http://rss.arxiv.org/rss/physics.app-ph physics.app-ph updates on the arXiv.org e-print archive. http://www.rssboard.org/rss-specification en-us Wed, 10 Jun 2026 04:00:28 +0000 rss-help@arxiv.org Wed, 10 Jun 2026 00:00:00 -0400 Sunday Saturday https://arxiv.org/abs/2606.10236 arXiv:2606.10236v1 Announce Type: new Abstract: Photodiodes based on trap-assisted current injection can exhibit internal photomultiplication with apparent quantum efficiencies far exceeding unity, raising the question of whether such gain fundamentally enhances detector sensitivity. We employ a minimal analytical framework based on a single gain-active trapped state coupling photogenerated carriers to contact injection. The gain is intrinsically self-limiting: the injection process that amplifies the current simultaneously accelerates relaxation of the gain-enabling state, producing an inherently nonlinear, operating-point-dependent response. The form of this nonlinearity is not universal -- once the trap level is generalized to an energetic distribution and recombination is allowed to be bimolecular, the same mechanism yields superlinear, linear, or strongly sublinear responses. A single chord gain is therefore not a meaningful device descriptor, and chord-gain comparisons across the literature conflate devices in different regimes. Treating trap occupancy and injection as coupled stochastic processes, we show that internal gain introduces a strictly non-negative fluctuation penalty from the dissipative dynamics that sustain the gain state. A local, small-signal detectivity exhibits a finite optimum yet cannot exceed the intrinsic thermodynamic limit of the underlying unity-gain photodiode. Gain is thus equivalent to driven stochastic amplification: it can suppress downstream readout noise, but cannot reduce the fundamental noise floor set by the primary photodetection process. oai:arXiv.org:2606.10236v1 physics.app-ph Wed, 10 Jun 2026 00:00:00 -0400 new http://creativecommons.org/licenses/by/4.0/ Ardalan Armin https://arxiv.org/abs/2606.10262 arXiv:2606.10262v1 Announce Type: new Abstract: We performed a 2D finite-element electrothermal computational study of thermoelectric effects and filamentary electronic transport in Ge$_2$Sb$_2$Te$_5$ mushroom phase change memory cells during Reset and Set operations, accounting for spatial activation energy variations in amorphous Ge$_2$Sb$_2$Te$_5$ and phase-change dynamics. Reset operations with current going from the top electrode to the narrow 4 nm bottom electrode require $\sim$3x less energy and power, and $\sim$2x lower current to achieve the same Reset resistance, compared to the opposite polarity, due to thermoelectric effects. Filamentary conduction, electrical breakdown, thermal runaway, and local crystallization of amorphous Ge$_2$Sb$_2$Te$_5$ depend on current polarity and thermal boundary conditions, and determine the location, shape, and volume of the programming region, which may be significantly smaller than the semi-cylindrical mushroom region. The programming volume does not scale with contact dimensions larger than 10 nm. Larger contact areas introduce increased device-to-device and cycle-to-cycle variability due to filamentary conduction but are expected to lead to higher reliability and endurance. oai:arXiv.org:2606.10262v1 physics.app-ph cond-mat.mtrl-sci Wed, 10 Jun 2026 00:00:00 -0400 new http://creativecommons.org/licenses/by/4.0/ Md Samzid Bin Hafiz, Helena Silva, Ali Gokirmak https://arxiv.org/abs/2606.10269 arXiv:2606.10269v1 Announce Type: new Abstract: In this work, we investigate the response of Ni/$\beta$-Ga$_2$O$_3$ Schottky barrier diodes fabricated on c-plane sapphire to fast-neutron irradiation up to a fluence of $1\times10^{15}$ n$\cdot$cm$^{-2}$. The LPCVD-grown heteroepitaxial structure consists of an unintentionally doped buffer, an n$^{+}$ contact layer, and an n-type drift layer, with mesa isolation realized by plasma-free Ga-assisted LPCVD etching. Prior to irradiation, the devices exhibit a turn-on voltage of 1.20 V, specific on-resistance of 8.43 m$\Omega\cdot$cm$^2$, ideality factor of 1.32, and Schottky barrier height of 1.29 eV. Following irradiation, the devices remain operational, although the forward current decreases, the turn-on voltage increases to 2.40 V, and the barrier height increases to 1.34 eV. Capacitance-voltage measurements reveal a $\sim$50% reduction in net donor concentration, corresponding to a carrier-removal rate of $\sim$105 cm$^{-1}$. Temperature-dependent measurements from 25 to 250 $^\circ$C confirm that thermionic emission remains the dominant transport mechanism and show significant suppression of reverse leakage current after irradiation. The breakdown voltage increases from 101 to 135 V, consistent with neutron-induced donor