Optics · Cross-listed from quant-ph
2D quantum-path interference in high-harmonic generation driven by highly-bichromatic fields
Xiaozhou Zou, Lucie Jurkovičová, Anne Weber et al. (+12 more)
We experimentally observe a new type of
quantum-path interference, in two-dimensions (2D-QPI), in high-harmonic generation (HHG) driven by an orthogonally-polarised highly-bichromatic field. This regime is marked by comparable intensities of the two orthogonal colours. In this highly-bichromatic regime, we demonstrate that 2D-QPI is encoded in the measured harmonic intensity modulations with respect to the relative phase of the two-colour field. The modulations of the odd-order harmonics show a monomodal behaviour, whereas the even harmonics are modulated in a bimodal structure. Our calculations using the strong-field approximation and saddle-point method disentangle contributions from multiple
quantum orbits in this HHG regime, revealing that the dipole response for both odd and even harmonics inherits the dynamic
symmetry of the orthogonally-polarised driving field. This new type of 2D-QPI offers a novel route to HHG spectroscopy of attosecond electron dynamics by lifting up the dimensionality of the
quantum paths involved in the interference.
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All authors Xiaozhou Zou, Lucie Jurkovičová, Anne Weber, Cong Zhao, Martin Albrecht, Ondřej Finke, Alexandr Vendl, Annika Grenfell, Wojciech Szuba, Jaroslav Nejdl, Eric Constant, Margarita Khokhlova, Emilio Pisanty, Ondřej Hort, Amelle Zaïr
Computational Physics · Cross-listed from cond-mat.mtrl-sci
All optical ultrafast pure spin current in the altermagnet Cr$_2$SO
Deepika Gill, Ruikai Wu, Peter Elliott et al. (+2 more)
All-optical generation of pure
spin current – the flow of
spin in the absence of a corresponding charge flow – relies on a
symmetry based compensation of valley charge. The 2d $d$-wave altermagnets, ideal spintronics materials due to a very low
spin-orbit coupling, possess a
magnetic point group and highly anisotropic valley
manifolds that would appear to preclude such current compensation, excluding them as materials for the ultrafast generation of pure
spin current. Here we show that infra-red valley excitation combined with a THz pulse envelope allows the generation of large and nearly 100% pure
spin currents in the altermagnet Cr$_2$SO. Our approach is based on a valley selection rule coupling linearly polarized light to
spin opposite valleys, along with the intrinsic momentum shift that a co-occurring THz pulse imbues a valley
spin excitation with. These results thus provide a practical and all-optical route to the generation of pure
spin current in $d$-wave 2d altermagnets, opening a route to lightwave control of
spin in an environment with very low intrinsic
spin mixing.
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All authors Deepika Gill, Ruikai Wu, Peter Elliott, Sangeeta Sharma, Sam Shallcross
Optics
Low-confinement silicon nitride waveguides manufactured via direct glass bonding
Mikhail V. Tsvetkov, Dmitry V. Obydennov, Alexandr S. Rykov et al. (+6 more)
Reducing the fabrication cost of photonic integrated
circuits while maintaining low optical losses and technological simplicity is essential for their wider implementation. In conventional manufacturing methods, the dielectric cladding thickness around waveguides is usually limited to $\sim20$~$\mu$m, which complicates suppression of radiative losses and parasitic scattering in low-confinement geometries. In this paper, we propose and experimentally demonstrate an alternative technology for forming low-confinement waveguides in Borofloat~33 glass by thermal fusion bonding of two glass wafers. The waveguide pattern is formed by etching trenches with depths on the order of tens of nanometers into the glass, filling them with silicon nitride, removing the excess layer, and bonding the planarized glass surfaces, thereby forming a thick, symmetric dielectric cladding. As a proof of concept, we fabricated straight waveguides with a core height of 50~nm and widths from 1.3 to 3.5~$\mu$m. With butt coupling to standard SMF-28 single-mode fiber at 1550~nm, we obtained chip transmissions up to 60%, corresponding to input/output coupling losses of $\sim1$~dB per facet and consistent with numerical estimates. Fabry–Perot analysis of high-resolution spectra measured with AR-coated lensed fibers gave effective propagation losses down to $0.62\pm0.36$ dB/cm, depending on waveguide width and polarization. The proposed approach provides a simple and scalable route to low-confinement glass-encapsulated photonic
circuits with passive butt coupling, promising for long delay lines, external-cavity
laser feedback
circuits, and ring-resonator sensors.
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All authors Mikhail V. Tsvetkov, Dmitry V. Obydennov, Alexandr S. Rykov, Alexandr R. Shevchenko, Maxim V. Shibalov, Ivan A. Filippov, Stepan D. Perov, Nikita Yu. Dmitriev, Michael A. Tarkhov
Data Analysis and Statistics · Cross-listed from gr-qc
Spectroscopy of analogue black holes using simulation-based inference
Leonardo Solidoro, Sebastian H. Völkel and Silke Weinfurtner
The emergence of precision
gravity simulators in
quantum and fluid systems is opening new avenues for probing curved-spacetime physics and black-hole phenomenology under controlled laboratory conditions. In parallel, advances in understanding how fundamental physics can be probed in the spectral signatures of black holes and exotic compact objects motivate the development of modern spectroscopic techniques within analogue-
gravity experiments. In this work, we model the spectral properties of analogue black holes sourced by broadband
stochastic noise, a crucial aspect in realistic experiments that poses substantial challenges for established data-analysis techniques. Using simulation-based inference, we demonstrate that the physical parameters encoded in noisy spectra can be reliably extracted, showing that these techniques provide a powerful tool for studying both spacetime properties and boundary effects in
gravity simulators.
