Optics
Deep Learning-Enabled Invisible Electromagnetic Scattering Amplifier
Qike Xie, Qin Liao, Xiaofan Ji et al. (+2 more)
With the rapid development of micro-electro-mechanical systems, electrically small micro-targets, such as subwavelength micro unmanned aerial vehicles and bionic mosquito
robots, exhibit ultra-low scattering cross section, which brings severe challenges to their effective detection. To address this problem, an Invisible Electromagnetic Scattering Amplifier (IESA) is designed by combining finite-element electromagnetic simulation with a forward lossless tandem neural network. The IESA realizes the dual-functional integration of intrinsic electromagnetic invisibility (near-zero scattering) for itself and significant scattering amplification for subwavelength targets entering its air sensing region. Electromagnetic simulations verify that the designed IESA can achieve a stable scattering amplification effect on subwavelength targets with a characteristic size of approximately 0.1{\lambda}0, regardless of their spatial positions or
geometric shapes, with a maximum scattering cross section amplification factor of 8.58. The IESA breaks the technical bottleneck of the separate design of electromagnetic invisibility and scattering amplification functions. It shows potential for applications in the fields of radar detection, anti-terrorism security, micro-target monitoring, and adaptive electromagnetic sensing.
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All authors Qike Xie, Qin Liao, Xiaofan Ji, Yichao Liu, Fei Sun
Computational Physics · Cross-listed from cond-mat.stat-mech
Computing Nonequilibrium Transport from Short-Time Transients: From Lorentz Gas to Heat Conduction in One Dimensional Chains
Davide Carbone, Vincenzo Di Florio, Stefano Lepri et al. (+1 more)
We test the Transient Time Correlation Function (TTCF) method to compute nonequilibrium transport coefficients, highlighting its conceptual and practical difference from the standard time-average approach. While time averages extract transport properties from long stationary trajectories and discard transient dynamics, TTCF adopts the complementary strategy: it exploits the information contained in short-time transients following the onset of an external perturbation, while discarding the long-time
evolution once stationarity is reached. We revisit the theoretical framework of TTCF and assess its numerical performance through representative case studies, the Lorentz gas and a many-body system, namely a chain of oscillators with anharmonic pinning potential. By direct comparison with time averages, we show that for the Lorentz gas TTCF yields consistent transport coefficients in both linear and nonlinear regimes at a reduced computational cost. Moreover, the TTCF displays superior precision in the linear-response regime, and remains reliable in non-ergodic situations, revealing the presence of regions of phase space corresponding to different behaviors, as well as the possibility of phase transitions. For the anharmonic chain, we show that TTCF is a scalable and efficient alternative for the numerical study of nonequilibrium transport.
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All authors Davide Carbone, Vincenzo Di Florio, Stefano Lepri, Lamberto Rondoni
Atomic Physics · Cross-listed from quant-ph
Analysis of the action of conventional trapped-ion entangling gates in qudit space
Pavel Kamenskikh, Nikita Semenin, Ilia Zalivako et al. (+4 more)
Qudits, or multi-level
quantum information carriers, present a promising path for scaling
quantum computers. However, their use introduces increased complexity in
quantum logic, necessitating careful control of relative phases between different qudit levels. In trapped-ion systems, entangling operations accumulate phases on specific levels that are no longer global, unlike in
qubit architectures. Furthermore, the structure of multi-level gates becomes increasingly intricate with higher-dimensional
Hilbert spaces. This work explores the theory of these additional local and nonlocal phases, accumulated in Mølmer–Sørensen and Light-shift gates. We propose methods to actively compensate for these phases, enhance gate robustness against parameter fluctuations, and simplify native gates for more efficient
circuit decomposition. Our results pave the way toward the practical and scalable implementation of qudit-based
quantum processors.
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All authors Pavel Kamenskikh, Nikita Semenin, Ilia Zalivako, Vasiliy Smirnov, Ilya Semerikov, Ksenia Khabarova, Nikolay Kolachevsky
Physics and Society
A Bayesian approach to out-of-sample network reconstruction
Mattia Marzi and Tiziano Squartini
Networks underpin systems that range from finance to biology, yet their structure is often only partially observed. Current reconstruction methods typically fit the parameters of a model anew to each snapshot, thus offering no guidance to predict future configurations. Here, we develop a
Bayesian approach that uses the information about past network snapshots to inform a prior and predict the subsequent ones, while quantifying uncertainty. Instantiated with a single-parameter fitness model, our method infers link probabilities from node strengths and carries information forward in time. When applied to the Electronic
Market for Interbank Deposit across the years 1999-2012, our method accurately recovers the number of connections per bank at subsequent times, outperforming probabilistic
benchmarks designed for analogous, link prediction tasks. Notably, each predicted snapshot serves as a reliable prior for the next one, thus enabling self-sustained, out-of-sample reconstruction of evolving networks with a minimal amount of additional data.
