Atomic Physics · Cross-listed from quant-ph
Simple broadband signal detection at the fundamental limit
Anthony M. Polloreno and Graeme Smith
Broadband detection of a weak oscillatory field with unknown carrier frequency underlies magnetometry,
axion searches and gravitational-wave sensing. We show that the Grover-like integration-time lower bound for this task is a
geometric corollary of an upper bound on the integrated
quantum Fisher information and present an all-analog protocol with near-optimal scaling.
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Physics and Society
Abundance and Economic diversity as a descriptor of cities' economic complexity
Marco A. Rosas Pulido, Roberto Murcio, Omar R. Vázquez et al. (+1 more)
Intricate interactions among firms, institutions, and spatial structures shape urban economic systems. In this study, we propose a framework based on three structural dimensions – abundance, diversity, and longevity (ADL) of economic units – as proxies of urban economic complexity and resilience. Using a decade of georeferenced firm-level data from Mexico City, we analyze the relationships among ADL variables using regression, spatial correlation, and time-series clustering. Our results reveal nonlinear dynamics across urban space, with powerlaw behavior in central zones and logarithmic saturation in peripheral areas, suggesting differentiated growth regimes. Notably, firm longevity modulates the relationship between abundance and diversity, particularly in periurban transition zones. These spatial patterns point to an emerging polycentric restructuring within a traditionally monocentric metropolis. By integrating economic complexity theory with spatial analysis, our approach provides a scalable method to assess the adaptive capacity of urban economies. This has implications for understanding informality, designing inclusive urban policies, and navigating structural transitions in rapidly urbanizing regions.
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All authors Marco A. Rosas Pulido, Roberto Murcio, Omar R. Vázquez, Carlos Gershenson
Physics and Society
Nonequilibrium phase transitions in a racism-spreading model with interaction-driven dynamics
Nuno Crokidakis and Lucas Sigaud
Racism remains a persistent societal issue, increasingly amplified by the structure and dynamics of online social networks. In this work, we propose a three-state compartmental model to study the spreading and suppression of racist content, drawing from epidemic-like dynamics and interaction-driven transitions. We analyze the model on fully-connected (homogeneous mixing) networks using a set of coupled differential equations, and on Barabási-Albert (BA) scale-free and Watts-Strogatz (WS) small-world networks through
agent-based simulations. The system exhibits three distinct stationary regimes: two racism-free absorbing states and one active phase with persistent racist content. We identify and characterize the phase transitions between these regimes, discuss the role of network
topology, and highlight the emergence of absorbing states. Our findings illustrate how statistical physics tools can help uncover the macroscopic consequences of microscopic social interactions in digital environments.
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Applied Physics
Hydrodynamic Behavior of Non-spherical Particles in Confined Vertical Flows: A Resolved CFD-DEM Study
Amiya Prakash Das, Shakti Swaroop Choudhury, Sujith Reddy Jaggannagari et al. (+4 more)
We investigate the sedimentation and vertical hydraulic transport of non-spherical polymetallic nodules (PMNs) using resolved computational fluid dynamics-discrete element method (CFD-DEM) with multisphere particles spanning $98 < Re_\text{p} < 2904$. Shape effects induce 1.8-2.0 times drag enhancement relative to volume-equivalent spheres, arising from 50% larger frontal areas and wake asymmetry, reducing terminal velocities by 27-29%. Vertical transport exhibits velocity-driven transitions from intermittent settling to stable convection, as demonstrated by residence-time and drag-force statistics. While PMNs exhibit enhanced rotational-translational coupling and broader force fluctuations, the regime progression qualitatively resembles that of volume-equivalent spherical particles. Drag variance
evolution reveals contrasting behavior: small particles $(d/D=0.082)$ show narrow distributions and wake suppression at higher velocities, while large particles $(d/D=0.22)$ exhibit non-monotonic variance. These findings elucidate shape-confinement interactions in vertical transport and establish bounds on the applicability of volume-equivalent spherical particles in reduced-order models.
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All authors Amiya Prakash Das, Shakti Swaroop Choudhury, Sujith Reddy Jaggannagari, Amudha Krishnan, Gopkumar Kuttikrishnan, Balaji Ramakrishnan, Ratna Kumar Annabattula
Optics
Widely tunable SNAP microresonators via translation of side-coupled optical fibers
Isha Sharma and Misha Sumetsky
We demonstrate free spectral range (FSR) tunable Surface Nanoscale Axial Photonics (SNAP) microresonators induced by side-coupled parallel optical fiber segments. By translating one segment relative to the other, we tune the coupling length from $900~\mu$m to $100~\mu$m and thereby tune the microresonator FSR from $5$ pm to $50$ pm, with an estimated precision of better than $0.003$ pm. The microresonator Q-factor exceeds $10^5$ and can potentially be significantly increased in a clean lab environment. Possible applications of the demonstrated device include miniature and low-loss tunable delay lines and optical frequency comb generators, as well as ultraprecise tunable optical sensors.