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Fluid Dynamics
Long-time turbulence prediction at fine time steps using multi-stride neural operators
Guanyu Pan, Huiyu Yang, Yunpeng Wang et al. (+3 more)
Long-time
turbulence prediction at fine time steps is costly and prone to error accumulation, while accurate short-term fields do not ensure accurate long-time statistics. We propose a multi-stride neural operator for three-dimensional
turbulence, combining implicit factorized
Transformer (IFF) predictors with a factorized-
attention cross-stride fusion (FA-CSF) module. All predictors take the same current velocity field as input. FA-CSF reuses their outputs and latent features to generate intermediate velocity fields through interpolation and learned correction. The corrected largest-stride field drives the next autoregressive step, decoupling the autoregressive step from the output time step. Stride-conditioned IFF (SC-IFF) predictors are first trained at power-of-two strides using three conditioning strategies, then frozen while FA-CSF is trained on long rollouts with field-data and statistical losses. Tests on turbulent channel flow and forced homogeneous isotropic
turbulence (HIT) show improved long-time predictions and statistics. At a sampling interval of 10 direct numerical simulation (DNS) time steps, fixed-stride IFF yields relative L2 errors above 100% in channel-flow root-mean-square (RMS) velocity fluctuation profiles and the Reynolds shear stress profile, and in the temporal
evolution of velocity and vorticity RMS values and the time-averaged energy spectrum in HIT. SC-IFF with independent stride-specific predictors and FA-CSF keeps statistics close to filtered DNS data over the tested prediction times. Relative to fixed-stride IFF, it reduces errors in the channel-flow profiles by more than 98% and in the HIT spectrum by more than 99%. Multi-stride prediction with FA-CSF generates trajectories at fine time steps 3.69 times faster than fixed-stride IFF autoregression and 2.41 times faster than hierarchical multi-stride prediction.
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All authors Guanyu Pan, Huiyu Yang, Yunpeng Wang, Zikun Xu, Nianyu Yi, Jianchun Wang
Fluid Dynamics
Shape of an interface hit by an oblique jet
Theophile Gaichies, Anniina Salonen, Arnaud Antkowiak et al. (+1 more)
We report on the shape taken by the interface of a
liquid bath when hit by a smooth oblique steady jet. When the angle between the jet and the bath decreases below $50^\circ$, a cavity is formed in front of the jet. In the inertial regime we explore, the jet boundary layer detaches in the impact region, thereby delimiting a core jet region outside of which the
liquid is mainly in hydrostatic
equilibrium. The shape of the outer meniscus is shown to be related to the one outside a tilted fiber piercing the fluid interface. In order to unravel the flow features and separation, we perform direct numerical simulations and show that the flow detachment displays an asymmetry, which results in the acceleration of the
liquid below the surface, thereby creating a depression. With this observation, we propose a model balancing the suction force of this depression with the weight of the displaced water and the surface tension force to obtain a prediction for the typical width of the cavity.
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All authors Theophile Gaichies, Anniina Salonen, Arnaud Antkowiak, Emmanuelle Rio
Optics
Engineering strong coupling in ultra-compact photonic crystal/2D material platforms
Eleonora P. Kraus, Jamie M. Fitzgerald, Carlos Maciel-Escudero et al. (+1 more)
Sub-wavelength thick photonic
crystal (PhC) slabs coupled to 2D excitonic materials, such as transition metal dichalcogenides (TMDs), are a promising platform for highly tunable, room-temperature, on-chip optoelectronic devices. Unlike conventional Fabry-Perot microcavities, these compact open cavities exhibit non-trivial electric field profiles, leading to spatially distinct regions of weak and strong coupling with
excitons within the PhC unit
cell. Using coupled mode theory and rigorous solutions to Maxwell's equations, we investigate how the PhC geometry can be used to control these coexisting
exciton/polariton contributions and tailor the resulting optical spectra. For large filling factors, i.e., small air gaps, we show that PhC polaritons can be modeled as dark waveguide modes brightened via the periodicity of the PhC slab. Furthermore, by spatially patterning the TMD monolayer based on the local field intensity, we reveal the simultaneous presence of
excitons in both the weak and strong coupling regimes. Overall, this work provides fundamental insights into the strong light-matter coupling regime in structured photonic environments, offering a pathway to design and optimize metal-free, ultra-compact polaritonic devices.
