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Physics Physics

physics Watch Physics

Wednesday 5 November

Fluid Dynamics

Fast droplet impact onto slowly moving deep pools

Thomas C. Sykes, Luke F.L. Alventosa, J. Rafael Castrejon-Pita et al. (+3 more)

When a fast droplet impacts a pool, the resulting ejecta sheet dynamics determine the final impact outcome. At low Capillary numbers, the ejecta sheet remains separate from a deep static pool, whilst at higher viscosities it develops into a lamella. Here, we show that the common natural scenario of a slowly moving deep pool can change the upstream impact outcome, creating highly three-dimensional dynamics no longer characterised by a single descriptor. By considering how pool movement constrains the evolution of the ejecta sheet angle, we reach a length-scale invariant parameterisation for the upstream transition that holds for a wide range of fluids and impact conditions. Direct numerical simulations show similar dynamics for an equivalent oblique impact, indicating that the pool boundary layer does not play a decisive role for low pool-droplet speed ratios. Our results also provide insight into the physical mechanism that underpins pool impact outcomes more generally.
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All authors Thomas C. Sykes, Luke F.L. Alventosa, J. Rafael Castrejon-Pita, Radu Cimpeanu, Daniel M. Harris, Alfonso A. Castrejon-Pita

Biological Physics · Cross-listed from nlin.CD

Final state sensitivity and fractal basin boundaries from coupled Chialvo neurons

Bennett Lamb and Brandon B. Le

We investigate and quantify the basin geometry and extreme final state uncertainty of two identical electrically asymmetrically coupled Chialvo neurons. The system's diverse behaviors are presented, along with the mathematical reasoning behind its chaotic and nonchaotic dynamics as determined by the structure of the coupled equations. The system is found to be multistable with two qualitatively different attractors. Although each neuron is individually nonchaotic, the chaotic basin takes up the vast majority of the coupled system's state space, but the nonchaotic basin stretches to infinity due to chance synchronization. The boundary between the basins is found to be fractal, leading to extreme final state sensitivity. This uncertainty and its potential effect on the synchronization of biological neurons may have implications for understanding neuronal biology.
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Optics · Cross-listed from cond-mat.mes-hall

Gate-tunable single terahertz meta-atom ultrastrong light-matter coupling

Elsa Jöchl, Anna-Lydia Vieli, Lucy Hale et al. (+6 more)

We study the electrical tunability of ultrastrong light-matter interactions between a single terahertz circuit-based complementary split ring resonator (cSRR) and a two-dimensional electron gas. For this purpose, transmission spectroscopy measurements are performed under the influence of a strong magnetic field at different set points for the electric gate bias. The resulting Landau polariton dispersion depends on the applied electric bias, as the gating technique confines the electrons in-plane down to extremely sub-wavelength dimensions as small as d = 410 nm. This confinement allows for the excitation of standing plasma waves at zero magnetic field and an effective tunability of the electron number coupled to the THz resonator. This allows the normalized coupling strength to be tuned in-situ from $\eta$ = 0.46 down to $\eta$ = 0.18. This is the first demonstration of terahertz far-field spectroscopy of an electrically tunable interaction between a single terahertz resonator and electrons in a GaAs quantum well heterostructure.
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All authors Elsa Jöchl, Anna-Lydia Vieli, Lucy Hale, Felix Helmrich, Deniz Turan, Mona Jarrahi, Mattias Beck, Jérôme Faist, Giacomo Scalari

Fluid Dynamics · Cross-listed from cond-mat.stat-mech

Burgers dynamics for Poisson point process initial conditions

Patrick Valageas

We investigate the statistical properties of one-dimensional Burgers dynamics evolving from stochastic initial conditions defined by a Poisson point process for the velocity potential, with a power-law intensity. Thanks to the geometrical interpretation of the solution in the inviscid limit, in terms of first-contact parabolas, we obtain explicit results for the multiplicity functions of shocks and voids, and for velocity and density one- and two-point correlation functions and power spectra. These initial conditions gives rise to self-similar dynamics with probability distributions that display power-law tails. In the limit where the exponent $\alpha$ of the Poisson process that defines the initial conditions goes to infinity, the power-law tails steepen to Gaussian falloffs and we recover the spatial distributions obtained in the classical study by Kida (1979) of Gaussian initial conditions with vanishing large-scale power.
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Instrumentation and Detectors

High-$Q$ Superconducting Lumped-Element Resonators for Low-Mass Axion Searches

Roman Kolevatov, Saptarshi Chaudhuri and Lyman Page

Low-frequency superconducting lumped-element resonators have recently attracted significant attention in the context of axion dark matter searches. Here we present the design and implementation of a fixed-frequency superconducting resonator operating near 250 kHz, possessing an inductor volume of approximately 1 liter and achieving an unloaded quality factor $Q \approx 2.1\times10^{6}$. This resonator represents a significant improvement over the state of the art and informs the design of searches for low-mass axions.
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Computational Physics · Cross-listed from astro-ph.CO

Quantifying Weighted Morphological Content of Large-Scale Structures via Simulation-Based Inference