compensation. TCAD simulations show a more uniform electric-field distribution and reduced field crowding at the Schottky edge after irradiation. These results provide insight into neutron-induced donor compensation in heteroepitaxial $\beta$-Ga$_2$O$_3$ and demonstrate the ability of LPCVD-grown $\beta$-Ga$_2$O$_3$ Schottky diodes on sapphire to maintain stable operation under high-fluence neutron environments relevant to space and nuclear electronics. oai:arXiv.org:2606.10269v1 physics.app-ph Wed, 10 Jun 2026 00:00:00 -0400 new http://arxiv.org/licenses/nonexclusive-distrib/1.0/ Saleh Ahmed Khan, Ahmed Ibreljic, Sourav Sarker, Stephen Margiotta, Anhar Bhuiyan https://arxiv.org/abs/2606.10437 arXiv:2606.10437v1 Announce Type: new Abstract: The dynamics of rolling tires significantly influence the low-frequency (0-500 Hz) structure-borne noise within vehicles. Accurately characterizing these dynamics under realistic operating conditions remains challenging. Current state-of-the-art methods, primarily relying on Laser Doppler Vibrometers (LDV), are complex to implement, time-intensive, and generally limited to smooth tires in laboratory environments due to issues with speckle formation on treaded surfaces. This study introduces an innovative strategy for Operational Modal Analysis (OMA) of a rolling tire using a single wireless Tire Cavity Accelerometer (TCA) together with two optical sensors. The methodology leverages the non-integer ratio between the tire and drum diameters in a test rig to create a virtual sensor array. By utilizing optical sensors to time-stamp the cleat impact (on the drum) precisely and the TCA position (on the tire), the vibration responses from multiple revolutions are clustered according to the TCA's circumferential position at the moment of impact. This effectively synthesizes responses from an array of virtual sensors distributed around the tire circumference using data from a single test run. The clustered signals are conditioned using order tracking to remove periodic components arising from contact patch deformation. Both Frequency Domain Decomposition (FDD) and Covariance-based Stochastic Subspace Identification (SSI-Cov) were employed for modal identification. The SSI-Cov method proved more robust, successfully identifying 11 circumferential modes up to 240 Hz. The proposed approach offers a significantly more efficient, cost-effective method for characterizing rolling tire dynamics, which is readily applicable to treaded tires and adaptable for on-road testing. oai:arXiv.org:2606.10437v1 physics.app-ph physics.data-an Wed, 10 Jun 2026 00:00:00 -0400 new http://arxiv.org/licenses/nonexclusive-distrib/1.0/ Pradosh Pritam Dash, Ricardo Burdisso, Pablo A Tarazaga https://arxiv.org/abs/2606.10221 arXiv:2606.10221v1 Announce Type: cross Abstract: Interpreting metal K-edge spectra of flexible photosensitizers requires a structural model that separates electronic signatures from thermal motion, solvent disorder, and crystal-packing effects. We combine Fe K-edge X-ray absorption measurements with second-generation Car--Parrinello ab initio molecular dynamics and all-electron Gaussian and augmented-plane-wave simulations for an iron(II) N-heterocyclic carbene photosensitizer in acetonitrile solution and in the crystalline phase. Ensemble-averaged spectra reproduce the main near-edge features in both environments and preserve the experimentally observed similarity of the first Fe coordination shell upon dissolution. Comparison with radial distributions extracted from extended fine-structure measurements validates the Fe--N and Fe--C coordination shells sampled by the trajectories, while element-resolved pair distributions explain why higher-shell experimental contrast is rapidly lost. The same dynamical ensembles reveal a broad out-of-plane distribution of the terpyridine nitrogen atom and a nearly octahedral distribution of the Fe-centered coordination planes. The results show that finite-temperature X-ray absorption simulations can provide a compact structural-dynamics picture of molecular transition metal photosensitizers by linking local spectra, solvent-phase ligand motion, and medium-range structural disorder within one trajectory-based description. oai:arXiv.org:2606.10221v1 cond-mat.mtrl-sci physics.app-ph physics.chem-ph physics.comp-ph Wed, 10 Jun 2026 00:00:00 -0400 cross http://arxiv.org/licenses/nonexclusive-distrib/1.0/ Patrick M\"uller, Lorena Fritsch, Matthias Bauer, Thomas D. K\"uhne https://arxiv.org/abs/2606.10253 arXiv:2606.10253v1 Announce Type: cross Abstract: Spatial multiplexing is one of the natural strengths of optics, yet in optical neural networks, it is often used mainly as parallel throughput. Here, we show that spatial multiplexing in an optical neural network can be