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Fluid Dynamics
Prandtl number dependence of rotating internally heated convection
Rodolfo Ostilla-Mónico and Ali Arslan
We investigate the influence of the Prandtl number ($Pr$) on penetrative internally heated convection (IHC) in both non-rotating and rotating regimes using three-dimensional direct numerical simulations. By varying $Pr$ between 0.1 and 100, we show that the global mean temperature $\langle \overline{T} \rangle$ is not very sensitive to $Pr$, and is primarily controlled by the dynamics of the unstably stratified top boundary layer. In contrast, the Prandtl number dictates the behavior of the lower, stably stratified region and affects the vertical convective heat flux $\langle \overline{wT} \rangle$. In the non-rotating case, low $Pr$ fluids exhibit a “
symmetry recovery” where turbulent stirring agitates the stable layer, whereas high $Pr$ fluids transition toward a “dead zone” of suppressed fluctuations. Under rotation, we find that $\langle \overline{wT} \rangle$ is enhanced across all Prandtl numbers, though global cooling efficiency, measured by the reduction in $\langle \overline{T} \rangle$, is only improved for $Pr\ge1$ due to the emergence of Ekman pumping. These results demonstrate that while IHC shares some scaling similarities with Rayleigh-Bénard convection at the top boundary, the internal stratification creates a unique sensitivity to $Pr$ that is critical for understanding heat transport in planetary and
stellar interiors.
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Applied Physics · Cross-listed from quant-ph
Deep squeezing or cooling the fluctuations of a parametric resonator using feedback
Adriano A. Batista, Raoni S. N. Moreira and A. A. Lisboa de Souza
Here we analyze ways to achieve deep subthreshold parametric squeezing or cooling of a single degree-of-freedom parametric resonator enhanced by a lock-in amplifier feedback loop. Due to the feedback, the dynamics of the parametric resonator becomes more complex and a
Hopf bifurcation at the instability threshold can occur. Initially, we calculate the phase-dependent gain of parametric amplification with feedback of an added ac signal. In one approach, we obtain the amplification gain approximately using two independent approaches: the averaging method and the harmonic balance method. We also obtain this gain more exactly using Floquet theory and Green's functions methods. The
Hopf bifurcation was predicted by the harmonic balance method and by Floquet theory, but not by the averaging method. In our analysis of fluctuations, we
Fourier analyze the response of the parametric resonator with feedback to an added white noise. We were able to calculate, in addition to the noise spectral density, the squeezing of fluctuations in this resonator with feedback. Very strong squeezing or cooling can occur. Deamplification and cooling occur near the
Hopf bifurcation, whereas squeezing occurs near a saddle-node bifurcation.
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Physics and Society · Cross-listed from econ.GN
Selecting representative community partitions under modularity degeneracy: the STAR method
Francesca Grassetti and Rossana Mastrandrea
Community detection based on modularity maximization is one of the most widely used approaches for uncovering mesoscale structures in complex networks. However, it is well known that the modularity function exhibits a highly degenerate optimization landscape: a large number of structurally distinct partitions attain close modularity values. This degeneracy raises issues of instability, reproducibility, and interpretability of the detected communities. We propose a simple and user-friendly post-processing method to address this problem by selecting a representative partition among the set of high-modularity solutions. The proposed approach is model-agnostic and can be applied a posteriori to the output of any modularity-based community detection
algorithm. Rather than seeking the optimal partition in terms of modularity, our method aims to identify a solution that best represents the structural features shared across degenerate partitions. We compare our approach with consensus clustering methods, which pursue a similar objective, and show that the resulting partitions are highly consistent, while being obtained through a substantially simpler procedure that does not require additional optimization steps or external software packages. Moreover, unlike standard consensus clustering techniques, the proposed method can be applied to networks with both positive and negative edge weights, making it suitable for a wide range of applications involving signed networks and correlation-based systems, such as social, financial, and neuroscience networks. Overall, the method provides a practical and robust tool for handling degeneracy in modularity-based community detection, combining simplicity with broad applicability across different types of networks and real-world problems.
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Chemical Physics
Inclusion of Three-body Correction to Relativistic Equation-of-Motion Coupled Cluster Method: The Application to Electron Detachment Problem
Mrinal Thapa and Achinyta Kumar Dutta
We present the formulation and implementation of triples correction scheme to the relativistic equation-of-motion coupled-cluster method for ionization potential. Both full and partial triples correction schemes are implemented using the exact two-component atomic mean-field (X2CAMF)
Hamiltonian in combination with Cholesky-Decomposition (CD) of two-electron integrals and a frozen natural spinor (FNS) truncation scheme to reduce computational cost.
Benchmark calculations on halide anions, noble gas atoms, hydrogen halides, and dihalogen molecules demonstrate that triple excitations are essential for achieving quantitative ionization potentials, reducing mean absolute errors to approximately 0.01–0.08~eV relative to reference and experimental values. The X2CAMF approximation reproduces four-component Dirac-Coulomb results with negligible deviations, while the CD-FNS strategy yields substantial reductions in wall time. The resulting partial triples correction scheme scales as non-iterative $\mathcal{O}(n^7)$ with storage comparable to CCSD, offering an accurate and practical route for relativistic ionization energy calculations in heavy-element systems.