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Computational Physics · Cross-listed from cond-mat.mtrl-sci
Comparative Analysis of Plasticity-based GND Density Estimation Methods in Crystal Plasticity Finite Element Models
Michael Pilipchuk, Chaitali Patil and Veera Sundararaghavan
In
crystal plasticity finite element (CPFE) simulations, accurately quantifying geometrically necessary dislocations (GNDs) is critical for capturing strain gradients in polycrystals. We compare different methods for quantifying GNDs, all of which originate from the Nye tensor, which is computed as the curl of the plastic deformation gradient. The projection technique directly decomposes the Nye tensor onto individual screw and edge dislocation components to compute GNDs. This approach requires converting a nine-component Nye tensor into densities for a larger number of dislocation systems, a fundamentally underdetermined (non-unique) process, which is resolved using $L2$ minimization. In contrast, when employing CPFE analysis, one could directly compute dislocation densities on each slip system using shear gradients. Projection and slip gradient methods are compared with respect to their prediction of GNDs with changing grain size, strain, and grain neighborhoods, including multigrain junctions. Although these techniques match analytical GND densities for single slip, single
crystal deformation, and are consistent with anticipated overall GND trends, we find that the GND densities from projection techniques are significantly lower than those predicted from CPFE-based slip gradients in polycrystals. A suggested improvement of only using the active dislocation systems in the projection technique almost entirely resolved this mismatch.
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Optics
6-mJ, 4-ns Pulse Generation at 2.09 $\mu$m from a Diode-Pumped Ho:YAG Thin-Disk Laser
Y. Koshiba, J. Mužík, M. Smrž et al. (+4 more)
A holmium-doped yttrium aluminum garnet (Ho:YAG) thin-disk was experimentally investigated under Q-switching and cavity-dumping operation schemes, pumped by a 1.9 $\mu$m
laser-diode (LD). The
laser generated pulses at 2090 nm with energies more than 6 mJ and pulse duration down to 3.8 ns, corresponding to a peak power of 1.6 MW with near-diffraction-limited beam quality. The compact and robust system was used for
laser-induced breakdown spectroscopy (LIBS) experiments, demonstrating its practical usability. These results represent, to the best of our knowledge, the first demonstration of a Ho:YAG thin-disk
laser providing MW peak-power in nanosecond regime.
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All authors Y. Koshiba, J. Mužík, M. Smrž, M. Dvořák, S. Kudělková, A. Fajstavr, Tomáš Mocek
Optics
Thermo-optic modulator with ultra-high extinction ratio for low-loss silicon nitride integrated photonics
Dmitriy Serkin, Kirill Buzaverov, Aleksandr Baburin et al. (+9 more)
Extremely low-loss silicon nitride integrated
circuits is a potential platform for a growing number of frontier applications in
quantum technologies, high-performance and analog computing, nonlinear optics, light detection and ranging (
LiDAR), and biotechnologies. However, efficient optical modulation with a wide frequency response, high contrast, low power and scalable manufacturing remains one of the key challenges for silicon nitride integrated photonics. Here, we propose an integrated thermo-optic phase shifter with isolation trenches operating in the C-band. The fabricated thermo-optic modulator capable to achieve a $\pi$-phase shift shift at a power consumption of 65 mW, bandwidth of 12 kHz, and extinction ratio (ER) over 80 dB. Moreover, we systematically demonstrate its compatibility with low-loss silicon nitride photonic integrated
circuits with microring resonators exibiting an average quality factor more than $5.9 \times 10^{6}$, which correspond to propagation loss of 0.058 dB/cm.
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All authors Dmitriy Serkin, Kirill Buzaverov, Aleksandr Baburin, Evgeny Sergeev, Sergey Avdeev, Evgeniy Lotkov, Sergey Bukatin, Ilya Stepanov, Aleksey Kramarenko, Ali Amiraslanov, Ilya Ryzhikov, Ilya Rodionov
Applied Physics · Cross-listed from quant-ph
Optimally Driven Dressed Qubits
Alon Salhov, Sagi Nechushtan and Alex Retzker
The applicability and performance of
qubits dressed by classical fields are limited because their control protocols give rise to an undesired counter-rotating term (CRT). This in turn forces operation in a regime where a (dressed) rotating-wave approximation (RWA) is valid, thereby restricting key aspects of their operation. Here, using only a single coupling axis in the laboratory frame, we introduce a dressed-
qubit control protocol that optimally removes the CRT, eliminating the need for the RWA and delivering substantial improvements in multiple performance metrics, including single-
qubit gate speed, two-
qubit gate fidelity, spectroscopic range, clock stability, and coherence preservation. In addition, we provide a general parameterization together with a Floquet-based coherence-time expression, which elucidates the protocol's working principles and lowers the barrier to adoption. Collectively, these advances position our scheme as the state-of-the-art strategy for
qubit control, paving the way for a wider class of
quantum technologies to be realized using dressed-
qubit architectures.