used not only to process multiple inputs in parallel, but also to define a trainable representational coordinate of the model. In three implemented scenarios, parallel-input processing, class-code readout and channel-mixed feature interaction, spatial channels act as independent learners, structured code dimensions, and interacting feature groups. The programmable free-space optical processor is trained through an online physical-forward/surrogate-backward scheme, where measured optical outputs define the forward pass while a differentiable surrogate estimates gradients and is continually fine-tuned during training from newly acquired optical data. We demonstrate these channel roles in image classification and regression tasks using multi-layer architectures with more than one million trainable optical phase parameters. We further implement a hybrid optical-electronic vision-language model, in which the optical neural network provides visual tokens to a digital transformer decoder for controlled image-captioning tasks. These results establish spatially multiplexed optical channels as a programmable feature and readout space for hybrid optical vision models. oai:arXiv.org:2606.10253v1 physics.optics physics.app-ph Wed, 10 Jun 2026 00:00:00 -0400 cross http://arxiv.org/licenses/nonexclusive-distrib/1.0/ Ali Momeni, Guillaume Noetinger, Tim Tuuva, Romain Fleury https://arxiv.org/abs/2606.10755 arXiv:2606.10755v1 Announce Type: cross Abstract: Evaporating sessile droplets are usually treated as capillary objects, but droplets generated by routine handling can carry tens to hundreds of picocoulombs of electric charge. Here we combine Faraday-cup charge measurements with optical imaging to determine how such charge evolves as water droplets evaporate on dry polymer substrates. A zero-time protocol shows that a reproducible initial charge is preserved on poly(methylpentene) (PMP), whereas PDMS, SOCAL-coated surfaces, and polystyrene either exchange, dissipate, or inject charge on contact. On PMP, ensemble-resolved measurements reveal two regimes: the charge remains nearly constant during early evaporation and then decreases abruptly once the droplet reaches a small-volume state. This charge collapse coincides with spontaneous lateral translation rather than jetting or breakup. A Rayleigh-normalized analysis, including a spherical-cap stress correction and measured contact-angle retention scale, shows that motion occurs only after evaporation drives the droplet into a high electro-pinning state. High-speed imaging and kinematic analysis support a picture in which the subsequent motion is governed by repeated contact-line depinning and re-pinning: the total distance traveled is strongly affected by dry-surface pinning, whereas the peak translational velocity serves as a more robust indicator of the discharge strength. These results identify a dry-substrate mode of evaporation-driven electrostatic relaxation, distinct from Coulomb fission on lubricated surfaces, in which substrate electrostatic passivity enables charge retention, droplet geometry selects the instability onset, and whole-droplet translation provides the charge-release pathway. oai:arXiv.org:2606.10755v1 cond-mat.soft physics.app-ph Wed, 10 Jun 2026 00:00:00 -0400 cross http://creativecommons.org/licenses/by-nc-nd/4.0/ Riming Xu, Yanbo Li, Jiawen Zhang, Jin Wang, Yikai Li https://arxiv.org/abs/2605.00290 arXiv:2605.00290v2 Announce Type: replace Abstract: Integrated circuits are a cornerstone of modern information technology, and analog wave-based architectures could enable fast and efficient processing beyond conventional charge electronics. In magnonics, spin waves provide a highly tunable, compact and energy-efficient medium for on-chip microwave signal transport and processing. However, progress has been limited to isolated elements or short devices, severely limiting the overall functional complexity and scalability. Here we realize the key elements of universal magnonic circuitry, using a single-step direct laser writing process in yttrium iron garnet, and monolithically cascade them in multi-stage programmable devices and networks. Using magneto-optical Kerr effect microscopy, we show efficient spin-wave propagation and preserved phase coherence in waveguide structures for hundreds of wavelengths. In coupled waveguides, we observe complete and periodic power transfer over several coupling lengths, and in phase shifters we achieve arbitrary, tunable phase delays. By cascading these elements, we realize programmable splitters, frequency demultiplexers, and phase-controlled 2x2 routers, where output power and relative phase can be programmed on demand via external fields. Finally, we realize programmable magnonic interferometric meshes for on-chip radio-frequency