient spectral encoding mechanisms. Here we introduce snapshot MIR spectral imaging based on intrinsic nonlinear radial dispersion, in which wavelength-dependent phase matching simultaneously enables frequency upconversion and spectral multiplexing. Different spectral components are mapped to distinct output angles within a 4$f$ imaging architecture, enabling single-shot spectral encoding without external dispersive elements. In combination with speckle illumination encoding, spectral information is compressed and recovered without additional coding components. Leveraging nonlinear upconversion to the visible, the approach achieves room-temperature MIR spectral imaging with sensitivity approaching 1
photon/pixel/pulse across a broad spectral range from 2.5 to 4.0 $\mu$m. This work transforms spectral encoding from an external optical function into an inherent property of the nonlinear imaging process, providing a general route to high-sensitivity snapshot MIR spectral imaging.
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All authors Jianan Fang, Kun Huang, Ruiyang Qin, Jixi Zhang, Heping Zeng
Optics
Integrated Terahertz Photonic Receiving Frontend with Link Noise Outperforming Electronics
Yuansong Zeng, Zixi Wang, Liga Bai et al. (+13 more)
Terahertz technology is a key enabler for sixth-generation (6G) wireless networks, yet its application is constrained by increasingly severe free-space loss at high frequencies. To efficiently retrieve weak signals at the receiving end, a compact frontend that features both a high-gain
antenna and a low-noise signal-detection chain is critical. Current transistor-based THz electronic frontends face significant challenges in meeting these demands because both on-chip
antenna efficiency and transistor noise performance degrade rapidly when approaching their cut-off frequencies. Photonic technology provides an alternative solution to circumvent the transistor bandwidth limit, yet most microwave photonic links to date exhibit noise performance substantially worse than state-of-the-art electronics. Here, we demonstrate low-noise integrated THz photonic frontends that deliver undegraded link noise performance across three major THz windows from 140 to 450 GHz, and outperform electronic frontends in the upper two windows. We achieve this through co-design of high-gain on-chip THz
antenna array and broadband THz-optic modulator on a single thin-film lithium niobate (TFLN) chip, leading to distributed reception of free-space THz signals and continuous coherent build-up of the THz-optic conversion process with unprecedented efficiency. Combined with an efficient heterodyne detection chain, our integrated frontends exhibit effective isotropic noise figures of 13.6 and 16.2 dB at 250 and 450 GHz, respectively, both setting new
benchmarks in their respective bands. We further demonstrate 6G-oriented multi-link communication up to 20 Git/s. Our integrated frontends represent a significant step towards compact, cost-effective and energy-efficient THz wireless systems in 6G and beyond.
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All authors Yuansong Zeng, Zixi Wang, Liga Bai, Yuansheng Tao, Yiwen Zhang, Yifan Wu, Zhe Ding, Xiangzhi Xie, Zhaoxi Chen, Lu Zhang, Shi-Wei Qu, Jun Hu, Hanke Feng, Chi Hou Chan, Xianbin Yu, Cheng Wang