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Chemical Physics
Orthogonally Constrained CASSCF Framework: Newton-Raphson Orbital Optimization and Nuclear Gradients
Loris Delafosse, Vincent Robert and Saad Yalouz
In a recent work, we introduced the foundations of an orthogonally constrained complete active space self-consistent field (OC-CASSCF) framework that produces state-specific molecular orbitals for mutually orthogonal multiconfigurational electronic states. In the present study, we extend this approach by incorporating a Newton-Raphson orbital-optimization scheme, for which we derive analytical expressions of the orbital gradient and Hessian. Furthermore, we outline a practical route toward the evaluation of analytical
nuclear gradients, enabling geometry optimizations within the OC-CASSCF formalism.
Benchmark calculations on the three lowest singlet states of LiH and H$_2$O molecules demonstrate a systematic improvement as compared to conventional state-averaged CASSCF, even when using modestly sized active spaces.
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Chemical Physics
Locally Scaled Self-Interaction Corrected Energy Functionals with Complex Optimal Orbitals
Jukka John, Hlynur Gu{\dh}mundsson, I{\dh}unn Björg Arnaldsdóttir et al. (+2 more)
We present a fully variational locally scaled self-interaction corrected (SIC) energy functional using complex optimal orbitals. This represents an important milestone for fully variational SIC energy functionals, which have been shown to improve the prediction of the properties of atomic, molecular and solid state systems in general, in both ground and excited states. However, it depends on the system and property of the system whether it is beneficial to scale the SIC correction by a factor of one-half, which makes the application of SIC inconsistent. In the limit of a single electron the SIC exactly cancels the self interaction error, but overcorrects the error in regions of high density where there is large overlap between occupied orbitals. The newly implemented local scaling function, $z(\mathbf{r})$, which is based on an iso-orbital indicator derived from considering the kinetic energy density in the iso-electron and many electron case, and takes into account that the orbitals are complex, naturally scales the SIC correction from $0\leq z(\mathbf{r}) \leq 1$ in regions of high and low (isolated orbital) electron density. The locally scaled and fully variational SIC framework is general and applicable to atomic, molecular and solid-state systems.
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All authors Jukka John, Hlynur Gu{\dh}mundsson, I{\dh}unn Björg Arnaldsdóttir, Hannes Jónsson, Elvar Örn Jónsson
Optics
Optical steering of a large ring laser
Jannik Zenner, Karl Ulrich Schreiber and Simon Stellmer
A common approach to reduce the linewidth of a
laser is an increase of its resonator length. In large gas
lasers, however, the frequency spacing between longitudinal modes of the resonator easily becomes significantly smaller than the Doppler-broadened width of the gain profile. As a consequence, the
laser might operate on a multitude of modes simultaneously, or jump between modes. Such unstable operation cannot be tolerated in metrological or sensing applications, such as ring
laser gyroscopes. Here, we propose and demonstrate a method to establish stable operation on a chosen mode index by optically steering the ring
laser to a desired mode index through injection locking with an external
laser. The injected mode reliably follows the external steering. Intra-cavity backscattering can even cause the counter-propagating, non-injected mode to follow the external steering as well.
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Optics
Microring Resonator Dispersion Metrology with Neural Networks
Ergun Simsek, Shao-Chien Ou, Gregory Moille et al. (+1 more)
Precise knowledge of resonator dispersion, from both
geometric and material contributions, is essential for reliable high-performance nonlinear integrated photonics devices, such as optical parametric oscillators, frequency doublers, and integrated optical frequency combs. However, direct measurements at the fabrication level provide limited knowledge, whether through destructive cross-section imaging or non-destructive ellipsometry, while complete optical characterization that enables precise dispersion metrology is time-consuming and poorly suited for mass-scale foundry fabrication. In this work, we develop a machine learning framework to solve three complementary problems: (i) predicting resonator
geometric dimensions, (ii) identifying the correct material dispersion, and last, but not least, (iii) precisely reconstructing the integrated dispersion spectrum directly from ring dimensions. These three neural networks together enable both inverse and forward characterization of microring resonators. Using numerically generated
datasets based on Sellmeier-type material models, we demonstrate <1 nm ring dimension prediction accuracy without noise, <8 nm prediction accuracy with ~45 dispersion samples under a realistic frequency measurement noise level (50 MHz), and ~16 nm prediction accuracy at a higher noise level (200 MHz). The Sellmeier model classification exceeds 99% accuracy in all cases. Importantly, dispersion sampled far from the pump resonances proves most informative, reducing full-spectrum characterization requirements. The forward-prediction network reconstructs dispersion spectra from the ring dimensions with high accuracy. Our results highlight the potential of machine learning applied to dispersion data as a rapid, non-destructive tool for wafer-scale quality control and process monitoring in photonic foundries.