M. H. Jalali Kanafi and S. M. S. Movahed

We perform a simulation-based forecasting analysis to compare the cosmological constraining power of higher-order summary statistics of the large-scale structure, the Minkowski Functionals (MFs) and a class weighted morphological measure known as the Conditional Moments of Derivatives (CMD), with that of the redshift-space halo power spectrum multipoles (PS), with a particular focus on their sensitivity to nonlinear and anisotropic features in redshift space. Our analysis relies on halo catalogs from the Big Sobol Sequence simulations at redshift $z=0.5$, employing a likelihood-free inference framework implemented via neural posterior estimation. At the fiducial Quijote cosmology and for a Gaussian smoothing scale of $R=15\,h^{-1}\mathrm{Mpc}$, CMD provide systematically tighter constraints than MFs. Combining MFs and CMD into a joint estimator improves the precision by $27\%^{+9\%}_{-5\%}$ for $\sigma_8$ and $26\%^{+7\%}_{-5\%}$ for $\Omega_{\mathrm{m}}$ relative to MFs alone, highlighting the complementary anisotropy-sensitive information captured by the CMD in contrast to the scalar morphological content encapsulated by the MFs. We compare the combined statistic MFs+CMD with the PS at matched effective scales ($k_{\max}\simeq0.16\,h\,\mathrm{Mpc^{-1}}$) under three halo-selection conditions: all halos, fixed number density, and mass-selected ($M>3\times10^{13}\,h^{-1}M_\odot$). In the mass-selected configuration, the (weighted) morphological estimator outperforms the power spectrum by $45\%^{+20\%}_{-9\%}$ for $\sigma_8$ and $43\%^{+10\%}_{-7\%}$ for $\Omega_{\mathrm{m}}$. We also extend the simulation-based forecast analysis across a continuous range of cosmological parameters and multiple smoothing scales for morphological measures.
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Optics

Polarization conversion using hybrid near-zero and high-index metamaterials

Ben Johns, Hannes Kempf, Lakshmi Das et al. (+2 more)

Near-zero-refractive index materials display unique optical properties such as perfect transmission through distorted waveguides, cloaking, and inhibited diffraction. Compared to conventional media, they can fundamentally behave differently to light impinging from air, owing to the phenomenon of total external reflection. This makes them attractive for evanescent wave phenomena without prism coupling or sub-wavelength air gaps. Here, we introduce a strategy for linear-to-circular polarization conversion based on this effect. Practically realizable device designs are presented using hybrid structures of near-zero index and high index materials in a simple planar geometry. Our results predict polarization conversion in both reflection and transmission configurations based on naturally available epsilon-near-zero materials and illustrate the role of loss in limiting performance. Although the operation wavelength is limited to the epsilon-near-zero region, the concept can be implemented from the terahertz to optical domains using tunable epsilon-near-zero materials.
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All authors Ben Johns, Hannes Kempf, Lakshmi Das, Aitor De Andrés, Nicolò Maccaferri

Biological Physics

Exchange controls coarsening of surface condensates

Riccardo Rossetto, Marcel Ernst and David Zwicker

Biological membranes often exhibit heterogeneous protein patterns, which cells control. Strong patterns, like the polarity spot in budding yeast, can be described as surface condensates, formed by physical interactions between constituents. However, it is unclear how these interactions affect the material exchange with the bulk. To study this, we analyze a thermodynamically consistent model, which reveals that passive exchange generally accelerates the coarsening of surface condensates. Active exchange can further accelerate coarsening, although it can also fully arrest it and induce complex patterns involving various length scales. We reveal how these behaviors are related to non-local transport via diffusion through the bulk, rationalizing the various scaling laws we observe and allowing us to interpret biologically relevant scenarios.
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Fluid Dynamics

Disentangling Internal Tides from Balanced Motions with Deep Learning and Surface Field Synergy

Han Wang, Jeffrey Uncu, Kaushik Srinivasan et al. (+1 more)

A fundamental challenge in ocean dynamics is disentangling balanced motions and internal waves. Extracting internal tidal (IT) imprints from surface data is a central part of this challenge. Traditional harmonic analysis can fail under strong incoherence and poor temporal sampling, as in global satellite observations. New wide-swath satellites provide two-dimensional spatial coverage, allowing IT extraction to be reformulated as image translation. Building on our earlier deep-learning approach for extracting IT signatures from sea surface height (SSH) in an idealized turbulent simulation, we show that a simpler, computationally cheaper algorithm performs comparably in our experiments when the learning rate is annealed during training. Using this algorithm, we test different combinations of surface inputs: SSH, surface temperature, and surface velocity. All fields contribute synergistically to disentanglement in our deterministic benchmark, with surface velocity by far the most informative. These findings underscore the value of coordinated multi-platform observations and highlight the importance of surface velocity for separating balanced motions and internal waves. Additional analysis shows that both wave-signature information and scattering-medium information aid IT extraction. To exploit large-scale, mesoscale-reaching information in the scattering medium, the algorithm must be highly non-local. Residual errors concentrate at small spatial scales near mode-2 tidal wavelengths, likely reflecting incomplete input information, uncertainty in the simulation-derived reference fields, including possible Doppler-shift contamination, and limitations of the present deterministic architecture.
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All authors Han Wang, Jeffrey Uncu, Kaushik Srinivasan, Nicolas Grisouard