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Optics
Flat Bands from Diffraction in Periodic Systems
Joel Lehikoinen, Rebecca Heilmann, Aron J. J. Dahlberg et al. (+5 more)
Periodic photonic structures enable precise control over the light-matter interaction through band structure engineering. Certain
lattice geometries exhibit dispersionless flat bands, characterized by vanishing group velocity and diverging density of states, which present unique opportunities for applications such as slow light, nonlinear optical processes and controlling photoluminescence. However, thus far, flat bands have not been reported in systems where the
lattice sites are radiatively coupled over a long range. Here we show that
lattices consisting of superposed equispaced one dimensional chains exhibit flat bands with a purely diffractive origin, with the energies and angles of the flat bands controlled by the geometrical parameters of the
lattice and the unit
cell. The flat bands extend over all angles, can have linewidths on the order of a few nanometers, and are linearly polarized. We experimentally observe flat bands at predicted energies in
lattices of gold nanoparticles at near-infrared frequencies using
Fourier spectroscopy. Our results provide a general and efficient design strategy for
lattices with flat, polarized dispersions for applications such as flat-band lasing, enhancing light-matter interaction, and controlling the emission or absorption of electromagnetic radiation over a wide spectral range.
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All authors Joel Lehikoinen, Rebecca Heilmann, Aron J. J. Dahlberg, Eero Härmä, Malek Mahmoudi, Arpan Dutta, Konstantinos S. Daskalakis, Päivi Törmä
Optics
Chains of nanoparticles for flat-band emission and lasing
Rebecca Heilmann, Joel Lehikoinen, Sioneh Eyvazi et al. (+2 more)
Controlling light-matter interactions is central to photonic technologies ranging from
lasers to optical information processing. Suitably designed photonic structures give rise to flat (dispersionless) bands, where the density of states diverges, and group velocity goes to zero, allowing light localization. These properties make flat bands attractive for lasing; however, designing photonic structures supporting flat bands suitable for lasing is challenging. Here, we introduce nanoparticle chain
lattices. These chain geometries provide long-range coupled systems that support, at predictable wavelengths, bands that are totally flat and extend over the full angular range. We demonstrate lasing in the transverse-
magnetic (TM) mode of single chains of nanoparticles and explain the transition from flat band lasing to the single-mode normal-incidence (Gamma-point) lasing as the number of chains is increased. Moreover, we show partially coherent emission from square and triangular two-dimensional chain
lattices. The excited modes depend on the pump power and polarization. Our results establish chain
lattices as a versatile platform for exploring flat band lasing and suggest new routes toward narrowband, linearly polarized, and bright light sources with tailored coherence.
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All authors Rebecca Heilmann, Joel Lehikoinen, Sioneh Eyvazi, Evgeny A. Mamonov, Päivi Törmä
Optics
From raw data to processed spectra: A step-by-step guide
Erik F. Woering and Richard Hildner
Optical spectroscopy is an important and widely used technique, for instance, to characterize new materials and to identify unknown compounds. Spectra are typically reported as a function of the wavelength of light, yet the information extracted from such spectra can be misleading. In contrast, spectra represented as a function of the frequency (or
photon energy) allow for a more direct extraction of the intrinsic
quantum-mechanical properties of the materials under investigation. Here we discuss this conversion for absorption, fluorescence and fluorescence excitation spectra. We show step-by-step the different factors that lead to a rescaling of the measured absorption and fluorescence signals. This paper will assist instructors who aim at developing an (under-)graduate lab to introduce into the methodology and terminology of spectroscopic experiments and to provide clear, step-by-step guidelines for data analysis and representation.
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Computational Physics · Cross-listed from quant-ph
Wesley Lewis, Darsh Pareek, Umesh Kumar et al. (+1 more)
Matrix representations of
quantum operators are computationally complete but often obscure the structural
topology of information flow within a
quantum circuit \cite{nielsen2000}. In this paper, we introduce a generalized graph-theoretic framework for analyzing
quantum operators by mapping
unitary matrices to directed graphs; we term these structures Imperfect Graphs or more formally as Topological Structure of Superpositions(TSS) as a tool to devise better
Quantum Algorithms. In this framework, we represent computational basis states as vertices. A directed edge exists between two vertices if and only if there is a non-zero amplitude transition between them, effectively mapping the support of the
unitary operator. In this paper we deliberately discard probability amplitudes and phase information to isolate the connectivity and reachability properties of the operator. We demonstrate how TSS intuitively helps describe gates such as the Hadamard, Pauli-(X,Y,Z) gates, etc \cite{nielsen2000}. This framework provides a novel perspective for viewing
quantum circuits as discrete dynamical systems \cite{childs2009,aharonov2001} Keywords:
Quantum Algorithms,
Unitary Matrix Approach, Topological Structure of Superpositions (TSS), Graph Theory
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All authors Wesley Lewis, Darsh Pareek, Umesh Kumar, Ravi Janjam
Fluid Dynamics
Frequency-Dependent Magnetic modulation of deposition morphology
S.K. Saroj and P.K. Panigrahi
This paper presents a novel approach for
magnetic modulation of deposition morphology in an evaporating ferrofluid droplet. The
magnetic field strength and ferrofluid concentration are kept unchanged, while the actuation frequencies are varied from 0.016 Hz to 5 Hz. In the absence of a
magnetic field, a coffee-ring formation is observed and consistent with previous studies\cite{deegan1997capillary,deegan2000contact,saroj2019drying}. The application of a time-dependent
magnetic field significantly modifies the deposition morphology. The periodic
magnetic field induces the formation of multiple concentric rings during evaporation. The number of rings initially increases with increasing actuation frequency of the electromagnet. However, beyond a critical actuation frequency ($f_c = 0.2\,\text{Hz}$), the number of rings decreases. At higher actuation frequencies,
magnetic particles preferentially deposit in the central region of the droplet, resulting in suppression of the coffee-ring effect. Additionally, the thickness of the inner rings and the ring spacing decrease with increasing actuation frequency up to critical actuation frequency. The transition from multi-ring formation to coffee-ring suppression is governed by the competition among
magnetic forcing, capillary flow, and particle
diffusion. The underlying physical mechanisms responsible for droplet dynamics and deposition morphology under periodic
magnetic fields are evaluated using scaling arguments. The results demonstrate that diffusive particle transport plays a dominant role in determining the deposition pattern. A non-dimensional
magnetic switching number, based on the
magnetic perturbation timescale, is introduced as a control parameter to characterize the frequency-dependent deposition behavior.