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All authors Ergun Simsek, Shao-Chien Ou, Gregory Moille, Kartik Srinivasan
Chemical Physics · Cross-listed from quant-ph
Efficient Application of Tensor Network Operators to Tensor Network States Through Successive Deterministic Compression
Richard M. Milbradt, Shuo Sun, Christian B. Mendl et al. (+2 more)
We introduce an
algorithm to apply tree tensor network operators to tree tensor network states followed by compression. Especially when applying a
matrix product operator to
matrix product states, this serves as a key subroutine in tensor network
algorithms. We name the method successive deterministic compression (SDC). We compare SDC to existing operator application and compression
algorithms in
benchmarks involving random tensor network operators and states, as well as
circuit simulation with standard entangling gates. We find that successive deterministic compression is consistently among the best-performing techniques when the tensor network state (after the operator application) is not highly compressible. Our results also highlight the flexibility of general tree tensor network structures for simulating
circuits with long-range
entanglement.
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All authors Richard M. Milbradt, Shuo Sun, Christian B. Mendl, Johnnie Gray, Garnet K.-L. Chan
Optics
Design Principles for Tailoring Heat Transport via Iris-Gated Core-Double-Shell Nanoparticles in the Context of Photothermal Therapies
Javier González-Colsa, Fernando Bresme and Pablo Albella
The rational design of Janus nanostructures that combine efficient optical absorption with controlled thermal transport is essential for advancing plasmonic photothermal therapies and related applications. Here, we introduce a theoretical and computational framework to investigate core-double-shell nanoparticles and their asymmetric version, the iris-gated core-double-shell architecture. The optical response of the structures is first evaluated using generalized Mie theory and subsequently validated through FEM and FDTD simulations, ensuring a consistent description of their electromagnetic and thermal behavior. To systematically map the space of variables, we defined a multi-objective figure of merit that integrates absorption efficiency, absorption cross section, and
polymer-layer thickness. Furthermore, we define a thermal gain parameter that quantifies energy densification and complements the analysis of thermal directionality. Our results reveal a near-optimal configuration with parameters ($r_c$, $\delta_{Au}$, $\delta_p$, $\theta$)=(36 nm, 5 nm, 40 nm, 70$\deg$), capable of producing a temperature rise of 20-23 $\deg$C, with 67% of the thermal fluz directed toward the upper hemispace and yielding 50% focusing enhancement relative to the symmetric case. This design preserves
geometric simplicity and high
symmetry while delivering robust thermal asymmetry, thereby facilitating experimental implementation. Beyond photothermal therapies, the proposed methodology constitutes a versatile platform for the rapid screening and optimization of layered nanostructures, adaptable to diverse materials, excitation wavelengths, and functional objectives in nanophotonics.
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Optics
Self-locking non-volatile coding metasurfaces via origami-based mechanical bits
Ding Zhang, Peng Tang, Liqiao Jing et al. (+7 more)
Digital coding metasurfaces have revolutionized electromagnetic (EM) manipulation, yet typical tunable approaches based on active components suffer from the "
volatility" bottleneck. While mechanical modulation provides a potential solution, current implementations generally lack inherent state-locking capability, rendering them vulnerable to environmental disturbances and actuation errors. Inspired by the concept of mechanical bits (MBs), this paper presents a self-locking non-volatile coding metasurface platform enabled by Kresling origami-based MBs, where the continuous mechanical deformation of individual meta-atoms is discretized into robust binary
geometric states protected by intrinsic energy barriers. The bistable states are strictly mapped to 1-bit EM coding phases via tailored metallic patterns integrated onto a multimaterial 3D printed Kresling origami array. Building upon this concept, both transmission- and reflection-type prototypes are proposed and experimentally demonstrated, exhibiting exceptional wavefront manipulation capabilities through near-field
holographic imaging and far-field beam steering. In addition, the lightweight origami unit (1.5 g) exhibits an exceptional load-bearing capacity, supporting over 100 times its own weight. These results bridge mechanical logic with EM information processing, establishing a universal physical paradigm for constructing low-power, highly robust coding metasurfaces resilient to extreme environments.