Computational Physics · Cross-listed from astro-ph.SR

Modelling the Solar Cycle Nonlinearities into the Algebraic Approach

Mohammed H. Talafha

Understanding and predicting solar-cycle variability requires accounting for nonlinear feedbacks that regulate the buildup of the Sun's polar magnetic field. We present a simplified but physically grounded algebraic approach that models the dipole contribution of active regions (ARs) while incorporating two key nonlinearities: tilt quenching (TQ) and latitude quenching (LQ). Using ensembles of synthetic cycles across the dynamo effectivity range $\lambda_R$, we quantify how these mechanisms suppress the axial dipole and impose self-limiting feedback. Our results show that (i) both TQ and LQ reduce the polar field, and together they generate a clear saturation (ceiling) of dipole growth with increasing cycle amplitude; (ii) the balance between LQ and TQ, expressed as $R(\lambda_R) = \mathrm{dev(LQ)}/\mathrm{dev(TQ)}$, transitions near $\lambda_R \approx 12^\circ$, with LQ dominating at low $\lambda_R$ and TQ at high $\lambda_R$; (iii) over $8^\circ \leq \lambda_R \leq 20^\circ$, the ratio follows a shallow offset power law with exponent $n \approx 0.36 \pm 0.04$, significantly flatter than the $n=2$ scaling assumed in many surface flux–transport (SFT) models; and (iv) symmetric, tilt-asymmetric, and morphology-asymmetric AR prescriptions yield nearly identical $R(\lambda_R)$ curves, indicating weak sensitivity to AR geometry for fixed transport. These findings demonstrate that nonlinear saturation of the solar cycle can be captured efficiently with algebraic formulations, providing a transparent complement to full SFT simulations. The method highlights that the LQ\–TQ balance is primarily controlled by transport ($\lambda_R$), not by active-region configuration, and statistically disfavors the SFT-based $1/\lambda_R^{2}$ dependence.
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Optics · Cross-listed from nlin.PS

Stability of the Quantum Coherent Superradiant States in Relation to Exciton-Phonon Interactions and the Fundamental Soliton in Hybrid Perovskites

A. A. Gladkij, N. A. Veretenov, N. N. Rosanov et al. (+3 more)

The use of macroscopic coherent quantum states at room temperature is crucial in modern quantum technologies. In light of recent experiments demonstrating high-temperature superfluorescence in hybrid perovskite thin films, in this work we investigate the stability of the superradiant state concerning exciton-phonon interactions, taking into account the specifics of perovskites. We focused on quasi-2D Wannier excitons interacting with longitudinal optical (LO) phonons in polar crystals, as well as with acoustic phonons. Our study leads to the derivation of nonlinear equations in the coordinate space that govern the exciton wavefunction's coefficient in the single-exciton basis for the lowest exciton state, which translates to the complex-valued polarization. The resulting equations take the form of a 2D nonlocal nonlinear Schrodinger (NLS) equation. We perform a linear stability analysis of the plane wave solutions for the equations in question, which allows us to establish stability criteria. This analysis is particularly important for evaluating the stability of the superradiant state in the considered quasi-2D structures, as the superradiant state represents a specific case of the plane wave solution. In scenarios involving the weakly nonlocal NLS equation, we find that it transitions into a purely nonlocal form. Furthermore, interactions between the exciton and acoustic phonons reduce the intensity of modulationally stable waves compared to the case without such interactions. Our analytical results are corroborated by numerical calculations. We also numerically solve the 2D nonlocal NLS equation in the polar coordinates and obtain its fundamental soliton solution, which is stable.
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All authors A. A. Gladkij, N. A. Veretenov, N. N. Rosanov, B. A. Malomed, V. Al. Osipov, B. D. Fainberg

Optics

Super-resolution Optical Near-field EM for bio- and materials science

Ilia Zykov, Guido Stam, Hanieh Jafarian et al. (+6 more)

Microscopy has been key to tremendous advances in science, technology, and medicine, revealing structure and dynamics across time and length scales. However, combining high spatial and temporal resolution in a non-invasive, label-free imaging technique remains a central challenge in microscopy. Here, we introduce Optical Near-field Electron Microscopy (ONEM), a method that converts optical near-field intensity patterns into photoelectron emission, enabling nanometer-scale imaging using low-energy electron microscopy. ONEM achieves 31 nm spatial and sub-second temporal resolution without exposing the sample to electrons, preserving structural and functional integrity. We demonstrate ONEM across three distinct domains: imaging polarization-dependent plasmon modes in metal nanostructures; visualizing live Escherichia coli in liquid with orientation-resolved contrast in 3D; and capturing real-time electrodeposition of copper nanoclusters from solution. These results establish ONEM as a versatile platform for damage-free super-resolution imaging of interface dynamics in both vacuum and liquid, with broad implications for biology, electrochemistry, and nanophotonics.
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All authors Ilia Zykov, Guido Stam, Hanieh Jafarian, Amin Moradi, Peter Neu, Rudolf Tromp, Mariana Amaro, Thomas Juffmann, Sense van der Molen

Optics · Cross-listed from quant-ph

Spontaneous symmetry breaking in nonlinear superradiance

Nikolai D. Klimkin and Misha Ivanov

Creation and manipulation of non-classical states of light is rapidly becoming the focus of modern attosecond science. Here, we demonstrate numerically how interaction with such states can trigger the emergence of a many-body system with spontaneously broken symmetry by considering a modification of the well-known problem of superradiance encountered already by Dicke. Similarly to him, we investigate photon emission by ensembles of indistinguishable atoms. In contrast to him, however, we leverage symmetry-based selection rules to suppress emission of single photons by single atoms. A steady state is therefore only reached following a spontaneous transition into a collective symmetry-broken state of atoms and photonic modes. This transition permanently locks the atomic dipoles to the quantum field experienced by the system at a particular instant, transforming the entire setup into a potent quantum sensor reproducing the phase of the recorded quantum fluctuation.
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Optics

