Papers

Fresh from arXiv, typeset properly. Highlighted words trade on the market.

Physics

Wednesday 17 June

Strongly Correlated Electrons

Hallmark Signatures of Electronic Pairing in Two-Photon Two-Electron Coincidence Angle-Resolved Photoemission Spectroscopy

Janez Bonca, Alberto Nocera, Andrea Damascelli et al. (+1 more)

Understanding strongly correlated quantum materials remains a central challenge in condensed matter physics and materials science. While angle-resolved photoemission spectroscopy (ARPES) has become an indispensable probe of single-quasiparticle excitations, it accesses electronic correlations only indirectly. Here we show that unlike one-photon in, two-electrons out coincidence ARPES ($\gamma\!\rightarrow\!2e$ 2eARPES), the two-photon in, two-electron out $2\gamma\!\rightarrow\!2e$ 2eARPES provides a direct and unambiguous probe of electronic pairing. We establish this on general theoretical grounds and substantiate it through large-scale numerical simulations of strongly correlated models with both paired and unpaired ground states. The key result is a model-independent separation in the $(\omega_1,\omega_2)$ plane of the two photoelectrons' energies, between signal from electrons emitted from the same pair and signal from electrons emitted from different pairs; this follows from energy conservation alone and is independent of any material-specific assumptions. Our findings demonstrate that $2\gamma\!\rightarrow\!2e$ 2eARPES can identify pairing and extract the pair binding energy as well as the energy of the 'glue' boson without any sophisticated data analysis or complementary measurements.

Read the full abstract

All authors Janez Bonca, Alberto Nocera, Andrea Damascelli, Mona Berciu

Instrumentation and Detectors

A Search for Effects of Cosmic Rays with Multi-scale Entropy Metrics

William M. Campbell, Ben T. McAllister, Eugene N. Ivanov et al. (+4 more)

We report a comparison of frequency fluctuations in oven-controlled quartz bulk-acoustic-wave oscillators operated above ground and one kilometre underground in a low-muon-background environment. The experiment is motivated by the possibility that cosmic rays and other ionizing-radiation backgrounds produce rare, impulsive energy-deposition events that perturb high-Q mechanical resonators and appear as intermittent, non-Gaussian structure in oscillator frequency noise. Conventional power spectral density and Allan-deviation analyses show no statistically compelling separation between the two environments over the explored timescales. In contrast, multi-scale sample entropy and its modified form reveal a pronounced divergence, with the underground data exhibiting increased predictability over a broad range of effective integration times. This result identifies a change in the temporal structure of the oscillator fluctuations that is largely hidden from standard second-order frequency-stability metrics. We therefore propose multi-scale sample entropy as a new diagnostic for frequency control and timing, complementary to Allan deviation and spectral analysis, with particular sensitivity to intermittent structure, non-stationary contributions, and rare-event contamination. The observed entropy separation also provides evidence that the above-ground cosmic-ray environment influences oscillator frequency fluctuations, suggesting that radiation-linked disturbances may contribute to the stochastic behaviour of precision mechanical oscillators. These findings introduce an entropy-based methodology for oscillator metrology and provide a practical tool for future fundamental-physics experiments using cryogenic resonant sensors, where rare-event backgrounds and poorly understood low-frequency noise can limit sensitivity.

Read the full abstract

All authors William M. Campbell, Ben T. McAllister, Eugene N. Ivanov, Michael E. Tobar, Mehran Mossammaparast, Mike Sawicki, Maxim Goryachev

Quantum Physics

Characterization of three-qubit controlled unitary gates of Schmidt rank three

Xiutao Zhang

We characterize three-qubit controlled unitary gates of Schmidt rank three, establishing necessary and sufficient conditions for such gates to have Schmidt rank three. We construct explicit examples and analyze their entanglement capabilities, showing that gates with Schmidt rank three can generate output states ranging from fully separable to maximal GHZ-class states. Within this classification, we present a parameterized gate family that produces an output W-class state whose bipartite tangles for subsystems AB and AC are modulated as simple trigonometric functions of a single phase parameter. The examples also include gates implementable with only three CNOT gates, showing that this lower bound is achievable. Decompositions that achieve the minimum possible CNOT count for several other cases are provided as well. Our results bridge Schmidt rank classification, entanglement structure, and resource-efficient circuit synthesis.