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All authors Eleonora P. Kraus, Jamie M. Fitzgerald, Carlos Maciel-Escudero, Ermin Malic
Medical Physics
DoseRAD2026 Challenge dataset: AI accelerated photon and proton dose calculation for radiotherapy
Fan Xiao, Nikolaos Delopoulos, Niklas Wahl et al. (+13 more)
Purpose: Accurate dose calculation is essential in radiotherapy for precise tumor irradiation while sparing healthy tissue. With the growing adoption of MRI-guided and real-time adaptive radiotherapy, fast and accurate dose calculation on CT and MRI is increasingly needed. The DoseRAD2026
dataset and challenge provide a public
benchmark of paired CT and MRI data with beam-level
photon and
proton Monte Carlo dose distributions for developing and evaluating advanced dose calculation methods. Acquisition and validation methods: The
dataset comprises paired CT and MRI from 115 patients (75 training, 40 testing) treated on an MRI-linac for thoracic or abdominal lesions, derived from the SynthRAD2025
dataset. Pre-processing included deformable image registration, air-cavity correction, and resampling. Ground-truth
photon (6 MV) and
proton dose distributions were computed using open-source Monte Carlo
algorithms, yielding 40,500
photon beams and 81,000
proton beamlets. Data format and usage notes: Data are organized into
photon and
proton subsets with paired CT-MRI images, beam-level dose distributions, and JSON beam configuration files. Files are provided in compressed MetaImage (.mha) format. The
dataset is released under CC BY-NC 4.0, with training data available from April 2026 and the test set withheld until March 2030. Potential applications: The
dataset supports benchmarking of fast dose calculation methods, including beam-level dose estimation for
photon and
proton therapy, MRI-based dose calculation in MRI-guided workflows, and real-time adaptive radiotherapy.
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All authors Fan Xiao, Nikolaos Delopoulos, Niklas Wahl, Lennart Volz, Lina Bucher, Matteo Maspero, Miguel Palacios, Muheng Li, Samir Schulz, Viktor Rogowski, Ye Zhang, Zoltan Perko, Christopher Kurz, George Dedes, Guillaume Landry, Adrian Thummerer
Classical Physics · Cross-listed from cond-mat.mtrl-sci
Exact demagnetisation field for periodic one-dimensional array of rectangular prisms
Frederik Laust Durhuus, Andrea Roberto Insinga and Rasmus Bjørk
The
magnetic field from a uniformly magnetised, rectangular prism is known exactly, which is the basis for a large number of micromagnetic simulations. Here we derive an analytical solution for the field from a periodically repeating infinite array of prisms aligned end-to-end, which becomes exact on the center axis in the limit of infinitesimally thin prisms. Using the same method we derive the on-axis field for a one-dimensional array of point dipoles. We validate the obtained results numerically and furthermore compare with the common macrogeometry approach and more recent uniform magnetisation method, demonstrating an excellent convergence rate for the novel method.
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Classical Physics · Cross-listed from cond-mat.str-el
Particle Dynamics in Constant Synthetic Non-Abelian Fields
Subramanya Bhat K. N., Amita Das, V Ravishankar et al. (+1 more)
Yang-Mills theory has extended well beyond its original role in describing the strong force and now emerges as an effective theory in condensed matter, ultracold atomic, and photonic systems. In these systems, the theory has been successful in explaining phenomena such as the
spin-
Hall effect,
spin transport, and controlling the polarisation of light. Moreover, the ability to engineer and control synthetic non-Abelian gauge fields in these systems enables us to explore aspects of gauge dynamics inaccessible to high-energy experiments. In all the above mentioned cases, the state of the system evolves in an effective external Yang-Mills field. Thus, the study of test particle dynamics in such background fields is interesting in both the classical and
quantum mechanical regimes. The background non-Abelian (color) gauge fields considered in this study are constant, and they generate uniform color
magnetic fields or combined color electric and
magnetic fields – which are relevant configurations. Despite the apparent simplicity of these backgrounds, the coupled
evolution of real space motion and internal color degrees of freedom results in rich, nontrivial behaviour that is qualitatively distinct from the electrodynamic (Abelian) case, such as unbounded trajectories in a constant color
magnetic field. In particular, particle trajectories encode signatures of the underlying gauge sources. Finally, the classical dynamics presented in this paper serves as a precursor to the complete
quantum mechanical treatment to follow.
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All authors Subramanya Bhat K. N., Amita Das, V Ravishankar, Bhooshan Paradkar
Chemical Physics
Perspective on a challenge: predicting the photochemistry of cyclobutanone
Jiří Janoš, Nanna Holmgaard List, Andrew J. Orr-Ewing et al. (+37 more)
This Perspective is part of a Special Topic that explored the maturity of nonadiabatic molecular dynamics for predicting photochemical processes. In 2023, a prediction challenge was issued to the community of computational photochemists to simulate the photochemistry of cyclobutanone, photoexcited at 200 nm, and the resulting time-resolved MeV-UED signal. The challenge attracted 15 theoretical predictions from more than 70 researchers, employing a wide range of strategies for electronic structure and nonadiabatic molecular dynamics to predict the time-resolved MeV-UED signal before the experiment had been conducted at SLAC (Stanford, USA). The MeV-UED instrument at Shanghai Jiao Tong University was also used to provide a second independent time-resolved MeV-UED signal for the photochemistry of cyclobutanone. This Perspective discusses the various approaches and strategies used by the participants to predict the photochemistry of cyclobutanone. This work also summarizes the strengths and weaknesses of various methods used for photoexcitation, electronic structure, nonadiabatic dynamics, and calculation of observables, as agreed by the participants during a CECAM workshop dedicated to the results of the challenge and organized in Lausanne in April 2025. This Perspective also collects all the predicted time-resolved MeV-UED signals into a single figure, together with the experimental signal. This challenge (i) demonstrated the qualitative predictive power of nonadiabatic molecular dynamics and (ii) underscore the impact of electronic-structure theory on the outcome of the excited-state dynamics and the need for its careful benchmarking. This effort allowed the community to share practical strategies to perform nonadiabatic dynamics (discussed in the present Perspective) and constitutes a 'calibration' exercise for computational photochemistry.