2D Addressable Mid-infrared Metasurface Spatial Light Modulator

Cosmin-Constantin Popescu, Maarten Robbert Anton Peters, Oleg Maksimov et al. (+12 more)

Active metasurfaces enable dynamic control of light for applications in beam steering, pixelated holography, and adaptive optics, but demonstrations of two-dimensional (2D) electrically addressable arrays have so far been limited. Here we introduce a scalable 2D architecture based on phase-change materials (PCMs) integrated metasurfaces and apply it to realize the first transmissive mid-infrared (mid-IR) spatial light modulator (SLM). The device is fabricated through standard silicon photonic foundry processing combined with backend-of-line (BEOL) integration and employs multilayer backend metal interconnects to implement a crossbar addressing scheme. Each pixel is integrated with a silicon diode selector to suppress sneak-path currents, a feature essential for scaling to large arrays. The result establishes a foundry-compatible route to high-density, large-area active metasurfaces with independently tunable pixels.
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All authors Cosmin-Constantin Popescu, Maarten Robbert Anton Peters, Oleg Maksimov, Harish Bhandari, Rashi Sharma, Kathleen Richardson, Arka Majumdar, Hyun Jung Kim, Rui Chen, Khoi Phuong Dao, Luigi Ranno, Brian Mills, Dennis Calahan, Tian Gu, Juejun Hu

Chemical Physics

Encoding electronic ground-state information with variational even-tempered basis sets

Weishi Wang, Casey Dowdle and James D. Whitfield

We propose a system-oriented basis-set design based on even-tempered basis functions to variationally encode electronic ground-state information into molecular orbitals. First, we introduce a reduced formalism of concentric even-tempered orbitals that achieves hydrogen energy accuracy on par with the conventional formalism, with lower optimization cost and improved scalability. Second, we propose a symmetry-adapted, even-tempered formalism specifically designed for molecular systems. It requires only primitive S-subshell Gaussian-type orbitals and uses two parameters to characterize all exponent coefficients. In the case of the diatomic hydrogen molecule, the basis set generated by this formalism produces a dissociation curve more consistent with cc-pV5Z than cc-pVTZ at the size of aug-cc-pVDZ. Finally, we test our even-tempered formalism against several types of tetra-atomic hydrogen molecules for ground-state computation and point out its current limitations and potential improvements.
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Instrumentation and Detectors

Radiation Tolerance Characterisation of an Indigenously Developed p-type Silicon Pad Sensor for Forward Calorimetry Applications

Arun Kumar Yadav, Sanjib Muhuri, Anup Kumar Sikdar et al. (+7 more)

We report on the radiation tolerance characterisation of a p-type silicon pad sensor indigenously designed by BARC-VECC and fabricated at Bharat Electronics Limited (BEL), India – representing a significant step toward establishing a domestic silicon sensor manufacturing capability for high-energy physics applications. Single-pad test structures were irradiated with neutrons over a range of fluences from $\sim10^{7}$ to $\sim2.5\times10^{14}$~1~MeV~$n_{\mathrm{eq}}$/cm$^{2}$, spanning the operational regime relevant to forward calorimetry in high-luminosity heavy-ion collider experiments. Post-irradiation performance was characterised through systematic measurement of leakage current evolution and calorimetric response as functions of accumulated neutron fluence. A single-exponential annealing model is introduced to describe the time dependence of leakage current within the observation window, and the current-related damage constant $\alpha$ is extracted and compared with the RD48 reference value. The results demonstrate that the sensors survive the target fluence with measurable but recoverable degradation, validating the fabrication process and providing a baseline for future qualification of this indigenous sensor production chain.
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All authors Arun Kumar Yadav, Sanjib Muhuri, Anup Kumar Sikdar, Subikash Choudhury, Sourav Mukhopadhyay, Jogender Saini, Mitul Abhangi, Ratnesh Kumar, Sudhirsinh Vala, Zubayer Ahammed

Chemical Physics

Efficient Implementation of the Spin-Free Renormalized Internally-Contracted Multireference Coupled Cluster Theory

Kalman Szenes, Riya Kayal, Kantharuban Sivalingam et al. (+3 more)

In this paper, an efficient implementation of the renormalized internally-contracted multreference coupled cluster with singles and doubles (RIC-MRCCSD) into the ORCA quantum chemistry program suite is reported. To this end, Evangelista's Wick&d equation generator was combined with ORCA's native AGE code generator in order to implement the many-body residuals required for the RIC-MRCCSD method. Substantial efficiency gains are realized by deriving a spin-free formulation instead of the previously reported spin-orbital version developed by some of us. Since AGE produces parallelized code, the resulting implementation can directly be run in parallel with substantial speedups when executed on multiple cores. In terms of runtime, the cost of RIC-MRCCSD is shown to be between single-reference RHF-CCSD and UHF-CCSD, even when active space spaces as large as CAS(14,14) are considered. This achievement is largely due to the fact that no reduced density matrices (RDM) or cumulants higher than three-body enter the formalism. The scalability of the method to large systems is furthermore demonstrated by computing the ground-state of a vitamin B12 model comprised of an active space of CAS(12, 12) and 809 orbitals. In terms of accuracy, RIC-MRCCSD is carefully compared to second- and approximate fourth-order $n$-electron valence state perturbation theories (NEVPT2, NEVPT4(SD)), to the multireference zeroth-order coupled-electron pair approximation (CEPA(0)), as well as to the IC-MRCCSD from Kohn. In contrast to RIC-MRCCSD, the IC-MRCCSD equations are entirely derived by AGE using the conventional projection-based approach, which, however, leads to much higher algorithmic complexity than the former as well as the necessity to calculate up to the five-body RDMs. Remaining challenges such as the variation of the results with the flow, a free parameter that enters the RIC-MRCCSD theory, are discussed.
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All authors Kalman Szenes, Riya Kayal, Kantharuban Sivalingam, Robin Feldmann, Frank Neese, Markus Reiher