Read the full abstract

High Energy Astrophysical Phenomena

A Log-Uniform Initial Magnetic Field Distribution Explains Pulsar and Magnetar Populations through Magnetic Inclination Alignment

Takumi Shimasue, Kenta Hotokezaka and Paz Beniamini

The origin of the gap in the observed magnetic field distribution between pulsars and magnetars raises a challenge to understanding these populations within a unified framework. We analytically show that the gap can be naturally explained by the alignment of the magnetic inclination angle between the magnetic and spin axes. Based on coupled evolution of spin-down and magnetic inclination angle in the plasma-filled magnetosphere, the alignment timescale follows $\tau_\alpha \propto B^{-2}$. Thus, strongly magnetized neutron stars including high-$B$ pulsars and magnetars align more rapidly than pulsars with $10^{12}\,\mathrm{G}$, reducing their beaming fraction and thereby suppressing their observed numbers. However, magnetars are primarily identified through X-ray activity and are therefore relatively less affected by beaming. Taking into account both beaming fraction and luminosity corrections, we reconstruct the initial magnetic field distribution from the observed distribution. We show that pulsars and magnetars do not dictate intrinsically distinct initial distributions, but can instead be understood within a single continuous initial magnetic field distribution, such as a log-uniform distribution.

Read the full abstract

Quantum Physics

The quantum-advantage resource in multimode OPA light: Identification, optimization, extraction

Vitaly Kocharovsky and Kunwar Kalra

We introduce the notion and reveal remarkable properties of quantum complexity resource contained in a mixed multimode Gaussian state and providing universal quantitative characterization of its quantum advantage. The notion is based on convex optimization, multimode photon number statistics, Hafnian Master Theorem, and #P-hard complexity. We consider pulsed OPAs targeting maximal quantum complexity resource and thousands of multipartite-entangled squeezed modes of output light via nonlinear, spatio-temporally nonadiabatic generation inside OPA and optimized extraction out of OPA. We show that such figure of merit is more realistic than Bloch–Messiah supermodes and guides to multimode OPAs opening new paths to important applications in quantum information science such as generation of 3D cluster states for one-way photonic quantum computing and demonstration of quantum advantage.

Read the full abstract

Biological Physics

A symmetric relaxation method for entire two-dimensional cellular networks and its implications

Kai Xu, Lifan Weng, Zihan Wang et al. (+2 more)

To simulate the relaxation of an entire 2D cellular network, this study proposes a symmetric relaxation method for both inner and marginal vertices. The relaxations of these two types of vertices are determined by the central angle symmetry of associated cells and the angle symmetry at each vertex, but with different major considerations. Trimmed Voronoi networks with varying irregularity are used as initial networks for the relaxation simulation. In particular, we propose a regular hexagon disordering method to generate Voronoi networks and find that the inner cells of networks with an irregularity value of one exhibit a conserved edge number distribution, as found in other 2D cellular networks. Simulation results agree with the von Neumann-Mullins law for both inner and marginal cells, and a modified equation including a geometric correction term significantly improves prediction quality. The Aboav-Weaire law and Lewis law are also reproduced, with the latter showing that relaxed cells tend to approach the ellipses' maximum inscribed polygons. Analysis of edge length, interior angle, and shape index reveals that symmetric relaxation inhibits T1 (neighbour exchange) topological transitions by reducing short edges while increasing area disparity among neighbouring cells. The findings suggest that T1 events may be triggered when force disequilibrium overcomes the stabilising effect of symmetric relaxation, providing a possible mechanistic explanation for T1 in 2D foams.

Read the full abstract

All authors Kai Xu, Lifan Weng, Zihan Wang, Yuyang Lian, Bin Huang

Materials Science

Strain induced magnetic phase transition and anomalous transport phenomena in RuO$_2$ and MnF$_2$

Xiuxian Yang, Zhangqi Wu, Xiangju Wang et al. (+6 more)

Collinear antiferromagnets with broken time-reversal symmetry have emerged as a fertile platform for spintronics. Using a general tight-binding model and first-principles calculations, we show that strain engineering provides a simple route to control magnetic phase transition and activate transverse responses in representative altermagnets RuO$_2$ and MnF$_2$. For pristine RuO$_2$ and MnF$_2$ with Néel vector $\mathbf{n}\parallel$ [001], symmetry constrains the off-diagonal elements of the Hall conductivity tensor to vanish, thereby forbidding anomalous transport and magneto-optical responses. Shear strain applied along the $ac$ direction preserves the spin symmetry relating the two spin-opposite magnetic sublattices and therefore maintains the altermagnetic phase. By contrast, shear strain applied along the $ab$ direction breaks this spin symmetry and drives a transition from an altermagnetic phase to a partially compensated ferrimagnetic phase in metallic RuO$_2$ and to a fully compensated ferrimagnetic phase in semiconducting MnF$_2$. In addition, the lowered symmetry enables finite anomalous Hall, anomalous Nernst, and anomalous thermal Hall conductivities, as well as magneto-optical rotation angles, which are prohibited in the pristine systems. These responses exhibit a clear strain dependence and become progressively stronger as the strain amplitude increases. Our results establish strain engineering as an effective route to manipulate magnetic phases and functional responses in unconventional antiferromagnets, thereby expanding opportunities for antiferromagnetic spintronics and magneto-optical applications.