signal routing, with up to six magnonic inputs and outputs and seven cascaded stages, without the need for intermediate amplification. These direct-write cascaded networks bridge a long-standing gap in magnonic scalability, offering a viable pathway toward integrated, large-scale architectures for both classical and quantum processing. oai:arXiv.org:2605.00290v2 physics.app-ph cond-mat.mtrl-sci Wed, 10 Jun 2026 00:00:00 -0400 replace http://creativecommons.org/licenses/by/4.0/ Piero Florio, Matteo Vitali, Valerio Levati, Rasheed M. Ishola, Luca Ciaccarini Mavilla, Nora Lecis, Carsten Dubs, Riccardo Bertacco, Marco Madami, Silvia Tacchi, Daniela Petti, Edoardo Albisetti https://arxiv.org/abs/2501.04339 arXiv:2501.04339v2 Announce Type: replace-cross Abstract: We introduce the Deep Convolutional Interpreter for Time Series (DCIts), a deep-learning architecture for nonlinear multivariate time series that provides sample-specific, locally interpretable descriptions of the underlying interaction structure. Unlike standard black-box forecasters, DCIts learns a time- and lag-dependent transition tensor explicitly factorized into two components: a Focuser, which selects relevant source series and time lags via a sparse masking mechanism, and a Modeler, which assigns signed coefficients to these selected interactions. This decomposition yields a local lag-adjacency structure and signed source-lag contributions for every forecast instance, enabling direct inspection of effective connectivity; when higher-order branches are activated, the same framework yields order-resolved elementwise polynomial contributions. Architecturally, DCIts uses a diverse bank of convolutional filters to capture temporal and cross-variable dependencies, which are mapped through a bottleneck network to the transition tensor. On controlled benchmark datasets with a known interaction structure, we demonstrate that DCIts achieves competitive forecasting error relative to a strong interpretable baseline while recovering stable, signed, lag-resolved interaction patterns. The framework thus prioritizes intrinsic interpretability, using forecasting accuracy as a faithfulness constraint rather than the sole objective. oai:arXiv.org:2501.04339v2 stat.ML cs.LG physics.app-ph Wed, 10 Jun 2026 00:00:00 -0400 replace-cross http://arxiv.org/licenses/nonexclusive-distrib/1.0/ 10.1063/5.0325209 Chaos 36, 063116 (2026) Domjan Baric, Davor Horvatic https://arxiv.org/abs/2509.12015 arXiv:2509.12015v2 Announce Type: replace-cross Abstract: We demonstrate a grazing-incidence x-ray platform that simultaneously records time-resolved grazing-incidence small-angle x-ray scattering (GISAXS) and grazing-incidence x-ray diffraction (GID) from a femtosecond laser-irradiated gold film above the melting threshold, with picosecond resolution at an x-ray free-electron laser (XFEL). By tuning the x-ray incidence angle, the probe depth is set to tens of nanometers, enabling depth-selective sensitivity to near-surface dynamics. GISAXS resolves ultrafast changes in surface nanomorphology (correlation length, roughness), while GID quantifies subsurface lattice compression, grain orientation, melting, and recrystallization. The approach overcomes photon-flux limitations of synchrotron grazing-incidence geometries and provides stringent, time-resolved benchmarks for complex theoretical models of ultrafast laser-matter interaction and warm dense matter. Looking ahead, the same depth-selective methodology is well suited to inertial confinement fusion (ICF): it can visualize buried-interface perturbations and interfacial thermal resistance on micron to sub-micron scales that affect instability seeding and burn propagation. oai:arXiv.org:2509.12015v2 physics.optics physics.app-ph physics.ins-det physics.plasm-ph Wed, 10 Jun 2026 00:00:00 -0400 replace-cross http://arxiv.org/licenses/nonexclusive-distrib/1.0/ 10.1107/S2052252526001727 IUCrJ Vol.13, Pages 249-259 (2026) Lisa Randolph, \"Ozg\"ul \"Ozt\"urk, Dmitriy Ksenzov, Lingen Huang, Thomas Kluge, S. V. Rahul, Victorien Bouffetier, Carsten Baehtz, Mohammadreza Banjafar, Erik Brambrink, Fabien Brieuc, Byoung Ick Cho, Sebastian G\"ode, Tobias Held, Hauke H\"oppner, Gerhard Jakob, Mathias Kl\"aui, Zuzana Kon\^opkov\'a, Changhoo Lee, Gyusang Lee, Mikako Makita, Mikhail Mishchenko, Mianzhen Mo, Pascal D. Ndione, Michael Paulus, Alexander Pelka, Franziska Paschke-Bruehl, Thomas R. Preston, Baerbel Rethfeld, Christian R\"odel, Michal \v{S}m\'id, Ling Wang, Sebastian T. Weber, Lennart Wollenweber, Jan-Patrick Schwinkendorf, Christian Gutt, Motoaki Nakatsutsumi https://arxiv.org/abs/2605.01469 arXiv:2605.01469v2 Announce Type: replace-cross Abstract: Nonlinear energy exchange between vibrational modes underlies phenomena ranging from internal