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All authors Jiří Janoš, Nanna Holmgaard List, Andrew J. Orr-Ewing, Jiří Suchan, Mario Barbatti, Olivia Bennett, Marcus Brady, Javier Carmona-García, Rachel Crespo-Otero, Julien Eng, O. Jonathan Fajen, Marco Garavelli, Sandra Gómez, Alice E. Green, Federico J. Hernández, Daniel Hollas, Lewis Hutton, Lea M. Ibele, Adam Kirrander, Zhenggang Lan, Yorick Lassmann, Joseph E. Lawrence, Benjamin G. Levine, Dmitry V. Makhov, Jonathan R. Mannouch, Xincheng Miao, Roland Mitrić, Shane M. Parker, Thomas J. Penfold, Jiawei Peng, Jeremy O. Richardson, Dmitrii Shalashilin, Petr Slavíček, K. Eryn Spinlove, Patricia Vindel-Zandbergen, Federica Agostini, Sara Bonella, Todd J. Martínez, Graham A. Worth, Basile F. E. Curchod
Optics · Cross-listed from quant-ph
Quantum Chaos in Phase Space
Martina Hentschel
Mesoscopic devices, with system sizes in the range of several to several dozens wavelengths, represent paradigmatic model systems for the observation of
quantum chaotic behaviour based on semiclassical concepts. Those electronic and photonic billiard cavities are small enough for interference effects not to be ignored. Nonetheless, the classical ray or particle tracing picture can often provide a substantial understanding of the dynamics of the system along the lines of classical-
quantum, or ray-wave correspondence. This well-established principle turns out to be particularly useful when applied not only in real space, but by extending it to phase space such that both location and momentum information can contribute to a deeper and more comprehensive understanding of the dynamical behaviour.
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Optics · Cross-listed from quant-ph
Decoherence Resilience of the Non-Hermitian Skin Effect
Kunkun Wang, Lei Xiao, Stefano Longhi et al. (+1 more)
Decoherence and dissipation, arising from unavoidable interactions with the environment, can exert a dual influence on transport in physical systems, suppressing coherent propagation while inducing
diffusion and mitigating localization in disordered systems. Non-Hermitian physics reveals a qualitatively different scenario, in which structured dissipation can induce directional bulk-to-boundary transport, known as the non-Hermitian skin effect (NHSE), that remains robust against disorder. Whether such transport can persist, be enhanced or hindered under decoherence, remains a largely open question. Here we experimentally address this question using photonic
quantum walks with two tunable prototypical decoherence channels, dephasing and amplitude damping. Under dephasing, the NHSE survives up to the fully incoherent regime and is observed to even be enhanced by dephasing, yielding drift velocities that exceed those of coherent dynamics. By contrast, amplitude damping shows a pronounced order dependence: applied before the non-Hermitian loss operator, it suppresses and ultimately eliminates the NHSE in the fully incoherent limit; applied afterward, the NHSE persists and can be enhanced at sufficiently large loss strengths. Our work bridges
quantum and classical non-Hermitian dynamics, demonstrates the resilience of the NHSE to decoherence, and opens avenues for harnessing decoherence to enhance directional transport in noisy, nonequilibrium systems.
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All authors Kunkun Wang, Lei Xiao, Stefano Longhi, Peng Xue
Space Physics · Cross-listed from astro-ph.EP
Constraining Electron-Impact Ionization of O$_2$ Through UV Aurora Observations at Ganymede
Stefan Duling, Joachim Saur, Darrell Strobel et al. (+3 more)
While photoionization rates of Ganymede's O$_2$ dominated atmosphere are well constrained, the contribution of electron-impact ionization is rather uncertain. Previous quantitative estimates have relied on assumptions about densities and energy distributions of precipitating electrons, or on rare spacecraft measurements that cannot be unambiguously mapped to the regions of ionization. In this study, we present a novel approach to quantify electron-impact ionization rates directly through OI 1356 Å emission brightness observations. The analysis of measured cross sections reveals that the ionization-to-excitation ratio is limited to 10-60 over all electron energies, reducing the uncertainty of estimating ionization rates to a factor less than 6. We apply this method to Juno UVS observations of Ganymede's aurora. We find that the OI 1356 Å brightness of the auroral ovals is well described by 3-5{\deg} latitude wide Gaussian distributions centered on the open-closed field line boundary, with an average peak of 120 R. The average brightness outside the ovals in the polar and equatorial background regions is ~8 R. From these observations, we derive a global map of electron-impact ionization rates, which are at least an order of magnitude higher than photoionization rates. The estimated total global ionization rate is 1.3-7.6$\times$10$^{26}$ s$^{-1}$, with average column rates of ~5$\times$10$^{9}$ cm$^{-2}$s$^{-1}$ in the ovals and ~3$\times$10$^{8}$ cm$^{-2}$s$^{-1}$ in the background regions. Comparison of
radio occultation measurements with predicted electron densities indicates that transport processes are the dominant loss mechanism in Ganymede's ionosphere. The rate of ionospheric
outflow of O$_2^+$ is 0.1-2$\times$10$^{26}$ s$^{-1}$ or 0.5-11 kg s$^{-1}$, indicating 0.03-0.5 cm Myr$^{-1}$ erosion of Ganymede's surface ice.