Read the full abstract

All authors Xiuxian Yang, Zhangqi Wu, Xiangju Wang, Shifeng Qian, Ping Yang, Xiaodong Zhou, Jian Hao, Wanxiang Feng, Yinwei Li

Fluid Dynamics

Response of a Turbulent Boundary Layer to a Synthetic Periodic Large-Scale Structure

Mitchell Lozier, Flint O. Thomas and Stanislav Gordeyev

The dynamic response of a zero-pressure gradient turbulent boundary layer (TBL) to a large-scale perturbation in the outer region was investigated experimentally. The baseline TBL had a moderate Reynolds number such that there was no naturally occurring energetic large-scale structure (LSS) present. An active plasma-based actuator was then placed in the outer region of the TBL to introduce a periodic, spanwise-uniform, synthetic LSS. This novel actuation scheme provides a new tool by which to experimentally examine the `top-down' view of TBL dynamics/interactions. The TBL response to this synthetic structure was investigated using a combination of planar particle imaging velocimetry and spanwise offset hot-wires, over a large streamwise extent downstream of the actuator device. Phase-locked analysis was implemented to isolate and measure the streamwise development of large-scale motions and changes in turbulence amplitude induced by this synthetic LSS. A strong correlation was observed between large-scale motions near the wall, linearly superimposed from the synthetic LSS, and a periodic modulation of turbulence amplitudes. This periodic modulation was found to be linked to phase-dependent changes in both the production and transport of turbulence driven by the induced large-scale motions. The phase speed of these induced large-scale motions, coupled with intermittent changes to spanwise coherence near the wall, revealed an additional, but transient, effect of the synthetic LSS on near-wall cycle dynamics. Overall, these results characterize the influences, and limitations, of top-down interactions on global TBL dynamics.

Read the full abstract

High Energy Physics (Phenomenology)

Analysis of $J/\psi$ and $\psi(2S)$ Charmonium Production in Ultraperipheral Lead-Lead and Proton-Lead Collisions at LHC Energies

Zhe Wang, Jiyuan Zhang and Xiao-Yun Wang

The two gluon exchange model serves as a key framework for describing the photoproduction of heavy vector mesons, and the photoproduction cross sections derived from it provide essential input for studies of Ultra-Peripheral Collisions (UPCs). Building on the model successful description of $J/\psi$ and $\psi(2S)$ photoproduction in previous work, we use the STARlight program to systematically investigate charmonium UPCs in PbPb and $p$Pb collisions at LHC energies. To reduce discrepancies between theoretical predictions and experimental data for rapidity and transverse momentum distributions in PbPb collisions, a phenomenological suppression factor is introduced to correct the theoretical results. We find that, in the TeV energy range, the corrected predictions agree well with experimental data within uncertainties and successfully reproduce the characteristic double-peak structure in rapidity distributions. In contrast, no significant suppression is observed in $p$Pb UPCs, which reflects the asymmetric photon fluxes and the dominant contribution from the photoproduction interaction branch. The transverse momentum distributions from STARlight simulations also match the diffractive pattern of coherent production seen experimentally, although the overall yield remains slightly overpredicted. This work further validates the applicability of photoproduction cross sections from the two gluon exchange model for charmonium UPC studies, and offers valuable phenomenological guidance for future experimental design and data analysis in UPC measurements of charmonium production.

Read the full abstract

High Energy Astrophysical Phenomena

SN 2024dy: Dust formation in a long-lived Type IIn supernova and constraints on the dust mass

Sota Goto, Masayuki Yamanaka, Koji S. Kawabata et al. (+10 more)

Type~IIn supernovae (SNe) are a subclass of core-collapse SNe powered by interaction between the ejecta and the dense circumstellar material. Among them, long-lived Type~IIn events are characterized by luminous, long-duration light curves with high radiative energy. Several cases of long-lived type IIn SNe exhibit substantial dust emission at late times. However, well-observed examples remain limited, and the details of their dust formation mechanisms remain poorly understood. Here we present photometric and spectroscopic observations of the Type~IIn SN~2024dy in ultraviolet, optical, and near-infrared (NIR) wavelength for $500$ days. SN~2024dy reached a peak magnitude of $M_r=-19.2$~mag with a total radiation energy of $1.9\times10^{50}$~erg. A NIR excess emerged at late phases, and the spectral energy distribution modeling indicates the presence of carbon dust with temperatures of $1300$-$1800$~K and masses of about $10^{-5}\ M_\odot$. The spectra features were typical of long-lived Type~IIn SNe. The late time H$\alpha$ profile exhibits a strong suppression of the red wing, providing evidence for newly formed dust. Our results suggest that the derived dust mass above may be underestimated due to optical depth effects. SN~2024dy provides an important observational case for understanding dust formation in Type~IIn SNe.