Applied Physics

ENDF/B-VIII.1: Updated Nuclear Reaction Data Library for Science and Applications

G.P.A. Nobre, R. Capote, M.T. Pigni et al. (+106 more)

The ENDF/B-VIII.1 library is the newest recommended evaluated nuclear data file by the Cross Section Evaluation Working Group (CSEWG) for use in nuclear science and technology applications, and incorporates advances made in the six years since the release of ENDF/B-VIII.0. Among key advances made are that the $^{239}$Pu file was reevaluated by a joint international effort and that updated $^{16,18}$O, $^{19}$F, $^{28-30}$Si, $^{50-54}$Cr, $^{55}$Mn, $^{54,56,57}$Fe, $^{63,65}$Cu, $^{139}$La, $^{233,235,238}$U, and $^{240,241}$Pu neutron nuclear data from the IAEA coordinated INDEN collaboration were adopted. Over 60 neutron dosimetry cross sections were adopted from the IAEA's IRDFF-II library. In addition, the new library includes significant changes for $^3$He, $^6$Li,$^9$Be, $^{51}$V, $^{88}$Sr, $^{103}$Rh, $^{140,142}$Ce, Dy, $^{181}$Ta, Pt, $^{206-208}$Pb, and $^{234,236}$U neutron data, and new nuclear data for the photonuclear, charged-particle and atomic sublibraries. Numerous thermal neutron scattering kernels were reevaluated or provided for the very first time. On the covariance side, work was undertaken to introduce better uncertainty quantification standards and testing for nuclear data covariances. The significant effort to reevaluate important nuclides has reduced bias in the simulations of many integral experiments with particular progress noted for fluorine, copper, and stainless steel containing benchmarks. Data issues hindered the successful deployment of the previous ENDF/B-VIII.0 for commercial nuclear power applications in high burnup situations. These issues were addressed by improving the $^{238}$U and $^{239,240,241}$Pu evaluated data in the resonance region. The new library performance as a function of burnup is similar to the reference ENDF/B-VII.1 library. The ENDF/B-VIII.1 data are available in ENDF-6 and GNDS format at https://doi.org/10.11578/endf/2571019.
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All authors G.P.A. Nobre, R. Capote, M.T. Pigni, A. Trkov, C.M. Mattoon, D. Neudecker, D.A. Brown, M.B. Chadwick, A.C. Kahler, N.A. Kleedtke, M. Zerkle, A.I. Hawari, C.W. Chapman, N.C. Fleming, J.L. Wormald, K. Ramić, Y. Danon, N.A. Gibson, P. Brain, M.W. Paris, G.M. Hale, I.J. Thompson, D.P. Barry, I. Stetcu, W. Haeck, A.E. Lovell, M.R. Mumpower, G. Potel, K. Kravvaris, G. Noguere, J.D. McDonnell, A.D. Carlson, M. Dunn, T. Kawano, D. Wiarda, I. Al-Qasir, G. Arbanas, R. Arcilla, B. Beck, D. Bernard, R. Beyer, J.M. Brown, O. Cabellos, R.J. Casperson, Y. Cheng, E.V. Chimanski, R. Coles, M. Cornock, J. Cotchen, J.P.W. Crozier, D.E. Cullen, A. Daskalakis, M.-A. Descalle, D.D. DiJulio, P. Dimitriou, A.C. Dreyfuss, I. Durán, R. Ferrer, T. Gaines, V. Gillette, G. Gert, K.H. Guber, J.D. Haverkamp, M.W. Herman, J. Holmes, M. Hursin, N. Jisrawi, A.R. Junghans, K.J. Kelly, H.I. Kim, K.S. Kim, A.J. Koning, M. Koštál, B.K. Laramee, A. Lauer-Coles, L. Leal, H.Y. Lee, A.M. Lewis, J. Malec, J.I. Márquez Damián, W.J. Marshall, A. Mattera, G. Muhrer, A. Ney, W.E. Ormand, D.K. Parsons, C.M. Percher, V.G. Pronyaev, A. Qteish, S. Quaglioni, M. Rapp, J.J. Ressler, M. Rising, D. Rochman, P.K. Romano, D. Roubtsov, G. Schnabel, M. Schulc, G.J. Siemers, A.A. Sonzogni, P. Talou, J. Thompson, T.H. Trumbull, S.C. van der Marck, M. Vorabbi, C. Wemple, K.A. Wendt, M. White, R.Q. Wright

Computational Physics · Cross-listed from quant-ph

Atom-Field Non-Markovian Dynamics in Open and Dissipative Systems: An Efficient Memory-Kernel Approach Linked to Dyadic Greens Function and CEM Treatments

Hyunwoo Choi, Jisang Seo, Weng C. Chew et al. (+1 more)