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Biological Physics · Cross-listed from q-bio.BM
Spectral analysis of protein backbone geometry reveals abrupt helix–coil boundaries
Yiquan Wang
The boundaries of cooperative helix–coil transitions influence
protein allostery and conformational dynamics, yet the persistent one-to-two-residue ambiguity in their assignment remains poorly characterized. We apply the discrete Hasimoto map to translate three-dimensional C$_\alpha$ backbone geometry into a one-dimensional discrete nonlinear Schrödinger effective potential and analyze its spatial-frequency structure. Helical segments appear as near-integrable, low-
entropy states whose spectral power concentrates at the zero-frequency mode, whereas coil regions show broadband fluctuations. A pointwise integrability residual and a windowed spectral
entropy separate the two phases with ROC AUC values of 0.783 and 0.715, and their combination reaches 0.803, while combining the residual instead with a low-frequency energy ratio reaches 0.815. Across 1\,986
proteins and 19\,148 of 21\,107 fitted helix–coil boundaries the transition is abrupt, with a median sigmoid width of 0.145 residues that measures the steepness of a single-step discrete jump rather than a literal sub-residue distance; the transition is directionally asymmetric, with helix exits sharper than entries. Across the full
dataset every C$_\alpha$ geometry-based assignment, including DSSP-calibrated P-SEA and both spectral probes, loses agreement with the DSSP hydrogen-bond reference most acutely at these boundaries, indicating that the assignment ambiguity is a general feature of C$_\alpha$ geometry rather than any single
algorithm. The windowed spectral probe is subject to a Gabor resolution limit and is therefore outperformed by the pointwise probe, which attains the
lattice-limited resolution.
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Physics Education
Tinkering in Primary School: From Episode to Science Practice
S. Rini and S. Ricciardi
This study discusses the opportunity to integrate tinkering, a constructionist practice, into formal education, highlighting its potential and challenges. We propose a model through which teachers can blend the open exploratory nature of tinkering with structured learning in primary school classrooms, focusing on Physics Education. Despite pandemic-induced limitations, feedback from 20 teachers and analysis of fishbowl protocols revealed the positive impact of tinkering on classroom dynamics, teacher engagement, and student access to knowledge. Our findings indicated that tinkering can surface relevant scientific questions. Nevertheless, teachers feel unprepared to tackle them in the classroom. This evidence will guide our future co-designs to enhance learning experiences and address the complexities of incorporating tinkering into formal education.
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Atmospheric and Oceanic Physics
A Generalized Richardson Number Diagnostic for Turbulence in the Free Atmosphere
Mohamed Foudad, Miguel A.C. Teixeira, Paul D. Williams et al. (+1 more)
A new Richardson number formulation, Ri_new, is introduced to improve the diagnosis of
turbulence in the stratified free atmosphere. The formulation is derived from the turbulent kinetic energy budget and accounts for both vertical wind shear and horizontal shear (deformation and divergence), weighted by the ratio of horizontal to vertical eddy viscosities (K_mh/K_mv). This extends the classical Richardson number Ri_old, which accounts only for vertical shear. The diagnostics Ri_new , Ri_old ,and the widely used
Turbulence Index 1 (TI1), computed from ERA5 reanalysis, are evaluated using more than 247 million automated
turbulence reports from commercial aircraft (2017–2024). Across various
turbulence intensity thresholds, Ri_new consistently outperforms the other diagnostics, resulting in higher AUC values and improved probability of detection at operationally relevant false-alarm rates. The highest skill is obtained for K_mh/K_mv approximately 5000. Seasonal and regional evaluations indicate that the added value of Ri_new is largest where
turbulence generation involves both vertical and horizontal shear, such as over the contiguous United States and during summer. Ri_new remains the best-performing diagnostic in all regions and seasons. Spatial case studies show that Ri_new identifies 83–98% of observed moderate-or-greater
turbulence events compared with 54–85% for Ri_old. This substantial improvement in detection comes with a much smaller increase in false alarms, confirming that Ri_new provides a more physically realistic representation of
turbulence-prone regions. These results demonstrate that incorporating horizontal wind shear into the Richardson number yields a physically consistent and statistically robust improvement in
turbulence diagnostics, with relevance for research and operational applications.