Read the full abstract

All authors Sota Goto, Masayuki Yamanaka, Koji S. Kawabata, Masaomi Tanaka, Avinash Singh, Devendra K. Sahu, Tatsuya Nakaoka, Anjasha Gangopadhyay, Takahiro Nagayama, Naveen Dukiya, Monalisa Dubey, Kuntal Misra, Bhavya Ailawadhi

Cosmology and Nongalactic Astrophysics

DESI Data Release 2 ELGs: Property-dependent subsamples, imaging systematics, and clustering

T. Hagen, K. S. Dawson, Z. Zheng et al. (+42 more)

Using emission-line galaxies (ELGs) from the Dark Energy Spectroscopic Instrument (DESI) Data Release 2, we evaluate a property-dependent correction to imaging systematics. We derive systematic weights following the same linear regression method used for other DESI tracers, but do so separately on ELG subsamples to provide a physically-informed alternative to the fiducial, neural-network-based approach. In doing so, we show that the deeper imaging in the Dark Energy Survey (DES) footprint leads to a higher overall number density but a lack of targets with extreme $g-r$ and $r-z$ colors. ELGs in the DES region also show a distinct redshift distribution when subsampled by position in the $g-r$ vs. $r-z$ plane. To address these effects, we implement a separate treatment of the DES footprint within the DESI catalog production pipeline, which is generally well-motivated and, in some cases, imperative for accurate clustering measurements. With DES treated separately, we find that property-dependent systematic weights further mitigate spurious clustering signal in $\sim$10% of subsamples, while the fiducial scheme remains optimal for the full sample.

Read the full abstract

All authors T. Hagen, K. S. Dawson, Z. Zheng, J. Aguilar, S. Ahlen, D. Bianchi, D. Brooks, T. Claybaugh, A. de la Macorra, B. Dey, S. Ferraro, J. E. Forero-Romero, S. Gontcho A Gontcho, G. Gutierrez, J. Guy, C. Hahn, M. Ishak, R. Joyce, S. Juneau, A. Kremin, O. Lahav, C. Lamman, M. Landriau, L. Le Guillou, M. Manera, A. Meisner, R. Miquel, J. Moustakas, A. D. Myers, S. Nadathur, J. A. Newman, G. Niz, W. J. Percival, C. Poppett, F. Prada, I. Perez-Rafols, A. J. Ross, G. Rossi, S. Saito, E. Sanchez, D. Schlegel, J. Silber, G. Tarle, B. A. Weaver, H. Zou

Quantum Physics

Separation of Statistical Complexity and Trainability in Variational Quantum Circuits

Suman Mandal, Maximillian Daughtry and Eduardo R. Mucciolo

Variational quantum algorithms (VQAs) are among the leading approaches for near-term quantum computing, yet their performance can degrade in barren plateau regimes characterized by vanishing gradients. A widely held intuition is that increasing circuit expressivity, often associated with random-state behavior, leads to a loss of trainability. Existing results show that sufficiently random circuits can lead to barren plateaus. Here we show that standard statistical signatures of randomness can emerge well before this regime, without degrading trainability. We demonstrate this behavior in structured variational circuits applied to the one-dimensional cluster-Ising model and a generalized toric code Hamiltonian. To characterize state complexity, we analyze Porter-Thomas statistics, entanglement-spectrum level statistics, and inverse participation ratios. Across both models, increasing circuit depth drives these diagnostics toward random-state-like or random-matrix-like behavior, while variational optimization remains effective, with no evidence of exponential gradient suppression in the regime studied. We interpret this behavior in terms of locality. Spectral correlations develop at relatively shallow depth through locally generated structure, while global state randomization and the associated concentration-of-measure effects are not yet realized. These results show that commonly used statistical diagnostics of complexity do not by themselves determine trainability. Instead, they point to a separation between different aspects of complexity in finite-depth variational circuits.