In this work, we present a numerical framework for modeling single photon emission from a two level system in open and dissipative systems beyond the Markovian approximation. The method can be readily integrated into standard computational electromagnetic (CEM) solvers such as finite difference time domain (FDTD) and finite element method (FEM). We numerically verify the completeness of boundary and medium assisted modes in the modified Langevin noise formalism by reconstructing the imaginary part of the dyadic Greens function through modal expansion in three dimensions. This reconstruction enables a first principles description of atom field interaction via the multi mode Jaynes Cummings model in open and dissipative environments. Within the single excitation manifold, we show that the memory kernel of a two level system is determined by the imaginary part of the Greens function, implying that radiative modes alone govern the relevant dynamics. The proposed framework thus provides a Greens function based approach for describing atomic population and single photon dynamics, directly compatible with Maxwell solvers. We then present concrete strategies for implementing our method in both FDTD and FEM frameworks, demonstrating its practical applicability. We further verify numerical results for a lossy Lorentz Drude type mirror, including both the case of a TLS near a finite sized metallic mirror and that of a TLS centered in a Fabry Perot cavity. This work establishes a rigorous foundation for incorporating quantum emitter dynamics into computational electromagnetics, thereby extending classical solvers toward quantum light matter interactions.
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All authors Hyunwoo Choi, Jisang Seo, Weng C. Chew, Dong-Yeop Na

Optics

Mie-tronics supermodes and symmetry breaking in nonlocal metasurfaces

Thanh Xuan Hoang, Ayan Nussupbekov, Jie Ji et al. (+3 more)

It is usually believed that symmetry breaking in photonic systems leads to weaker optical confinement, such as in the case of metasurfaces when bound states in the continuum are replaced by quasi-bound states with lower quality factors (Q factors). Here we show that symmetry breaking can instead enhance light trapping by strengthening in-plane nonlocal coupling pathways. We consider finite-size arrays of optical resonators supporting Mie resonances (a Mie-tronics platform) and employ diffraction and multiple-scattering analyses. We demonstrate that diffractive bands and Mie-tronics supermodes originate from the same underlying Mie resonances but differ fundamentally in their physical nature. Finite arrays exhibit Q-factor enhancement driven by redistributed radiation channels, and reversing the trends predicted by infinite-lattice theories. We reveal that controlled symmetry breaking opens new electromagnetic coupling channels, enabling polarization conversion in nonlocal metasurfaces. These novel findings establish a unified wave-physics platform linking both scattering and diffraction theories. Also, they outline the design principles for multi-functional metasurfaces that exploit nonlocality for advanced light manipulation, computation, and emission control.
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All authors Thanh Xuan Hoang, Ayan Nussupbekov, Jie Ji, Daniel Leykam, Jaime Gomez Rivas, Yuri Kivshar

Chemical Physics · Cross-listed from quant-ph

Quantum error mitigation using energy sampling and extrapolation enhanced Clifford data regression

Zhongqi Zhao, Erik Rosendahl Kjellgren, Sonia Coriani et al. (+3 more)

Error mitigation is essential for the practical implementation of quantum algorithms on noisy intermediate-scale quantum (NISQ) devices. This work explores and extends Clifford Data Regression (CDR) to mitigate noise in quantum chemistry simulations using the Variational Quantum Eigensolver (VQE). Using the H$_4$ molecule with the tiled Unitary Product State (tUPS) ansatz, we perform noisy simulations with the ibm torino noise model to investigate in detail the effect of various hyperparameters in CDR on the error mitigation quality. Building on these insights, two improvements to the CDR framework are proposed. The first, Energy Sampling (ES), improves performance by selecting only the lowest-energy training circuits for regression, thereby further biasing the sample energies toward the target state. The second, Non-Clifford Extrapolation (NCE), enhances the regression model by including the number of non-Clifford parameters as an additional input, enabling the model to learn how the noisy-ideal mapping evolves as the circuit approaches the optimal one. Our numerical results demonstrate that both strategies outperform the original CDR.
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All authors Zhongqi Zhao, Erik Rosendahl Kjellgren, Sonia Coriani, Jacob Kongsted, Stephan P. A. Sauer, Karl Michael Ziems

Chemical Physics

Group 13 Metals as L-Type Ligands for Transition Metals

Hellen Videa, M. Angeles Fuentes and Antonio J. Martinez-Martinez

Low-valent Group 13 fragments can serve as neutral two-electron L-type metalloligands to transition-metal (TM) centers, enabling heterometallic M-TM platforms with bonding and reactivity patterns distinct from classical CO, phosphine, and carbene ligation. This chapter develops a unifying, descriptor-based view of aluminylene Al(I), gallylene Ga(I), and indylene In(I) donors, and contrasts them with the limited L-type behavior of Tl(I). We map synthetic gateways to isolable M(I) donors, analyze their sigma-donation/pi-acceptance profiles, and extract periodic design rules in which the sigma-donor strength decreases Al > Ga > In, whereas Tl(I) has not yet been convincingly shown to engage in neutral L-type Tl->TM coordination. Borderline cases that blur L-, X-, and Z-type classifications are also examined to clarify descriptors and guide consistent usage across the series. This contribution links ligand sterics/electronics, ambiphilicity at M(I), and the chosen TM fragment to guide the rational design of M-TM platforms that harness Group-13 M(I) donors for small-molecule activation and cooperative catalysis.
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2511.03513 · 5 Nov · Preprint (107 pages, 59 figures). Submitted to Springer Nature (Structure and Bonding: Transition Metal-Main Group Heterobimetallics). This is the author's original manuscript, pre-acceptance and not peer-reviewed. The final authenticated version, once published, will be available at SpringerLink with its DOI; please cite the Version of Record when available