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All authors Ding Zhang, Peng Tang, Liqiao Jing, Xincheng Yao, Bo Zhou, Enzong Wu, Ying Li, Evgueni Filipov, Hongsheng Chen, Zuojia Wang
Fluid Dynamics
Unveiling crown-finger instability of a non-spherical drop impacting a liquid surface
Nagula Venkata Anirudh, Sachidananda Behera and Kirti Chandra Sahu
We present a three-dimensional numerical study of the splashing dynamics of non-spherical droplets impacting a quiescent
liquid film, covering a wide range of aspect ratios (Ar) and Weber numbers (We). The simulations reveal distinct impact dynamics, such as spreading, splashing type-1, splashing type-2, and canopy formation, which are delineated in a regime map constructed in the Ar-We parameter space. Our results demonstrate that droplet morphology during the impact significantly influences crown
evolution and splash initiation, with oblate drops promoting finger growth and fragmentation due to enhanced rim deceleration, while prolate drops tend to form canopies. We observe that the hole instability, which becomes more prominent at higher Weber numbers, arises from lamella rupture in the thinnest region of the film, located just beneath the crown rim. A linear stability analysis, supplemented by the temporal
evolution of the crown obtained from the numerical simulations, adequately predicts the number of fingers formed along the crown rim by accounting for both Rayleigh-Plateau (RP) and Rayleigh-Taylor (RT) instabilities. The theoretical analysis demonstrates the dominant role of the Rayleigh-Plateau instability in determining the number and wavelength of early undulations, with the Rayleigh-Taylor instability serving to amplify the growth rate of the disturbances. Our findings highlight the critical role of the droplet shape in splash dynamics, which is relevant to a range of applications involving droplet impact.
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Computational Physics · Cross-listed from astro-ph.HE
Rarity of rocket-driven Penrose extraction in Kerr spacetime
An T. Le
We study rocket-driven Penrose extraction in the test-particle limit on a fixed Kerr background for equatorial prograde flybys under explicit steering prescriptions. A spacecraft ejects exhaust inside the ergosphere; when the exhaust attains negative Killing energy, the remaining spacecraft gains energy by 4-momentum conservation. Across 320{,}000 simulated trajectories spanning black-hole
spin, exhaust velocity, and orbital parameters, extraction with escape is rare in broad parameter scans (at most ${\sim}1\%$) and requires high
spin ($a/M\gtrsim 0.89$), highly relativistic exhaust ($v_e\gtrsim 0.91c$), and finely tuned initial conditions. Under optimal tuning the success rate reaches ${\sim}70\%$ at $a/M = 0.95$. For representative escape trajectories, a single periapsis impulse is more propellant-efficient than the continuous-thrust controllers studied here. All quoted thresholds are empirical and specific to the orbit family, prior, and steering protocol studied.
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Fluid Dynamics
Investigating the mechanism by which finite-size heavy particles are entrained in turbulent open channel flow over a smooth surface
Tatia Bzikadze, Markus Weyrauch and Markus Uhlmann
The dynamics of entrainment of finite-size heavy particles in a turbulent open channel flow over a smooth surface are analyzed. Three types of simulations, namely with freely moving, rotation-constrained, and spanwise-motion-constrained particles, were conducted using particle-resolved direct numerical simulations. With the aid of a relative velocity suitably defined in the vicinity of the finite-size particle, we decompose the hydrodynamic force into drag and lift contributions and evaluate the local wall-normal shear rate around the particles. By means of coherent structure eduction techniques, we investigate flow structures before and during lift-off events. Rotation-constrained simulations revealed the insignificance of particle rotation in the entrainment mechanism. Spanwise-motion-constrained simulations revealed the importance of particle location with respect to flow structures with apparent changes in entrainment frequency, duration of the entrainment process, wall-normal shear around the particles, and distance to the nearest vortical structures during lift-off. The contribution of lift to the wall-normal force is found to be responsible for the initiation of particle entrainment, which is induced by a high-shear event associated with fast-moving fluid. The presence of quasi-streamwise
vortices is shown to be an important ingredient for the entrainment of particles into the bulk flow. The results show that, at marginal Shields number values, a high wall-normal shear rate and the proximity of an intense quasi-streamwise
vortex are essential elements of the entrainment mechanism.