Read the full abstract

High Energy Physics (Phenomenology)

Semi-leptonic decays $B \to D^{(*)}(1S,2S)\ell \nu_{\ell}$ within the covariant light-front approach

Zhi-Jie Sun, Zhi-Qing Zhang, Shi-Chen Xue et al. (+1 more)

We present a systematic analysis of the semi-leptonic decays $B_{(s)}\to D_{(s)}(1S,2S)\ell\nu_\ell$ and $B_{(s)}\to D^*_{(s)}(1S,2S)\ell\nu_\ell$ with $\ell=e,\mu,\tau$ within the covariant light-front quark model (CLFQM). Using the form factors of the transitions $B_{(s)}\to D_{(s)}(1S,2S)$ and $B_{(s)}\to D^*_{(s)}(1S,2S)$, we calculate the branching ratios of the relevant semi-leptonic decays and find that $Br(B_{(s)}\to D_{(s)}\ell^\prime\nu_{\ell^\prime})$ and $Br(B_{(s)}\to D^*_{(s)}\ell^\prime\nu_{\ell^\prime})$ with $\ell^\prime=e,\mu$ are agree well with the data, while $Br(B_{(s)}\to D_{(s)}\tau\nu_{\tau})$ and $Br(B_{(s)}\to D^*_{(s)}\tau\nu_{\tau})$ are systematically smaller than the experimental measurements. This naturally gives rise to the so-called $\mathcal{R}(D)$ and $\mathcal{R}(D^*)$ anomalies. Our predictions $\mathcal{R}(D)=0.261\pm0.013$ and $\mathcal{R}(D^*)=0.228\pm0.026$ show $3.1\sigma$ and $2.1\sigma$ deviations from the current experimental world averages compiled by the Heavy Flavor Averaging Group (HFLAV), respectively, yet only deviate by $0.16\sigma$ and $1.5\sigma$ from the latest LHCb measurements. For the decays $B_{(s)}\to D_{(s)}(2S)\ell\nu_\ell$ and $B_{(s)}\to D^*_{(s)}(2S)\ell\nu_\ell$, their branching ratios lie in the range $10^{-4}\sim10^{-3}$, which are much larger than the results from the Bethe Salpeter (BS) equation , but agree with the relativistic quark model (RQM) calculations. Furthermore, we also calculate the forward-backward asymmetries $\mathcal{A}_{FB}$ and longitudinal polarization fractions $f_L$ for the corresponding decays. Our predictions are consistent with most other theoretical results and experimental data

Read the full abstract

All authors Zhi-Jie Sun, Zhi-Qing Zhang, Shi-Chen Xue, Feng-Zhou Wang

Solar and Stellar Astrophysics

A Pilot Study to Verify the RR Lyrae Candidates with Vera C. Rubin Observatory Early Alerts

Chow-Choong Ngeow, Anupam Bhardwaj, Sarang Shah et al. (+2 more)

We present a pilot study using the Vera C. Rubin Observatory early alerts to verify RR Lyrae candidates in the Pan-STARRS1, the Dark Energy Survey, and the Next-Generation Virgo Cluster Survey RR Lyrae catalogs. RR Lyrae candidates fainter than 16 mag in the $g$-band in these catalogs were crossmatched with the alerts observed in several deep drilling fields and the M49 field. After excluding alerts with a low number of detections, there are 40 alerts associated with the RR Lyrae candidates. The multiband Rubin-LSST light curves extracted from the alerts verify 32 variables as genuine RR Lyrae, although several were not classified as variable stars in the ALeRCE and Lasair community alert brokers. While ALeRCE and Lasair provide $\sim70\%$ and $\sim40\%$ true variable classification, respectively, we find that $20\%$ of the alert sample are non-RR Lyrae variables. The remaining eight candidate variables do not show typical RR Lyrae light curves and include two active galactic nuclei and two eclipsing binaries. Additionally, we have also found a small number of known variable candidates with no alerts, which would suggest that they are either not RR Lyrae variables or the template images are not yet available for their difference image analysis.

Read the full abstract

All authors Chow-Choong Ngeow, Anupam Bhardwaj, Sarang Shah, Steven Gough-Kelly, Oleksandra Razim

Chemical Physics

Streamlining Analysis and Design of Two-Dimensional Electronic Spectroscopy using Machine Learning

Nicholas I. Hausman, Joseph Kelly, Michael S. Chen et al. (+5 more)

Two-dimensional electronic spectroscopy (2DES) offers unique insights into the coupling between electronic and nuclear motion and dynamics, making it a key technique in diverse fields, including materials science and biology. Obtaining 2DES data requires a series of measurements that involve multiple pulses to construct the full picture – a time-consuming task that often necessitates working with limited or noisy data. Here we introduce a machine-learning based framework that aims to maximize the data that can be extracted from 2DES experiments and provides guidance towards the selection of additional experiments. We design a Gaussian mixture model to learn the underlying spectral density of a system, allowing the extraction of reorganization energies and the extrapolation of the 2DES spectra to other time delays beyond those measured, and demonstrate how our framework can be used to select additional measurements to further improve the accuracy. We show that our approach yields accurate results on a variety of systems, including simulations ranging from photoactive yellow protein in the gas phase to Nile red in benzene to the anionic green fluorescent protein chromophore in water, and experiments on Nile blue in ethanol. Our work provides an efficient route to extract maximum insights from 2DES while incurring minimal experimental costs.