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Accelerator Physics

Beam Cleaning and Collimation Systems

Stefano Redaelli

Collimation systems in particle accelerators are designed to safely and efficiently dispose of unavoidable beam losses during operation. Their specific roles vary depending on the type of accelerator. The state of the art in hadron beam collimation for high-intensity, high-energy superconducting colliders is exemplified by the system implemented at the CERN Large Hadron Collider (LHC). In this machine, the stored beam energy reaches levels several orders of magnitude higher than the tiny energy required to quench superconducting magnets. It also exceeds by orders of magnitude the damage thresholds of typical accelerator components, placing stringent demands on beam loss control. Collimation systems are therefore essential for the reliable daily operation of modern accelerators. This lecture reviews the design of a multistage collimation system, using the LHC as a case study. The LHC collimation system has achieved unprecedented cleaning performance, with a level of complexity unmatched by any other accelerator. Design aspects and operational challenges of such large-scale collimation systems are also discussed.
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Biological Physics · Cross-listed from q-bio.NC

Emergent tuning heterogeneity in cortical circuits is sensitive to cellular neuronal dynamics

Mohammadreza Soltanipour, Stefan Treue and Fred Wolf

Cortical circuits exhibit high levels of response diversity, even across apparently uniform neuronal populations. While emerging data-driven approaches exploit this heterogeneity to infer effective models of cortical circuit computation (e.g. Genkin et al. Nature 2025), the power of response diversity to enable inference of mechanistic circuit models is largely unexplored. Within the landscape of cortical circuit models, spiking neuron networks in the balanced state naturally exhibit high levels of response and tuning diversity emerging from their internal dynamics. A statistical theory for this emergent tuning heterogeneity, however, has only been formulated for binary spin models (Vreeswijk & Sompolinsky, 2005). Here we present a formulation of feature-tuned balanced state networks that allows for arbitrary and diverse dynamics of postsynaptic currents and variable levels of heterogeneity in cellular excitability but nevertheless is analytically exactly tractable with respect to the emergent tuning curve heterogeneity. Using this framework, we present a case study demonstrating that, for a wide range of parameters even the population mean response is non-universal and sensitive to mechanistic circuit details. As our theory enables exactly and analytically obtaining the likelihood-function of tuning heterogeneity given circuit parameters, we argue that it forms a powerful and rigorous basis for neural circuit inference.
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Space Physics · Cross-listed from astro-ph.SR

Evolution of the Shock Properties of the 2023 March 13 Event from In-Situ and Remote-Sensing Data

Federica Chiappetta, Giuseppe Nisticò, Massimo Chimenti et al. (+6 more)

Shocks driven by coronal mass ejections (CMEs) are the most powerful accelerators of gradual solar energetic particles (SEPs) in the inner heliosphere. On 2023 March 13, a halo CME, as seen from the Solar Heliospheric Observatory (SoHO) and the Sun TErrestrial Relations Observatory (STEREO), gave rise to a strong SEP event. In this work, we aim to analyze this CME-driven shock from multiple spacecraft, using both remote sensing observations from STEREO-A/COR2 and in-situ data from Parker Solar Probe (PSP), Solar Orbiter (SolO), and Wind. In order to determine its direction of propagation and kinematic properties, we model the shock geometry using STEREO-A/COR2 and SoHO/LASCO/C3 observations as an expanding ellipsoid. The density compression ratio of the shock is determined by fitting the brightness profile from the coronagraphic images with that obtained from raytracing simulations of a double-Gaussian shock density profile. We compare physical quantities such as compression ratio and Alfvénic Mach number derived from remote sensing observations with in-situ measurements by PSP, SolO, STEREO-A, and Wind. From STEREO-A/COR2, we determine the compression ratio around the entire shock front in the corona, finding significant non-homogeneities that can impact the values found during in-situ crossings. Following the evolution of the parameters characterizing the CME from the source to space, we find that closer to the Sun, both the gas compression ratio and the Alfvénic Mach number remain almost constant, while they increase at larger radial distances. This indicates a non-trivial evolution of the shock parameters during its journey through the interplanetary space.
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All authors Federica Chiappetta, Giuseppe Nisticò, Massimo Chimenti, Andrea Larosa, Francesco Malara, Francesco Pucci, Luca Sorriso-Valvo, Gaetano Zimbardo, Silvia Perri

Medical Physics

Performance Evaluation of a Position-Sensitive SiPM-based Gamma Camera for Intraoperative Imaging

Aramis Raiola, Fabio Acerbi, Cyril Alispach et al. (+4 more)

The POSiCS camera is a handheld, small field-of-view gamma camera developed for multipurpose use in radio-guided surgery (RGS), with sentinel lymph node biopsy (SLNB) as its benchmark application. This compact and lightweight detector (weighing approximately 350 g) can map tissues labeled with Tc-99m nanocolloids and guide surgeons to the location of target lesions. By enabling intraoperative visualization in close proximity to the surgical field, its primary objective is to minimize surgical interventional invasiveness and operative time, thereby enhancing localization accuracy and reducing the incidence of post-operative complications. The design and components of the POSiCS camera emphasize ergonomic handling and compactness, providing, at the same time, rapid image formation and a spatial resolution of a few millimeters. These features are compatible with routine operating-room workflow, including wireless communication with the computer and a real-time display to support surgeon decision-making. The spatial resolution measured at a source-detector distance of 0 cm was 1.9 +/- 0.1 mm for the high-sensitivity mode and 1.4 +/- 0.1 mm for the high-resolution mode. The system sensitivity at 2 cm was evaluated as 481 +/- 14 cps/MBq (high sensitivity) and 134 +/- 8 cps/MBq (high resolution). For both working modes, we report an energy resolution of approximately 20 percent, even though the high-resolution collimator exhibits an increased scattered component due to the larger amount of tungsten.
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All authors Aramis Raiola, Fabio Acerbi, Cyril Alispach, Domenico della Volpe, Hossein Arabi, Alberto Gola, Habib Zaidi