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All authors Mohamed Foudad, Miguel A.C. Teixeira, Paul D. Williams, Thorsten Kaluza
Biological Physics · Cross-listed from q-bio.NC
Limits of optimal decoding under synaptic coarse-tuning
Ori Hendler, Ronen Segev and Maoz Shamir
Sensory information propagates through successive processing stages in the
brain, where synaptic weight patterns between stations determine how downstream
neurons decode information from upstream populations. Although optimized synaptic connectivity can enhance information transmission, it requires precise weight tuning. Recent evidence depicting substantial synaptic
volatility raises two fundamental questions: How does coarse-tuning of synaptic connectivity affect information transmission? What strategies could the nervous system employ to maintain reliable communication despite synaptic fluctuations? We addressed these questions by analyzing the signal-to-noise ratio ($SNR$) for binary stimulus discrimination under two decoding schemes: a naive population average and an optimized linear decoder. For the naive decoder, we found that $SNR$ remains largely insensitive to synaptic imprecision, since performance is already limited by correlated noise in neuronal responses. For the optimal decoder, we identified three distinct regimes. Under weak coarse-tuning, $SNR^2$ scales linearly with population size $N$. Under moderate coarse-tuning, scaling becomes sublinear. Under strong coarse-tuning, the regime most consistent with observed neuronal heterogeneity, $SNR$ saturates and can not be improved by recruiting larger populations. This limitation persists even when incorporating feedforward or recurrent network architectures. These findings suggest that in the biologically relevant regime of strong coarse-tuning, naive and optimal decoders can achieve qualitatively similar performance. The analysis shows that effective readout under synaptic
volatility is constrained to an invariant low-dimensional
manifold aligned with the naive decoder, potentially pointing to a fundamental principle for robust neural computation in the face of ongoing synaptic remodeling.
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Computational Physics
Emergent Rate Laws for Collective Lying-Standing Transitions
Anna Werkovits, Simon B. Hollweger and Oliver T. Hofmann
Lying-standing transitions in the first molecular monolayer at organic-inorganic interfaces strongly influence interface dipoles, energy-level
alignment, and growth modes, yet their collective kinetics remain difficult to predict. Here, we establish a quantitative adsorbate-to-kinetics relationship using first-principles-based kinetic Monte Carlo simulations combined with a mean-field coarse-graining strategy. Focusing on tetracyanoethylene on Cu(111), we show that the collective transition rate cannot be inferred from any single elementary step but emerges from coupled microscopic processes, including reorientation, adsorption, and
diffusion. A local two-step reorientation mechanism captures the
diffusion-limited regime, while
diffusion of lying molecules accelerates the transition in
diffusion-enhanced regimes by suppressing back-reorientation via vacancy-molecule decoupling. This effect is described by a regime-dependent
geometric factor accounting for deviations between single-molecule and collective rate constants. By varying molecular size and footprint ratio, we demonstrate that geometry is an intrinsic control parameter. While the collective rate scales approximately with molecular area, increasing the footprint ratio between lying and standing configurations yields order-of-magnitude accelerations due to enhanced vacancy creation and
diffusion-assisted stabilization. Finally, we derive an analytical expression for the collective reorientation rate constant linking temperature- and pressure-dependent microscopic rate constants to
geometric parameters. The formulation reproduces the simulations across kinetic regimes and provides transferable design principles for engineering lying-standing transition timescales at organic-inorganic interfaces.
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Optics
Room-temperature, continuous wave lasing in planar microcavities with quantum dots
Andrey Babichev, Mikhail Bobrov, Alexey Vasilev et al. (+7 more)
High-quality planar cavities with low-absorption mirrors based on $Al_{0.2}Ga_{0.8}As/Al_{0.9}Ga_{0.1}As$ layers demonstrate continuous wave lasing at a wavelength of 956 nm. At 300 K, the threshold power density and quality-factor at the threshold are (4.2$\pm$0.3) $kW/cm^2$ and (6800$\pm$220). Increasing the pump level above two thresholds lead to an enlargement in the quality-factor to at least 19000. Efficient lateral heat dissipation in the planar
semiconductor microcavity is confirmed by a low mode-energy shift of approximately 400 $\mu$eV at two lasing thresholds.
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All authors Andrey Babichev, Mikhail Bobrov, Alexey Vasilev, Sergey Blokhin, Nikolay Maleev, Ivan Makhov, Natalia Kryzhanovskaya, Leonid Karachinsky, Innokenty Novikov, Anton Egorov
Medical Physics
Solderable Microcontroller-Integrated E-Textiles using UV-Tape-Assisted Laser Patterning Technique
Naoto Tomita, Suguru Sato, Toshihiro Takeshita et al. (+5 more)
In this study, we developed a UV-tape-assisted
laser patterning (UT-
Laser) technique that enables the simple transfer-based formation of wiring with line widths below 200 $\mu$m onto textile substrates. With the rapid advancement of wearable devices capable of acquiring various types of physiological and environmental information, research on electronic textiles (e-textiles)-in which electronic components are integrated into fabrics and clothing-has progressed considerably. However, integrating high-performance, rigid electronic components onto textiles remains challenging: the diameter of textile fibers limits the formation of fine wiring, making reliable mounting of such components difficult. To address these challenges, we devised the UT-
Laser technique, in which thin foil or film materials are
laser vector-cut on UV tape, and the adhesive strength is controlled through UV exposure. The unnecessary portions are selectively and collectively peeled away to form fine wiring, which is subsequently transferred onto the textile substrate. This approach enables facile fabrication of fine wiring with line widths below 200 $\mu$m on textiles. Furthermore, by forming fine wiring from a flexible copper clad laminate and transferring it onto heat-resistant glass cloth, electronic components can be soldered directly, allowing the fabrication of e-textile devices capable of withstanding more than 10,000 bending cycles. The prototype e-textile device fabricated using the proposed method integrates a microcontroller, USB connector, battery holder, flash
memory, inertial measurement unit, and environmental sensors, and successfully acquires data related to stair climbing, respiration, and changes in body temperature during sleep.