Read the full abstract

All authors Nicholas I. Hausman, Joseph Kelly, Michael S. Chen, Frank Hu, Angela Lee, Andrés Montoya-Castillo, Gabriela S. Schlau-Cohen, Thomas E. Markland

Chaotic Dynamics

Comparing Deterministic and Stochastic Parameter Recovery Algorithms Applied to Chaotic Systems

Ashley Wang, Elizabeth Carlson and Franca Hoffmann

This paper explores the effectiveness of various novel deterministic and traditional stochastic data assimilation (DA) and parameter recovery (PR) algorithms given noisy data from chaotic systems. We use semi-analytic methods to numerically construct synthetic data from the Lorenz '63 and multiscale Lorenz '96 chaotic dynamical systems, adding white noise. Our findings show that, for different noise levels, deterministic PR algorithms paired with deterministic DA algorithms are shown computationally to be overall more accurate and stable than stochastic PR algorithms. Additionally, deterministic PR methods have demonstrated greater speed and efficiency, requiring less computational power than stochastic PR methods. This suggests that future work should consider exploring the full potential of deterministic PR algorithms in the presence of noise.

Read the full abstract

Superconductivity

Time-resolved synchronization analysis of stacked intrinsic Josephson junctions of a cuprate superconductor with frequency-modulated terahertz radiation spectra

Masashi Miyamoto, Keisuke Mizoguchi, Ryota Kobayashi et al. (+3 more)

Terahertz radiation from $\text{Bi}_2\text{Sr}_2\text{CaCu}_2\text{O}_{8+\delta}$ intrinsic Josephson junctions (IJJs) provides an ideal platform to study the synchronization of a macroscopic quantum system. Here, we present a spectral analysis of a frequency-modulated Josephson plasma emitter coupled with patch antennas. In the unmodulated intensity distribution as a function of radiation frequency $I_{\mathrm{UM}}(\omega)$, we observe a double Gaussian peak structure. Crucially, double-peak spectra obtained at a constant bias voltage imply either a rapid temporal distribution of resonances or their simultaneous excitation, driven by the mutual electromagnetic coupling between the IJJ mesa and the antennas. At low modulation frequencies $f_m$, the spectra are well reproduced by the products of $I_{\mathrm{UM}}(\omega)$ and frequency combs, yielding a synchronized relaxation time $\tau_s \simeq 0.28\text{ ns}$. Incorporating $\tau_s$ quantitatively reproduces a drastic spectral transformation observed around $f_m \sim 1\text{ GHz}$, unveiling the sub-nanosecond non-equilibrium dynamics of coupled Josephson plasma.

Read the full abstract

All authors Masashi Miyamoto, Keisuke Mizoguchi, Ryota Kobayashi, Nozomi Yagyu, Manabu Tsujimoto, Itsuhiro Kakeya

Quantum Physics

Towards Entanglement-Enhanced Atom Interferometry Using Bow-Tie Cavities

Christian Mancini, Marco Malitesta, Tommaso Mariani et al. (+7 more)

Atom interferometers are among the most sensitive instruments for precision measurements and tests of fundamental physics. Their performance, however, is ultimately limited by quantum projection noise when uncorrelated atomic ensembles are employed. Cavity-assisted generation of entangled states has proven to be a promising route toward quantum-enhanced interferometry beyond the standard quantum limit. In this work, we present the realization and characterization of a monolithic bow-tie cavity developed to achieve a strong collective atom-light coupling with strontium atoms. Unlike conventional standing-wave Fabry-Pérot resonators, the traveling-wave geometry of the bow-tie cavity provides homogeneous atom-light coupling over the entire atomic ensemble, making it particularly suitable for entanglement-enhanced atom interferometry with freely falling atoms. The monolithic cavity architecture presents several scientifically relevant features such as high mechanical stability, high finesse, robustness against mirror misalignment, optical and atomic access and the option of generating squeezed states through different strategies. The cavity was realized for operation on the strontium $(5s^2) ^1S_0-(5s5p) ^3P_1$ transition at 689 nm and achieves a finesse of $\mathcal{F}=5.7\times 10^4$ while keeping the transmission of a single mirror sufficiently large to allow for efficient atomic information extraction. In this geometry, the cavity supports two foci with waists of 164 $\mu$m and 31 $\mu$m which gives access to different regimes of atom-cavity coupling. For ensembles containing up to $10^5$ atoms, the cavity is expected to enable a Wineland squeezing parameter $\xi^2$ of 24 dB through cavity-feedback squeezing, and 28 dB through quantum non-demolition measurements, demonstrating its potential as a platform for next-generation quantum-enhanced atom interferometers.