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All authors Stefan Duling, Joachim Saur, Darrell Strobel, Philippa Molyneux, Jamey R. Szalay, Thomas K. Greathouse
Optics · Cross-listed from cond-mat.other
Spintronic THz emitters based on NiCu alloys
E. A. Karashtin, I. Yu. Pashen'kin, A. V. Gorbatova et al. (+4 more)
We study THz emission from ferromagnet / nonmagnetic material (FM/NM) spintronic nanostructures in which the $Ni_xCu_{1-x}$
alloy with different $x$ is used as an FM, an NM, or both layers. The stoichiometric composition of the NiCu
alloys standing at two positions (we denote it as [FM] or [PM]) is chosen so that it is
ferromagnetic at room temperature in the case it is used as the FM layer, and is paramagnetic at room temperature for the NM layer. Besides, we choose the nickel ratio $x$ close to each other for both [FM] and [PM] types of the
alloy (the difference is only $10\%$). We show that although NiCu[PM] does not contain heavy metal it acts as an effective converter of
spin current into the electric one in our structure showing only 2.8 times smaller efficiency than Pt. Besides, the NiCu[FM]
alloy, despite having quite small Curie temperature (approximately $65 ^\circ C$), acts as an effective
spin source having the efficiency only 2 times smaller than Co in similar structures. This shows up the importance of boundary matching in the spintronic THz sources. Our NiCu-based THz sources reveal a possibility of effective thermally induced control of emission of THz radiation due to a unique combination of high emission rate and relatively small Curie temperature.
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All authors E. A. Karashtin, I. Yu. Pashen'kin, A. V. Gorbatova, E. D. Lebedeva, P. Yu. Avdeev, N. V. Bezvikonnyi, A. M. Buryakov
Computational Physics · Cross-listed from quant-ph
Ising selector machine by Kerr parametric oscillators
Jacopo Tosca, Cristiano Ciuti, Claudio Conti et al. (+1 more)
Ising machines are physical platforms designed to minimize the energy of classical Ising
Hamiltonians, yet accessing specific excited states remains an open challenge of both fundamental and practical relevance. In this letter we show that a network of Kerr parametric oscillators (KPOs) naturally implements an Ising selector machine. By tuning the frequency detuning between the parametric pump and the oscillator resonances, the system can be steered to converge close to the ground state, the highest-energy configuration, or targeted intermediate excited states. Beyond mean field, numerical simulations based on the truncated Wigner approximation demonstrate that noise insertion preserves the energetic structure of the landscape. The targeted state emerges with an exponentially enhanced probability over the rest of the Ising spectrum. Our results establish the pump-cavity detuning as a control knob for navigating the full Ising energy landscape, opening a route to applications in Boltzmann sampling, hardness characterization, and spectral analysis of combinatorial problems.
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All authors Jacopo Tosca, Cristiano Ciuti, Claudio Conti, Marcello Calvanese Strinati
Applied Physics
Automated Design of Tubular Origami with Anisotropic Stiffness
Mingkai Zhang and Davood Farhadi
Thin sheets can be assembled into tubular origami structures that combine deployability with pronounced anisotropic stiffness, enabling applications ranging from robotics to deployable systems. However, most existing tubular origami designs remain limited to degree-four vertex
topologies and are characterized primarily in axial and radial loading modes, without a full assessment of anisotropic stiffness. Here, we present an automated design framework for tubular origami that jointly explores local vertex
topology through generalized degree-$n$ vertices and global tube
topology through the polygonal cross-section, for the systematic design and optimization of anisotropic stiffness. Using a calibrated bar-and-hinge model together with experimental validation, we quantify large-deformation stiffness responses in axial translation, in-plane translation, torsion about the tube axis, and rotation about in-plane axes, thereby characterizing the anisotropic stiffness of the tube across its compliant and constrained deformation modes. The resulting design-space exploration showed that the polygonal cross-sectional
topology is the primary factor governing the anisotropic stiffness. We further show that increasing the local vertex degree can improve global structural performance, particularly for tubes with a small number of cross-sectional vertices, demonstrating that higher local kinematic freedom does not necessarily compromise stiffness at the structural scale. Compared with a
benchmark design, the optimized architectures achieve more than 50 times higher constrained rotational stiffness. Together, these results highlight higher-degree vertices and polygonal cross-sectional
topology as powerful design variables for tailoring anisotropic stiffness in tubular origami.
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Chemical Physics
Transferable excited-state dynamics enable screening of fluorescent protein chromophores
Rhyan Barrett, Sophia Wesely and Julia Westermayr
Transferable excited-state dynamics offer a route to efficient screening of photophysical behavior across molecular systems, but conventional nonadiabatic simulations remain prohibitively expensive. Here we introduce X-MACE, a transferable machine-learning potential for excited-state dynamics that predicts multiple potential energy surfaces, forces and oscillator strengths, and combine it with
curvature-driven surface hopping to enable data-efficient screening of photochemical pathways. We apply this framework to fluorescent chromophores as an example application, using green fluorescent
protein chromophore variants to demonstrate how subtle structural modifications reshape excited-state relaxation, lifetimes and photoisomerization yields. Fine-tuning a single pretrained model with fewer than 100 reference geometries per derivative yields accurate dynamics across a chemically diverse set of analogues. The screening reveals two governing design principles: steric crowding on the phenolate ring lowers the torsional barrier and accelerates access to twisted conical intersections, whereas conjugation extension stabilizes planar excited-state configurations, suppresses non-radiative decay and prolongs fluorescence. More broadly, this workflow provides a general framework for scalable excited-state screening and interpretable design of photophysical properties.