resonance and wave mixing to frequency-comb generation, yet modal interactions are typically inferred from spectra rather than directly observed in space. Here, we image nonlinear modal energy routing in a nearly mirror-symmetric microelectromechanical resonator using phase-locked multi-harmonic stroboscopic interferometry. By reconstructing the spatial eigenmode content of individual harmonics, we show that harmonics generated by a driven mode can be carried by distinct spatial eigenmodes, directly resolving spatial pathways of nonlinear energy transfer. Our measurements further reveal that this modal routing persists away from integer frequency matching: in the off-resonant regime, generated harmonic components are dominated by eigenmodes sharing the driven mode's mirror parity, whereas spectrally closer opposite-parity modes remain strongly suppressed. A nonlinear modal framework based on geometric nonlinearity shows that the relevant cubic coupling coefficients factorize into symmetry-dependent modal-overlap integrals, identifying mirror parity as the selection rule for nonlinear modal interaction. This work identifies spatial symmetry as a design parameter for nonlinear energy routing and provides a route to symmetry-engineered control of energy flow in multimode nonlinear wave systems. oai:arXiv.org:2605.01469v2 physics.optics physics.app-ph Wed, 10 Jun 2026 00:00:00 -0400 replace-cross http://creativecommons.org/licenses/by-nc-nd/4.0/ Ya Zhang, Yuko Terasawa, Qian Liu, Shumpei Takenaka, Hua Li, Yutao Xu, Xueyong Wei, Kazuhiko Hirakawa https://arxiv.org/abs/2605.17402 arXiv:2605.17402v2 Announce Type: replace-cross Abstract: The elasticity of PDMS has played a central role in advancing important microfluidic technologies, ranging from early valves to sophisticated organ-on-a-chip systems. However, most deformable microfluidic devices are based on geometries that require complex multi-layer PDMS architectures and include thin membranes, leading to difficult microfabrication and poor stability. Recently, Jain, Belkadi et al. (Biofabrication 16.3 (2024): 035010) introduced a single-layer PDMS device in which a wide and long microfluidic channel was deformed by pressurizing two adjacent air chambers. While they demonstrated how the channel ceiling deformation can be leveraged to compress biological materials, it remains unknown how the device geometry influences this deformation. Here, a systematic numerical study is performed on 14,336 variants of this device, through which the height of the PDMS layer is identified as the main feature that determines the ceiling deformation. Three modes of channel deformation are identified as the geometry are varied: a U shape with a central minimum, a W shape with two minima and a central maximum, or an inverse U shape with an upward-bulging single maximum. The numerical results are validated in experiments that reproduce the three modes for the predicted geometries and demonstrate vertical ceiling deformations ranging from a few microns to the millimeter scale. The generality of this approach is demonstrated for two example applications: A fully closing single-layer microfluidic valve and an optical lens of controllable anisotropic magnification. This work leverages the rapid prototyping enabled by 3D printing or micro-milling to open new perspectives in microfluidic actuation. oai:arXiv.org:2605.17402v2 physics.flu-dyn physics.app-ph Wed, 10 Jun 2026 00:00:00 -0400 replace-cross http://creativecommons.org/licenses/by/4.0/ Leon V. Gebhard, Alexandre S. Avaro, Gabriel Amselem, Charles N. Baroud https://arxiv.org/abs/2605.30498 arXiv:2605.30498v2 Announce Type: replace-cross Abstract: Trapped neutral atoms are one of the leading platforms for quantum information technologies, in particular for quantum computing, but scaling them to array sizes needed for utility-scale quantum computing is a major engineering challenge. Here we review optical metasurfaces as an enabling technology that provides fine control over the phase, amplitude, and polarization of light, with pixel counts far exceeding what is available with spatial light modulators (SLMs) and other active devices. The large pixel counts have recently led to demonstrations of arrays of optical tweezers with hundreds of thousands of sites and arrays of optical bottle-beams with complex three-dimensional trapping profiles. The flexibility and scalability of optical metasurfaces provides a route towards miniaturized, integrated, and highly scalable atomic experiments and instruments. oai:arXiv.org:2605.30498v2 physics.optics physics.app-ph physics.atom-ph quant-ph Wed, 10 Jun 2026 00:00:00 -0400 replace-cross http://arxiv.org/licenses/nonexclusive-distrib/1.0/ Chengyu Fang, Minjeong Kim, Mark Saffman, Jennifer T. Choy, Mikhail Kats