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All authors Naoto Tomita, Suguru Sato, Toshihiro Takeshita, Aki Furusawa, Jarred Fastier-Wooller, Shun Muramatsu, Toshihiro Itoh, Michitaka Yamamoto
Optics
Towards Polarization Routing of Magnetic and Electric Dipolar Emission with Dielectric Metasurfaces
Marijn Rikers, Ayesheh Bashiri, Katsuya Tanaka et al. (+4 more)
We investigate the polarization properties of emission associated with the
magnetic dipole and electric dipole transitions of europium(III) coupled to an anisotropic dielectric metasurface with polarization-engineered electric and
magnetic photonic local density of states. The metasurface consists of a square array of Mie-resonant elliptical a-Si:H dimers situated on an SiO$_2$ substrate and embedded in a PMMA film containing Eu(TTA)$_3$. Based on reciprocity principle, it was designed to achieve maximum electric (
magnetic) field enhancement in the dimer gap at 610 nm (590 nm) for $x$-polarized ($y$-polarized) normally incident light in order to selectively enhance the electric dipole (
magnetic dipole) emission into the $x$-polarized ($y$-polarized) emission channel, respectively. Momentum-resolved spectroscopy and back-focal plane imaging of emission of the fabricated light-emitting metasurface clearly reveal the intended polarization-dependent emission behaviour, with the $x$-polarized ($y$-polarized) emission showing a reduced (enhanced) ratio of the
magnetic-/electric dipole emission intensity, correspondingly where the
magnetic dipole emission is enhanced with a
magnetic field enhancement from the nanostructures. The demonstrated polarization-dependent interaction of a designed nanostructure with the electric- and
magnetic dipolar transitions of trivalent lanthanide ions opens an avenue towards routing of emission of different multipolar orders into different polarization channels.
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All authors Marijn Rikers, Ayesheh Bashiri, Katsuya Tanaka, Ángela Barreda, Duk-Yong Choi, Thomas Pertsch, Isabelle Staude
Physics and Society
On the equivalence between nonlinear graph-based dynamics and linear dynamics on higher-order networks
Lucas Lacasa
In network science, collective dynamics of complex systems are typically modelled as (nonlinear, often including many-body) vertex-level update rules evolving over a graph interaction structure. In recent years, frameworks that explicitly model such higher-order interactions in the interaction backbone (i.e. hypergraphs) have been advanced, somehow shifting the imputation of the effective nonlinearity from the dynamics to the interaction structure. In this work we discuss such structural–dynamical representation duality, and investigate how and when a nonlinear dynamics defined on the vertex set of a graph allows an equivalent representation in terms of a linear dynamics defined on the state space of a sufficiently richer, higher-order interaction structure. Using Carleman linearisation arguments, we show that finite
polynomial dynamics defined in the $|V|$ vertices of a graph admit an exact representation as linear dynamics on the state space of an hb-graph of order $|V|$, a combinatorial structure that extends hypergraphs by allowing vertex multiplicity, where the specific shape of the nonlinearity indicates whether the hb-graph is either finite or infinite (in terms of the number of hb-edges). For more general analytic nonlinearities, exact linear representation always require an hb-graph of infinite size, and its finite-size truncation provides an approximate representation of the original nonlinear graph-based dynamics.
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Optics
Trap-dependent current suppression of optically excited III-V nanowires at cryogenic temperatures
Myriam Rihani, Cristina Martinez-Oliver, Markus A. Scherrer et al. (+3 more)
The advancement of
quantum technology networks necessitates high-speed, low-thermal load, and minimal-noise communication links between cryogenic and room-temperature components. At the heart of modern telecommunication, lay optical interconnects allowing for large data transfer capabilities via optical fibers. However, cryogenic photonic technologies remain largely unexplored and require a detailed understanding of material behavior and defect dynamics at low temperatures. In this work, we present the first comprehensive study of integrated III-V
heterostructures operating at cryogenic temperatures down to 5K. Using an integrated n-InP/i-InGaAs/p-InP/p-InGaAs stack monolithically grown on silicon, we identify a temperature-dependent current-lowering mechanism arising from trap states becoming increasingly active below 140K. We demonstrate for the first time that these traps can be equivalently excited and controlled through either thermal or optical energy, revealing a dual modulation mechanism. These findings provide new insights into carrier transport and defect behavior in III-V
heterostructures at cryogenic temperatures, advancing the field of cryogenic photonics and offering a non-destructive approach for identifying and characterizing material
impurities in integrated
quantum and optoelectronic devices.