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Physics and Society
Signed DeGroot-Friedkin Dynamics with Interdependent Topics
Yangyang Luan, Muhammad Ahsan Razaq, Xiaoqun Wu et al. (+1 more)
This paper investigates DeGroot-Friedkin (DF) dynamics over signed influence networks with interdependent topics. We propose a multi-topic signed framework that combines repelling interpersonal interactions with cross-issue self-appraisal, examining how antagonism and topic interdependence shape the
evolution of
agent-level social power. When the logic
matrices (for topic interdependence) of all
agents share a common dominant left eigenvector, we identify structural conditions under which the original dynamics admit an exact reduction to an explicit scalar DF map. This yields a complete classification of limiting social power configurations into pluralistic, mixed, and vertex-dominant types. In all three cases, the dynamics are globally convergent, and in the first two the ordering induced by the interaction centrality is preserved. We further show local robustness under small heterogeneous perturbations of the logic
matrices. We also clarify what changes when this common-eigenvector structure is lost. These results extend signed social power dynamics beyond the standard nonnegative scalar setting and shed light on the robustness and scope of centrality-based social power formation in multi-topic signed influence systems.
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All authors Yangyang Luan, Muhammad Ahsan Razaq, Xiaoqun Wu, Claudio Altafini
Applied Physics
Position-Dependent Calibration and Frequency Stability in On-Axis Optical Transduction of Vertical InP Nanowire Resonators
Robert G. West, Kostas Kanellopulos, Lukas Hrachowina et al. (+2 more)
We present a quantitative framework for on-axis optical transduction of vertical InP nanowire resonators, correlating
laser position to signal amplitude, calibration, and frequency stability. Photothermal resonance detuning is used to reconstruct the local beam intensity profile and to calibrate the photodetector signal using the thermomechanical noise. A noise model incorporating shot noise and spatial variation in substrate reflectance predicts the position-dependent Allan deviation. We find that the optimal detection position lies near the steepest intensity gradient, and that increasing
laser power does not significantly improve frequency stability, because the accompanying temperature rise enhances thermomechanical noise and offsets the signal gain. These results establish design guidelines for optimizing nanowire-based sensors in on-axis optical detection schemes.
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All authors Robert G. West, Kostas Kanellopulos, Lukas Hrachowina, Magnus Borgström, Silvan Schmid
Fluid Dynamics
Bayesian-Enhanced Galerkin-Based Reduced Order Modelling for Unsteady Compressible Flows
Bijie Yang, Chengyuan Liu, Lu Tian et al. (+2 more)
This work proposes a statistically enhanced framework to address the instability and limited predictive capability of conventional Galerkin-Proper Orthogonal Decomposition (Galerkin-POD) models. The method reformulates the correction of the Galerkin-projected ODE system as a statistical inverse problem, in which the coefficients are inferred through
Bayesian inference. By accounting for model uncertainty arising from POD mode truncation and data uncertainty introduced by data noise and numerical postprocessing, the framework systematically updates the ODE system coefficients using an analytical, sampling-free solution based on Gaussian likelihood and inverse-Gamma priors. The approach is first validated using a self-sustained oscillating flow over a dimpled surface at a moderate Reynolds number (Re=3000), demonstrating stable and accurate reproduction of the temporal dynamics and phase trajectories of coherent structures when compared with direct numerical simulation (DNS). It is then applied to a centrifugal compressor featuring strong tip-leakage
vortex breakdown and impeller-diffuser interactions at Re=100000, where the model successfully captures dominant unsteady structures and frequency characteristics despite limited mode retention. Overall, the results show that
Bayesian inference substantially enhances the robustness, stability, and predictive fidelity of Galerkin-POD models for compressible flow systems. The proposed methodology combines the physical interpretability of Galerkin projection with the statistical rigour of
Bayesian inference, offering a general, computationally efficient, and uncertainty-aware reduced-order modelling framework for complex fluid dynamic applications.
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All authors Bijie Yang, Chengyuan Liu, Lu Tian, Yuping Qian, Mingyang Yang
Atomic Physics · Cross-listed from quant-ph
Interferometrically Enhanced Asymmetry in Strong-field Ionization with Bright Squeezed Vacuum
G. Singh, T. Rook, J. Rivera-Dean et al. (+1 more)
We demonstrate that
quantum light statistics can be used to control strong-field ionization at the tunneling step. Using a bichromatic linearly polarized field composed of a strong coherent driver and a weak bright squeezed
vacuum (BSV), we show through simulation that photoelectron momentum distributions (PMDs) exhibit asymmetries that exceed those obtained with classical fields of comparable intensity by orders of magnitude. This enhancement is uniquely linked to the nonclassical statistics of the BSV field. A semiclassical analysis based on the strong-field approximation (SFA) reveals that the effect originates from fluctuations in the instantaneous field amplitude, which strongly modify the tunneling ionization probability while leaving the electron's continuum dynamics essentially unchanged. This selective control enables reconstruction of ionization pathways and provides a robust route to extract sub-cycle dynamics from strong-field observables.