Read the full abstract

All authors Christian Mancini, Marco Malitesta, Tommaso Mariani, Annalisa Pappalardo, Giuseppe Vinelli, Paolo Vezio, Gabriele Rosi, Enrico Meli, Leonardo Salvi, Guglielmo Maria Tino

Tuesday 16 June

Materials Science · Cross-listed from cs.CE

datascribe_api: Enabling Data-Driven Materials Discovery with DataScribe

Doğuhan Sar{\i}türk, Raymundo Arróyave and Vahid Attari

datascribe_api is a Python library and command-line interface (CLI) that gives researchers programmatic access to DataScribe Cloud, an AI-native platform for materials design and discovery. DataScribe integrates two data services: user-managed scientific data tables, where research groups store experimental measurements, simulation outputs, and derived features; and curated materials science databases from the Materials Project, AFLOW, and OQMD. datascribe_api exposes both through a single, typed Python interface, so researchers can retrieve, filter, and analyze data without writing custom HTTP code. The library handles authentication, connection management, and transient network errors automatically. It exposes nine query endpoints as ordinary Python method calls. Filter conditions use standard Python comparison syntax and are passed as a list, keeping query logic readable without format-specific boilerplate. Pydantic models validate all API responses at parse time, so schema mismatches surface as exceptions rather than silent wrong values. Each result collection converts to a pandas DataFrame in a single call, so retrieved data is directly available for machine learning and statistical analysis. Every materials search result carries a provenance field identifying its source database, satisfying FAIR traceability requirements. The library includes a CLI that exposes all nine endpoints as subcommands, using Typer for argument parsing and Rich for terminal output. Every subcommand supports machine-readable JSON output for shell pipelines and LLM agents. Pre-built wheels for Python 3.11 and later are published on PyPI under the GPLv3 license for Linux, macOS, and Windows.

Read the full abstract

Computational Physics

Characterization of Thermal Systems from Noisy and Low-resolution Measurements Using Dynamic Mode Decomposition

M. E. P. Silva, L. S. Araujo, F. T. Colombo et al. (+2 more)

Thermal monitoring in practical applications is often constrained by sparse sensing, measurement noise, and limited spatial resolution, which hinder the identification of heat transfer dynamics. In such settings, calibrating high-fidelity physical models is computationally demanding, motivating data-driven approaches. Dynamic Mode Decomposition (DMD) provides a framework for extracting spatiotemporal structures from measurement data, but its standard formulation is sensitive to noise and degraded observations. This chapter examines the use of DMD under these constraints, focusing on preprocessing and truncation strategies that affect stability and interpretability. Two cases are considered: forced convection with thermocouple data and transient heat conduction from degraded thermal images. The number of retained modes is treated as a modeling parameter that governs the trade-off between reconstruction fidelity and noise sensitivity. The results indicate that DMD recovers dominant thermal behavior from both sparse and degraded datasets when the truncation level is appropriately selected. Low-rank models provide stable but simplified descriptions, while higher-rank models improve spatial detail at the cost of increased noise sensitivity.

Read the full abstract

All authors M. E. P. Silva, L. S. Araujo, F. T. Colombo, A. Cunha Jr, S. da Silva

Atmospheric and Oceanic Physics

Predictive Modeling of High-Altitude Clear Air Turbulence in the United States: A Machine Learning Approach

Kadir Gokdeniz and Irem Ulku

High-altitude Clear Air Turbulence (CAT) poses significant risks to aviation safety due to its unpredictability and challenges in detection. This study leverages machine learning models to improve CAT prediction within U.S. airspace at 200-350 hPa pressure levels, utilizing Pilot Reports (PIREPs), ERA5 reanalysis data, and aircraft aerodynamic parameters from the BADA database. Gradient boosting algorithms, particularly XGBoost, achieved the highest performance with an AUC of 0.904, demonstrating superior capability in capturing non-linear atmospheric dynamics. Key findings highlight the dominance of geographic coordinates (17.5% feature importance) and turbulence indices like TI3 in prediction, emphasizing the role of regional topography and upper-tropospheric instability. The integration of aerodynamic features such as drag force and wing loading improved the detection of moderate-to-severe perceived turbulence intensity (POD improved from 0.845 to 0.866), providing additional value to traditional aircraft-independent methods. Seasonal analysis revealed winter months as peak periods for CAT incidents, correlating with jet stream activity. While results align with global studies, limitations include geographic scope and aircraft-type diversity. This research underscores the potential of machine learning for operational CAT forecasting, with recommendations for future work focusing on global data integration and real-time telemetry to address climate-driven turbulence trends.