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All authors Myriam Rihani, Cristina Martinez-Oliver, Markus A. Scherrer, Heinz Schmid, Kirsten E. Moselund, Simone Iadanza
Biological Physics · Cross-listed from cond-mat.soft
Self-avoiding tethered surfaces are always flat
A. D. Chen, M. C. Gandikota, M. J. Kim et al. (+1 more)
The scaling behavior of fully flexible elastic tethered surfaces has been debated for decades. Some theories predict that self-avoiding surfaces would crumple in the absence of bending
rigidity, while most simulations suggested that they would remain flat. Recent simulations on ideal membranes with
lattice perforations suggest that systematically removing surface area from a membrane may provide an alternative way to crumpling self-avoiding surfaces. We perform extensive numerical simulations of two models of fully flexible elastic tethered surfaces in which self-avoidance can be systematically and continuously tuned to the ideal limit. We show that in the thermodynamic limit, these surfaces remain flat with a size exponent $\nu=1$ for any finite degree of self-avoidance, with or without membrane perforations.
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All authors A. D. Chen, M. C. Gandikota, M. J. Kim, A. Cacciuto
Plasma Physics
Out-of-time-ordered correlators for turbulent fields: a quantum-classical correspondence
Motoki Nakata
An extended formulation of out-of-time-ordered correlators (OTOCs), which quantify noncommutative operator growth and information scrambling in
quantum many-body systems, is developed for
turbulence dynamics as a representative of non-canonical
Hamiltonian systems. Based on the Wigner-Weyl transform and the Moyal bracket formalism, the semiclassical limit of OTOC for turbulent
plasmas governed by the Hasegawa-Mima equation is derived as an ensemble-averaged squared Lie-Poisson bracket between two chosen functionals of the turbulent fields. The classical-limit OTOC provides a quantitative measure of how a variational perturbation applied to one functional propagates across scales in the turbulent dynamics and how it affects another functional at a later time, thereby capturing scale-dependent or field-dependent transfer processes. In a quasilinear approximation with a strong zonal flow, we provide a closed analytic expression of the classical-limit OTOC to characterize the interaction between zonal and non-zonal modes. An asymptotic analysis shows that the OTOC grows quadratically at early time, while in the long-time strong-shear regime it approaches a finite saturated value with an inverse-square algebraic dependence. This behavior is attributed to zonal-flow shearing, which rapidly scrambles the non-zonal perturbation toward higher wavenumbers, thereby reducing the low-wavenumber non-zonal content that can feed back onto large-scale zonal modes.
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Data Analysis and Statistics · Cross-listed from cs.LG
Learning Complex Physical Regimes via Coverage-oriented Uncertainty Quantification: An application to the Critical Heat Flux
Michele Cazzola, Alberto Ghione, Lucia Sargentini et al. (+2 more)
A central challenge in scientific machine learning (ML) is the correct representation of physical systems governed by multi-regime behaviours. In these scenarios, standard data analysis techniques often fail to capture the nature of the data, as the system's response varies significantly across the state space due to its stochasticity and the different physical regimes. Uncertainty quantification (UQ) should thus not be viewed merely as a safety assessment, but as a support to the learning task itself, guiding the model to internalise the behaviour of the data. We address this by focusing on the Critical Heat Flux (CHF)
benchmark and
dataset presented by the OECD/NEA Expert Group on Reactor Systems Multi-Physics. This case study represents a test for scientific ML due to the non-linear dependence of CHF on the inputs and the existence of distinct microscopic physical regimes. These regimes exhibit diverse statistical profiles, a complexity that requires UQ techniques to internalise the data behaviour and ensure reliable predictions. In this work, we conduct a comparative analysis of UQ methodologies to determine their impact on physical representation. We contrast post-hoc methods, specifically conformal prediction, against end-to-end coverage-oriented pipelines, including (
Bayesian) heteroscedastic regression and quality-driven losses. These approaches treat uncertainty not as a final metric, but as an active component of the optimisation process, modelling the prediction and its behaviour simultaneously. We show that while post-hoc methods ensure statistical calibration, coverage-oriented learning effectively reshapes the model's representation to match the complex physical regimes. The result is a model that delivers not only high predictive accuracy but also a physically consistent uncertainty estimation that adapts dynamically to the intrinsic variability of the CHF.
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All authors Michele Cazzola, Alberto Ghione, Lucia Sargentini, Julien Nespoulous, Riccardo Finotello
Instrumentation and Detectors
Towards Low-Energy Electron High-Resolution Spectroscopy with Transition-Edge Sensors
R. Ammendola, A. Apponi, G. Benato et al. (+62 more)
We present a study of the energy resolution of transition-edge sensors (TESs) for the detection of electrons in the 100~eV kinetic energy range. The TES is a Ti-Au
bilayer with an active area of ($60 \times 60$) $\mu$m$^2$ and a critical temperature of $\sim 80$~mK. The electron source is based on vertically-aligned multiwall carbon nanotubes located inside the cryostat, with electrons generated via field emission. For electrons in the $(92 - 99)$~eV kinetic energy range, we obtain a Gaussian energy resolution for fully-absorbed electrons of ($0.48 \pm 0.04 \pm 0.06$)~eV, where the first uncertainty is statistical and the second systematic}. When considering the full-width at half-maximum of the peak \textcolor{black}{of the signal amplitude distribution}, the corresponding resolution is of ($1.4 \pm 0.2 \pm 0.3$)~eV. The former represents an improvement of $(47-60)\%$ with respect to previous results, and is mainly attributed to the reduction in the TES active area. The latter is instead an improvement of over a factor of 21, and is mainly due to the reduction in the emitting area of the electron source, which significantly suppresses electron back-scattering in proximity of the TES. These results represent a major milestone towards high-precision spectroscopy on low-energy electrons, which is a key objective for the PTOLEMY experiment.