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All authors G. Singh, T. Rook, J. Rivera-Dean, C. Figueira de Morisson Faria
Optics
Voltage-Programmable Photon Statistics Using a High-Extinction Thin-film Lithium Niobate Modulator
Julian Rasmus Bankwitz, Ravi Pradip, Julius Römer et al. (+9 more)
Controlling the statistical properties of light, namely the fluctuations in
photon arrival,
entropy and number, is essential for both classical and
quantum photonics. While integrated systems provide tunable control over amplitude, phase, and wavelength, real-time modulation of
photon statistics has remained a long-standing challenge. Herein, we introduce the concept and experimental realization of a
photon statistics transducer: a high-extinction, broadband electro-optic device capable of deterministically shaping
photon-number distributions at nanosecond timescales. Our approach employs a cascaded thin-film lithium niobate (TFLN) Mach-Zehnder amplitude modulator delivering more than 50 dB extinction, enabling precise suppression and release of coherent seed light from an integrated InP
laser. By exploiting the interplay between seed suppression and erbium-doped fiber amplifier dynamics, we demonstrate smooth, voltage-controlled switching between Poissonian and super-Poissonian
photon statistics, with second-order coherence g2(0) tunable from 1.0 to 1.7. Complementary measurements with superconducting nanowire single-
photon detectors further show
photon-flux control down to sub-
photon levels, highlighting the potential for future operation with non-classical sources. The
photon statistics transducer thus establishes statistical modulation as a new functional primitive in integrated photonics. Applications range from
entropy generation and secure communication to neuromorphic and hybrid
quantum-classical processing, where controlled randomness and
entropy are essential resources. By enabling programmable transitions between statistical regimes using only electronic drive signals, our work lays the foundation for adaptive,
entropy-aware photonic systems that bridge classical and
quantum domains.
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All authors Julian Rasmus Bankwitz, Ravi Pradip, Julius Römer, Frank Brückerhoff-Plückelmann, Falk Ebert, Lennart Meyer, Liam McRae, Jan Brandes, Akhil Varri, Wladick Hartmann, Wolfram Pernice, Xinyu Ma
Chemical Physics
Exact tunneling splittings from path-integral hybrid Monte Carlo with enveloping bridging potentials
Yu-Chen Wang and Jeremy O. Richardson
A path-integral hybrid Monte Carlo approach with enveloping bridging potentials (PIHMC-EBP) is proposed for calculating numerically exact tunneling splittings in molecular systems. The central idea is to construct an approximately barrierless bridging potential that smoothly connects
symmetry-related regions of ring-
polymer phase space, enabling direct sampling of the free-energy profile from which the relevant splittings are obtained. Two tailored nonlocal updates are designed to enhance the sampling of slow collective motions. Compared with path-integral molecular dynamics using thermodynamic integration, PIHMC-EBP requires neither quadrature nor time-step convergence checks, thereby substantially reducing the manual effort required to analyze the results. Applications to malonaldehyde (and its deuterated isotopologue) and the HCl dimer using state-of-the-art potential energy surfaces provide the most precise tunneling splittings reported to date for both systems, while simultaneously reducing the overall computational cost by several times and three orders of magnitude, respectively. Finally, application to the water dimer yields the first numerically exact path-integral calculations of the ground-state tunneling splittings on three different potential energy surfaces, all obtained simultaneously by reweighting a single set of trajectories.
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Chemical Physics
Exact tunneling splittings of rotationally excited states from symmetrized path-integral molecular dynamics
Lea Zupan, Yu-Chen Wang and Jeremy O. Richardson
We extend our previous symmetrized path-integral molecular dynamics approach to calculate tunneling splittings of molecules in rotationally excited states. In this new formalism, the system is rigorously projected onto selected rotational
manifolds and states of a chosen
symmetry through an Eckart spring, which connects the two end beads of the ring
polymer via a permutation–inversion–rotation operation. This method is numerically exact within statistical uncertainty once convergence with respect to all simulation parameters has been achieved. Importantly, it enables the simultaneous extraction of tunneling splittings for multiple total angular-momentum
quantum numbers $J$ from a single set of simulations, without additional computational cost relative to the original approach. After validating the formalism by computing the rotational levels of water (beyond the rigid-rotor approximation), we apply it to ammonia and obtain rotationally resolved tunneling splittings in excellent agreement with exact variational
benchmarks. Except for small errors due to the underlying potential energy surface, the results capture the experimentally observed trend that the tunneling splitting decreases with $J$.
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Applied Physics · Cross-listed from cond-mat.mtrl-sci
Nonmonotonic Scaling of the Anomalous Hall Effect in a Bicollinear Antiferromagnet
Ruifeng Wang, Chi Fang, Ilya Kostanovski et al. (+5 more)
An anomalous
Hall effect (AHE) in
antiferromagnetic (AF) systems with no net magnetization is of considerable interest for both fundamental physics and spintronic applications. Of particular interest is the two-dimensional van der Waals antiferromagnet FeTe that has an unusual fully magnetically compensated bicollinear AF structure and exhibits pronounced Kondo interaction leading to strong band renormalization. Here, we investigate the AHE in epitaxial FeTe thin films grown by molecular beam epitaxy. A large anomalous
Hall conductivity is exhibited below the Neel temperature (T_N ~ 60 K) and, strikingly, becomes nonlinear at high fields within a narrow temperature window around 49 K, deviating from conventional AHE scaling behavior versus its longitudinal conductivity. Linear fits reveal a pronounced negative peak in the intercept, accompanied by a field-induced canted
magnetic moment. The AHE responses are related to the Berry
curvature derived from FeTe's topological band structure, highlighting the intricate interplay between
topology, magnetism, and electronic transport.