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Applied Physics
Nonlocal Dual-Band Reconfigurable Intelligent Surfaces for Precise Full-Space Beamforming
Moosung Kim and Minseok Kim
This paper introduces a nonlocal, dual-band reconfigurable intelligent surface (RIS) designed for full-space beam synthesis at 4.0 GHz and 6.3 GHz. The constituent unit
cells comprise a pair of interleaved sub-
cells that are specifically engineered to operate independently at their respective target frequencies. This hardware-level decoupling facilitates an efficient synthesis framework based on microwave network theory (MNT) that rigorously accounts for mutual coupling within both bands. Under this framework, the optimal biasing for sub-
cells is determined to achieve precise full-space beam synthesis at both frequencies. The proposed method is numerically and experimentally validated with an RIS comprising 14 X 14 varactor-loaded unit
cells that can be individually biased. We experimentally demonstrate arbitrary beam profile synthesis beyond simple beam steering, including dual-beam and sector patterns in full space. Experimental and simulation results show good agreement with the MNT model, confirming the effectiveness of the proposed method.
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Fluid Dynamics · Cross-listed from astro-ph.EP
Beyond solar metallicity: How enhanced solid content in disks re-shape low-mass planet torques
Zs. Regaly and A. Nemeth
The migration of low-mass
planets is tightly controlled by the torques exerted by both gas and solids in their natal disks. While canonical models assume a
solar solid-to-gas mass ratio (epsilon=0.01) and neglect the back-reaction of solid component of the disk, recent work suggests that enhanced
metallicity can radically alter these torques. We quantify how elevated
metallicities (epsilon=0.03 and epsilon=0.1) modify the gas and solid torques, test widely used linear scaling prescriptions, and identify the regimes where solid back-reaction becomes decisive. We performed global, 2D hydrodynamic simulations that treat solid material as a pressureless fluid fully coupled to the gas through drag and include the reciprocal back-reaction force. The
planet was maintained on a fixed circular orbit, thus we computed static torques. The Stokes number was varied from 0.01 to 10, three surface-density slopes (p=0.5, 1.0, and 1.5) and three
accretion efficiencies (eta=0, 10, and 100%) were explored. Torques, obtained by rescaling canonical epsilon=0.01 results, were compared with direct simulations. Solid torques scale linearly with epsilon, but gas torques deviate by 50-100% and can even reverse sign for St<=1 in epsilon=0.1 disks. These are due to strong, feedback-driven, asymmetric gas perturbations in the co-orbital region, amplified by rapid planetary
accretion. Solid back-reaction in high-
metallicity environments can dominate the migration torque budget of low-mass
planets. Simple
metallicity rescalings are therefore unreliable for St<=2, implying that precise migration tracks - particularly in metal-rich disks – require simulations that fully couple solid and gas dynamics. These results highlight
metallicity as a key parameter in shaping the early orbital architecture of planetary systems.
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Accelerator Physics
First observation of the $\gamma$-ray beam production by the backward Compton scattering of reflected synchrotron radiation in the extreme ultraviolet range
Norihito Muramatsu, Manabu Miyabe, Masahiro Okabe et al. (+8 more)
Compton scattering of
photons off high-energy electrons is a fundamental
quantum mechanical process widely utilized to produce a $\gamma$-ray beam for scientific research. Instead of injecting
laser light into a storage ring as a conventional way, we have developed an innovative method to achieve drastically higher energies approaching the ring energy by the backward Compton scattering of extreme ultraviolet (EUV) light. In this method, $92$ $\mathrm{eV}$
photons obtained from an undulator in a storage ring were reflected back to the original ring using a Mo/Si multilayer mirror. Consequently, $\gamma$-ray beam production through the EUV light Compton scattering using reflected synchrotron radiation was observed for the first time in a demonstration experiment conducted at the $1$ $\mathrm{GeV}$ ring, NewSUBARU. The measured energy spectrum was well reproduced by a theoretical calculation with the maximum energy of $0.543$ $\mathrm{GeV}$. The production rate was $1.4 \pm 0.1$ kcps for the energies above $0.160$ $\mathrm{GeV}$. This rate was quantitatively explained by the luminosity and the scattering cross section. The present work paved the way to create a new $\gamma$-ray beam source for future applications such as
hadron photoproduction experiments.
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All authors Norihito Muramatsu, Manabu Miyabe, Masahiro Okabe, Schin Date, Tetsuo Harada, Kazuhiro Kanda, Shuji Miyamoto, Haruo Ohkuma, Hajime Shimizu, Shinsuke Suzuki, Atsushi Tokiyasu
Optics
Automatic Classification of Laser Peening Quality Using Acoustic Signals
Bohumil Kolář, Jan Kočí, Michal Kotek et al. (+2 more)
Laser Shock Peening increases the fatigue life of metallic components by introducing beneficial compressive residual stresses. To achieve the desired effect, each individual
laser pulse must be delivered correctly.