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All authors R. Ammendola, A. Apponi, G. Benato, M. G. Betti, R. Biondi, P. Bos, M. Cadeddu, A. Casale, O. Castellano, G. Cavoto, L. Cecchini, E. Celasco, M. Chirico, W. Chung, A. G. Cocco, A. P. Colijn, B. Corcione, N. D'Ambrosio, M. D'Incecco, G. De Bellis, M. De Deo, N. de Groot, A. Esposito, M. Farino, S. Farinon, A. D. Ferella, L. Ferro, L. Ficcadenti, G. Galbato Muscio, S. Gariazzo, H. Garrone, F. Gatti, F. Malnati, G. Mangano, L. E. Marcucci, C. Mariani, J. Mead, G. Menichetti, M. Messina, E. Monticone, M. Naafs, S. Nagorny, V. Narcisi, F. Pandolfi, R. Pavarani, C. Pepe, C. Perez de los Heros, O. Pisanti, F. M. Pofi, A. D. Polosa, I. Rago, M. Rajteri, S. Ritarossi, N. Rossi, A. Ruocco, G. Salina, A. Santucci, M. Sestu, A. Tan, V. Tozzini, C. G. Tully, I. van Rens, F. Virzi, G. Visser, M. Viviani
Optics
Pure-amplitude holograms for high-efficiency generation of phase radial grating based radial carpet beams: Theory and experiments under plane-wave and Gaussian illumination
Saifollah Rasouli, Somaye Fathollazade and Mohammad Mohammadi
This study introduces a pure-amplitude hologram (PAH) for generating radial carpet beams (RCBs), which are conventionally produced using pure phase radial gratings (PRGs). The hologram is designed by
embedding the transmission function of a binary PRG into the phase argument of the cosine term(s) of an amplitude linear grating. When illuminated with a plane wave, this hologram generates RCBs in the non-zero diffraction orders, and when illuminated with a Gaussian beam, it generates RCB-like patterns at specific propagation distances. This method entirely eliminates the need for complex and expensive spatial light modulators (SLMs). The study presents a theory of diffraction for plane and Gaussian beams from such holograms, including a specific theoretical treatment of Gaussian beam diffraction from PRGs. Through theoretical analysis and experiments, we demonstrate how different RCBs can be generated at different diffraction orders due to the phase-amplitude enhancement resulting from multiplying the diffraction order number by the phase amplitude of the embedded base PRG, when the illuminating beam is a plane wave. For the Gaussian beam case, we show how different RCB-like patterns can be generated at different diffraction orders for the same reason, though only at specific propagation distances. Experimental and numerical results indicate that this technique yields RCBs and RCB-like patterns with approximately five times the useful power of their SLM-generated counterparts, demonstrating significantly higher power efficiency. This advantage renders the proposed method highly suitable for applications such as multiple optical trapping and free-space optical communication.
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Classical Physics
Mechanics and thermodynamics: A link between the two theories
Henri Gouin
In this note, we analyze the relationships that should govern the use of thermodynamics in fluid mechanics in a way that we believe is understandable to mathematicians. We also aim to better define the reasons why mechanics and thermodynamics must be correctly linked by showing that the principle of virtual work expressed using a specific internal energy is perfectly suited to fluid mechanics problems, provided that a well-chosen internal energy is proposed.
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Optics · Cross-listed from quant-ph
Tuning Wave-Particle Duality of Quantum Light by Generalized Photon Subtraction
Kan Takase, Mamoru Endo, Fumiya Hanamura et al. (+11 more)
Wave–particle duality is a hallmark of
quantum mechanics. For bosonic systems, there exists a continuum of intermediate states bridging wave-like Schrödinger cat states and particle-like Fock states. Such states have recently been recognized as valuable resources for enhancing fault-tolerant
quantum computation (FTQC) with propagating light. Here we experimentally demonstrate tunable generation of these intermediate states by employing generalized
photon subtraction (GPS). By detecting up to three
photons from squeezed-light sources with a
photon-number-resolving detector, we continuously control the balance between wave- and particle-like features. This approach allows us to construct a spectral family of
quantum states with high generation rates, optimized according to the required fault-tolerance threshold. Our results establish GPS as a versatile toolbox for tailoring non-Gaussian resources, opening a pathway to efficient Gottesman–Kitaev–Preskill (GKP)
qubit generation and addressing a central bottleneck in optical
quantum computing.
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All authors Kan Takase, Mamoru Endo, Fumiya Hanamura, Kazuki Hirota, Masahiro Yabuno, Hirotaka Terai, Shigehito Miki, Takahiro Kashiwazaki, Asuka Inoue, Takeshi Umeki, Petr Marek, Radim Filip, Warit Asavanant, Akira Furusawa