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All authors Ruifeng Wang, Chi Fang, Ilya Kostanovski, Ke Xiao, Felix Küster, Jenny Davern, Naoto Nagaosa, Stuart S. P. Parkin
Computational Physics
Hierarchical generative modeling for the design of multi-component systems
Rhyan Barrett, Robin Curth and Julia Westermayr
The functionality of catalysts, enzymes, and supramolecular assemblies emerges not from individual molecules alone, but from the subtle interplay between multiple components arranged in complex systems. Designing such systems is a grand challenge, the combinatorial explosion of possible chemical compositions and spatial arrangements makes brute-force exploration infeasible, while many current generative approaches remain limited to isolated molecules. In this work, we introduce a hierarchical generative optimization framework that overcomes this barrier by coupling a genetic
algorithm for configurational search with a generative model for molecular design. This closed-loop approach enables simultaneous refinement of geometry and composition, efficiently steering discovery toward systems with targeted functionality. As a proof of concept, we design catalytic environments for the Claisen rearrangement of p-tolyl ether by optimizing surrounding components around a fixed reference transition-state geometry. Despite this constraint during the search phase, post-hoc validation via Climbing-Image Nudged Elastic Band calculations confirm a 30% reduction in activation barrier. Beyond this example, our framework provides a general strategy for data-driven discovery of functional multi-component systems, opening the door to automated design of catalysts, enzyme active sites, and advanced materials. Scientific contribution. The study presents a closed loop generative framework that enables joint optimization of molecular components and their spatial organization in multi-component systems. The method moves generative molecular design beyond single molecules toward larger and more complex systems.
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Optics · Cross-listed from cond-mat.mes-hall
Correlation functions for quantum dynamics of coupled quasinormal modes and quantum emitters interacting via finite-delay propagating photons
Robert Meiners Fuchs, Juanjuan Ren, Sebastian Franke et al. (+2 more)
A time-dependent theory for the interactions between spatially separated lossy cavities in a homogeneous background medium using quantized quasinormal modes (QNMs) is presented. The cavities interact via a bath of traveling
photons, described by non-bosonic operators that are orthogonal to the open-cavity QNMs. The retarded (i.e., time-delayed) inter-cavity dynamics are fully described by system-bath correlation functions, in which the emission from one cavity appears as the input field for another. Coupling between
quantum emitters (described as two-level systems), placed inside a cavity or embedded in an external medium, and the electromagnetic field (cavity modes and bath
photons) is included in the theory, which gives rise to both bath-mediated and QNM-mediated interactions between the emitters.
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All authors Robert Meiners Fuchs, Juanjuan Ren, Sebastian Franke, Stephen Hughes, Marten Richter
Optics
Open dataset for benchmarking scaling laws of high-energy laser atmospheric propagation
Xusheng Xia and Zhilin Xia
Scaling laws are increasingly used as fast surrogate models for high energy
laser atmospheric propagation, yet their calibration and comparison still depend on large collections of high-fidelity wave-optics simulations. Existing studies usually rely on privately organized simulation outputs, which makes it difficult to reproduce published fits or evaluate new surrogate formulations on a shared
benchmark. We present a public simulation
dataset for high energy
laser atmospheric propagation with coupled
turbulence and thermal blooming. The release contains 226,500 cases spanning target speed, emission geometry, aperture diameter, visibility, aerosol model, beam quality,
turbulence strength, and
laser power. Data are organized as a case-level main table linked to indexed long-exposure irradiance arrays and centralized metadata, which supports statistical analysis without hiding the underlying field outputs. The simulation pipeline is based on split-step wave-optics propagation with
turbulence, attenuation, and thermal-blooming models that have been validated against established propagation references. The
dataset is intended for scaling-law calibration,
benchmark comparison, surrogate-model training, sensitivity analysis, and inverse studies.
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Optics
High intensity attosecond beamline for XUV pump XUV probe measurements with photon energies up to 150 eV
Sajjad Vardast, Alexander Muschet, N. Smijesh et al. (+9 more)
The field of attosecond physics has expanded significantly in recent years, yet experimental facilities supporting attosecond pump attosecond probe spectroscopy remain rare. Here, we present a newly constructed beamline for the generation and application of energetic, isolated extreme ultraviolet (XUV) and soft X-ray attosecond pulses via upscaling of high-harmonic generation (HHG) in a gas medium. The fundamental properties of the HHG radiation energy, beam profile, spectrum, and divergence are characterized and optimized. The source delivers up to 55 nJ of pulse energy within the Zr window (65-150 eV) with high stability (~5-10) and a divergence of 0.1 mrad. Numerical simulations identify optimal operating conditions consistent with experimental results. Temporal super-resolution of the driving
laser is applied, resulting in a broadened spectral continuum. Furthermore, the beamline includes a split-and-delay stage before focusing the HHG radiation to a <6 um spot for pump-probe experiments using two distinct focusing optics. Spatially resolved ion microscopy is employed to trace the generated ions at the focus. The presented beamline is designed for nonlinear XUV studies with attosecond isolated pulses.
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All authors Sajjad Vardast, Alexander Muschet, N. Smijesh, Mohammad Rezaei-Pandari, Fritz Schnur, Robin Weissenbilder, Elisa Appi, Jan Lahl, Sylvain Maclot, Per Eng-Johnsson, Anne L'Huillier, Laszlo Veisz