Laser Shock Peening quality is typically verified by destructive and time-consuming residual stress measurements or by subjective operator judgement, which is non-objective and unsuitable for continuous in-line control. We propose a simple, low-cost and robust method based on the analysis of the acoustic response that automatically classifies individual
laser pulses as defect-free or defective. We show that the acoustic response captured by a low-cost microphone carries sufficiently informative signatures to reliably distinguish correct from incorrect impacts and enables quality control at the level of single pulses. The method provides a non-destructive and objective route to real-time monitoring of
Laser Shock Peening, with the potential to increase process reliability and support industrial deployment of this technology without the need for subsequent destructive measurements.
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All authors Bohumil Kolář, Jan Kočí, Michal Kotek, Tomáš Martinec, Ivan Mašín
Instrumentation and Detectors
Development of Low-Noise Two-stage dc-SQUID for TES Detector Readout
Nan Li, Mengjie Song, Sixiao Hu et al. (+9 more)
Direct-current superconducting
quantum interference devices (dc-SQUIDs) are one of the most sensitive
magnetic detectors. These sensors are extensively used in the readout of superconducting transition edge sensors (TESs), which are used for the detection of weak signals. A
cosmic microwave background (CMB) polarization
telescope operating in 22-48 GHz is currently under developing. The TESs calorimeter of the
telescope will be readout by a time-division multiplexer (TDM) SQUID readout system. We develop a two-stage dc-SQUID amplifier
circuit, comprising an input-stage SQUID with 4 SQUID
cells and a series SQUID array (SSA) with 100 SQUID
cells. This configuration has been shown to achieve extremely high signal gain while effectively controlling system noise. We assess the system noise at $300$ $mK$ in an adiabatic demagnetisation refrigerator (ADR). The the measured
magnetic flux noise of the two-stage SQUID
circuit system is approximately $0.3$ ${\mu}\Phi_{0}/\sqrt{Hz}$ at $10$ $kHz$. The current noise equivalent to the input coil of input SQUID is about $2.4$ $pA/\sqrt{Hz}$. This result meets the low-noise readout requirements of the CMB TES and other applications with TES detectors.
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All authors Nan Li, Mengjie Song, Sixiao Hu, Wentao Wu, Songqing Liu, Tangchong Kuang, Yudong Gu, Xiangxiang Ren, Xufang Li, He Gao, Zhengwei Li, Congzhan Liu
Plasma Physics
Advanced Shaping of Quasi-Bessel Beams for High-Intensity Applications
Jérôme Touguet, Igor Andriyash, Ronan Lahaye et al. (+4 more)
Quasi-Bessel beams produced by axiparabolas are increasingly used in high-intensity
laser applications, yet their longitudinal profiles exhibit unwanted oscillations that limit their effectiveness. Here we identify the physical origin of these distortions and develop a general strategy to control the on-axis intensity of extended focal lines. By combining analytical insight with numerical and experimental validation, we show how both smooth and sharply structured longitudinal profiles can be reliably produced. This establishes a robust framework for tailoring quasi-Bessel beams in regimes relevant to
laser-
plasma acceleration, advanced
photon sources, and other high-field applications.
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All authors Jérôme Touguet, Igor Andriyash, Ronan Lahaye, Guillaume Chapelant, Julien Gautier, Lucas Rovige, Cédric Thaury
Computational Physics · Cross-listed from math.NA
Unified Regularization of 2D Singular Integrals for Axisymmetric Galerkin BEM in Eddy-Current Evaluation
Yao Luo
This paper presents an axisymmetric Galerkin boundary element method (BEM) for modeling eddy-current interactions between excitation coils and conductive objects. The formulation derives boundary integral equations from the Stratton-Chu representation for the azimuthal component of the vector potential in both air and conductive regions. The central contribution is a unified regularization framework for the two-dimensional (2D) singular integrals arising in Galerkin BEM. This framework handles both logarithmic and Cauchy singularities through a common set of integral transformations, eliminating the need for case-by-case analytical singularity extraction and enabling straightforward numerical quadrature. The regularization and quadrature stability are proved and verified numerically. The method is validated on several representative axisymmetric geometries, including cylindrical, conical, and spherical shells. Numerical experiments demonstrate consistently high accuracy and computational efficiency over the tested frequency interval and coil lift-off distances. The results confirm that the proposed axisymmetric Galerkin BEM, combined with the integral transformation technique, provides a robust and efficient framework for axisymmetric eddy-current nondestructive evaluation.