Optics

Resonant states reveal strong light-matter coupling in nanophotonic cavities

Jan David Fischbach, Sergei Gladyshev, Adrià Canós Valero et al. (+3 more)

Photonic resonances enable control over light-matter interactions, but many key phenomena only emerge in the strong-coupling regime where light and matter excitations fully hybridize. To distinguish between weak and strong coupling, one conventionally studies real-frequency spectra of the hybrid system. However, these spectra only provide indirect estimates of the underlying resonant dynamics, as the resonances reside at complex frequencies. To overcome this contradiction, we demonstrate that photonic resonant states provide a framework for unambiguously distinguishing between weak and strong coupling. Upon tracing the resonant states through the complex plane while changing the resonator geometry, their trajectories undergo a qualitative change at the onset of strong coupling. Instead of passing each other in the complex frequency plane with only perturbative interactions, the resonant states swap positions. Assuming a single dominant photonic resonance, we derive an effective Hamiltonian that captures the interaction with multiple material resonances, including direct access to coupling rates from overlap-integrals. Our analysis reveals that, unlike most coupled-oscillator models commonly employed, hybridization not only introduces off-diagonal coupling but also shifts the bare eigenfrequency of the photonic mode. We apply our approach to planar and spherical silver resonators filled with a molecular material whose properties were extracted from quantum-chemical simulations.
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All authors Jan David Fischbach, Sergei Gladyshev, Adrià Canós Valero, Markus Nyman, Thomas Weiss, Carsten Rockstuhl

Physics and Society

Cost Reducing Adiabatic Compressed Air Energy Storage for Long Duration Energy Storage Applications

Danlei Yang, Yang Wang, Jihong Wang et al. (+2 more)

Long-duration energy storage (LDES) is vital for decarbonizing the energy system but faces economic challenges, including high upfront costs, low trading frequency, and limited revenue in current electricity markets. Compressed Air Energy Storage (CAES) is a promising LDES solution, though its economic viability, especially for long storage durations beyond lithium-ion battery capabilities, remains unclear. To address this, here we compiled and analyzed a global emerging adiabatic CAES cost database, showing a continuous cost reduction with an experience rate of 15% as capacities scaled from 10MW to 100MW. Our lifecycle discounted cash flow analysis suggests that adiabatic CAES could achieve economic viability for 10-100 hour storage durations, particularly with optimal geological siting to lower storage costs. This economically viable LDES option will enable large-scale grid balancing and support renewable integration over multi-day periods, making it a valuable asset for advancing deep decarbonization of energy systems.
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All authors Danlei Yang, Yang Wang, Jihong Wang, Zhenhua Rui, Wei He

Fluid Dynamics

Spatiotemporal statistics of the dissipation rate at the boundary of a turbulent flow using Diffusing-Wave Spectroscopy

Enzo Francisco, Julien Lambret and Sébastien Aumaître

We use Diffusing Wave Spectroscopy (DWS) to perform the first direct space- and time-resolved measurement of the dissipation rate~$\epsilon$ at the boundary of a turbulent flow. We have shown in a previous publication that this technique provides maps of the dissipation rate of Newtonian fluids~\cite{Francisco}. Here, we apply the technique at the boundary of a turbulent flow generated in a square box by an impeller stirring the fluids. Although the measurement is made on a small region near the boundary, we show that the dissipation remains proportional to the injected power and follows the turbulent scaling $\epsilon \propto \mathrm{Re}^3$, with Re being the Reynolds number ranging from $1.5 \times 10^4$ to $6 \times 10^5$. With this flow, there is no need for logarithmic corrections to reproduce the dissipation near the flat boundary. In addition, our setup allows us to measure the spatio-temporal fluctuations of the dissipation near the boundary. These fluctuations are quite large (the relative fluctuations are about 50%) and are well described by a log-normal distribution, as expected for the dissipation rate in the bulk of homogeneous and isotropic turbulence (HIT) but Power Density Spectra (PDS) do not correspond to those expected for HIT \cite{Li07,Graham16,K62}
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Space Physics

Rebound Suppression Mechanisms of Particle-Filled Flexible Shells for Small Body Landings

Tongge Wen, Xiaoyu Yang, Sudeshna Roy et al. (+2 more)

The extremely weak gravity on small bodies makes landers prone to rebound and uncontrolled drift. To mitigate this, the Hayabusa2 mission employed a particle-filled flexible shell, but the coupled dynamics of shell deformation and internal particle dissipation remain unclear. We develop a computational model representing the flexible shell as a spring-mass network and fully resolve particle collisions, friction, and interactions with granular beds. Results show the flexible shell-granule system dissipates over 90 percent of impact energy, far exceeding rigid shells. Energy loss arises from shell-particle coupling, with the particle filling ratio dominating. Impacts on rigid planes produce large shell deformation, while granular beds limit deformation. Scaling and velocity analyses reveal distinct dissipation regimes. These findings clarify energy transfer mechanisms and inform the design of microgravity impact mitigation devices.
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All authors Tongge Wen, Xiaoyu Yang, Sudeshna Roy, Thorsten Pöschel, Xiangyuan Zeng