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Atomic Physics
R-Matrix Theory for Electron-Ion Collisions in Plasmas
Chao Wu, Wen Hao Xia, Yong Wu et al. (+4 more)
Electron-atom collisions in warm dense
plasmas are crucial for astrophysics and controlled fusion research, where calculating short-range scattering
matrices under screening
plasma potentials is essential. While electron-neutral atom collisions are tractable using the standard Riccati-Bessel wavefunctions in the asymptotic region, electron-ion collisions face challenges due to the extended range of the screened Coulomb potential, which lacks analytical solutions or numerical code packages for asymptotic regular and irregular wavefunctions. We introduce an R-
matrix theoretical framework for general screened potentials and develop a numerical method to compute these asymptotic wavefunctions efficiently. Our approach yields short-range scattering phase shifts that remain invariant with respect to the matching point in the asymptotic region. Applying the Debye screening potential as an illustrative example, we calculate elastic and electron-impact excitation collision strengths for H-like ions (He, C, Ne) across varying temperatures and densities. The calculations show that Debye screening systematically modifies resonance structures and progressively lowers excitation thresholds. Nevertheless, the effective collision strengths and rate coefficients exhibit approximate scaling laws. These findings enable convenient access to electron collision data in
plasma environments, advancing
plasma diagnostics and modeling.
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All authors Chao Wu, Wen Hao Xia, Yong Wu, Jun Yan, Ming Li, Jian Guo Wang, Xiang Gao
Optics · Cross-listed from cond-mat.mtrl-sci
Near-field effects on cathodoluminescence outcoupling in perovskite thin films
Robin Schot, Imme Schuringa, Álvaro Rodríguez Echarri et al. (+7 more)
Halide perovskite
semiconductors are a promising material for high-efficiency
solar cells. Their optical properties can vary within and between crystallographic grains. We present spatially-resolved cathodoluminescence (CL) spectroscopy at 2 keV and 5 keV on polycrystalline CsPbBr3 perovskite films to study these variations at the nanoscale. The CL maps show a strongly reduced intensity near the polycrystalline grain boundaries. We perform numerical simulations of the far-field emission of the electron beam-generated optical near fields using the surface profiles from AFM as input. We find that near grain boundaries the light outcoupling is strongly reduced due to enhanced internal reflection and light trapping at the curved surfaces. Lateral variations in CL intensity inside grains are due to Fabry-Perot-like resonances in the film, with the substrate acting as a back reflector. Our results show that near-field coupling and interference effects can dominate nanoscale luminescence maps of halide perovskite films. The results are broadly relevant for the analysis of cathodoluminescence and photoluminescence of corrugated thin films.
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All authors Robin Schot, Imme Schuringa, Álvaro Rodríguez Echarri, Lars Sonneveld, Tom Veeken, Yang Lu, Samuel D. Stranks, Albert Polman, Bruno Ehrler, Saskia Fiedler
Optics
High-sensitivity silicon nitride microring resonator opto-fluidic sensor
Davey O. Armstrong, Sherif Ibrahim, Shirin Naserikarimvand et al. (+4 more)
Photonic integrated
circuit devices can be used as refractometric opto-fluidic sensors to detect the presence of analytes in solution at low concentrations. In this work, we investigate the refractive index sensitivity of silicon nitride microring resonator based photonic integrated
circuit fluidic sensors. The performance of a foundry fabricated sensor is measured over the C-band in the presence of
liquid samples achieving a mean sensitivity of 579 nanometres per refractive index unit. This demonstration of a scalable, high-sensitivity opto-fluidic sensor, compatible with recognition marker surface functionalisation, opens the way to applications in environmental and bio-sensing.
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All authors Davey O. Armstrong, Sherif Ibrahim, Shirin Naserikarimvand, Simon Whelan, Owen J. Guy, Anthony J. Bennett, John P. Hadden
Computational Physics
Rimu.jl: Random integrators for many-body quantum systems
Matija Čufar, C. J. Bradly, Ray Yang et al. (+2 more)
Rimu$.$jl is a Julia package for solving many-body
quantum problems. The core of the package is a
matrix-free implementation of
Hamiltonians and other operators and compact representation of Fock states, which together allow for efficient methods suitable for high-performance computing. Rimu$.$jl includes a Julia implementation of the full configuration interaction
quantum Monte Carlo (FCIQMC)
algorithm which is a type of projector QMC
algorithm for stochastically solving the time-independent Schrödinger equation. It also includes many well-known model
Hamiltonians, and an interface for exact diagonalisation based on external
eigenvalue solvers. Both the
stochastic and exact diagonalisation methods are accessed with a CommonSolve$.$jl interface. We describe the FCIQMC
algorithm and how to obtain
estimators of observables as well as the key features of the implementation.
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All authors Matija Čufar, C. J. Bradly, Ray Yang, Elke Pahl, Joachim Brand