Read the full abstract

General Physics

Solar System and Atomic Clock Bounds on Locally Coupled Swampland Scalars

Suraj Gavhale, Maxim Khlopov, Oem Trivedi et al. (+1 more)

We study how local measurements constrain light scalar fields that are relevant in late time cosmic acceleration and are often discussed in connection with swampland criteria. Starting from a scalar-tensor framework, we define the swampland slope and curvature variables in the canonically normalized Einstein frame and relate them to Solar System tracking, Lunar Laser Ranging, equivalence principle tests and atomic clock comparisons. These measurements do not constrain the scalar velocity by itself, but products of that velocity with microscopic couplings to matter, gravity and atomic parameters. For coupling directions visible to local experiments, the scalar is driven into an ultra slow present regime. This severely restricts the possibility of realizing an $\mathcal{O}(1)$ de Sitter gradient through unscreened visible sector couplings alone. The refined de Sitter alternative remains possible, but in the single field hilltop realization it requires proximity to the maximum or a tuned suppression of the growing mode.

Read the full abstract

All authors Suraj Gavhale, Maxim Khlopov, Oem Trivedi, Maxim Krasnov

Pattern Formation and Solitons

Resonance phenomena in kink antikink collisions within higher order shifted periodic high order models

Teboho Abram Moloi

We investigate kink antikink collisions in higher order scalar field theories described by the higher order models and their shifted periodic extensions. Both classes of models possess three degenerate vacuum states and support topological kink solutions with asymmetric profiles and algebraically decaying tails. By extending conventional polynomial potentials across multiple spatial sectors, we construct shifted periodic high order field theories and examine how this modification affects the scattering dynamics of topological defects. The primary objective of this study is to provide a comparative numerical analysis of kink collisions in the standard and shifted periodic versions of these higher order models. Using direct numerical simulations, we determine the critical velocities that separate capture from escape regimes and identify resonance structures associated with energy exchange between translational and internal vibrational degrees of freedom. Particular attention is devoted to the emergence of escape windows, quasi-fractal patterns, and the role of algebraic tails in shaping the collision outcomes. Our results demonstrate that, although the conventional and shifted periodic models exhibit similar kink antikink configurations, important quantitative differences arise in their critical velocities, resonance structures, and scattering characteristics. The findings further confirm that both classes of models support resonant energy transfer mechanisms analogous to those observed in lower order theories, while simultaneously exhibiting novel features associated with higher-order interactions and long range effects. These results contribute to the growing understanding of nonlinear excitations in scalar field theories and provide new insights into the dynamics of topological solitons in shifted periodic systems

Read the full abstract

Plasma Physics

Rise Time Effects of a Portable Inductive Energy Storage Pulse Generator on NO Production in Spark Discharges

Cheng-Hsiao Hsueh, Yu-Hsuan Chen, Chao-Yu Chen et al. (+1 more)

This study investigates pulse waveform adjustment in a portable inductive energy storage (IES) pulsed power system and its effect on nitric oxide (NO) generation in atmospheric spark discharges. While previous studies have focused on pulse energy, pulse width, and repetition rate, the role of rise time remains insufficiently explored. Existing pulse generators with adjustable rise time are also bulky and unsuitable for portable applications. To address these limitations, this study examines rise time control strategies within a compact IES architecture and employs a parallel high-voltage capacitor to generate adjustable waveforms. Optical emission spectroscopy was used to measure excited N2 and NO gamma emissions, and a NO analyzer was used to monitor NO concentration. In addition, electron excitation temperature, plasma-absorbed power, and rotational temperature were estimated to clarify the influence of waveform characteristics on plasma chemistry. The results show that although rise time can be adjusted, it is coupled with pulse width and input energy in the system. Comparative analysis of spectral intensities, NO concentration, electron excitation temperature, and absorbed energy indicates that NO production depends primarily on energy input rather than rise time. Electrode temperature varies only minimally under different waveform conditions, suggesting that NO formation is mainly influenced by electron impact and ionization processes. This work proposes a portable and simplified IES-based high-voltage pulsed power generator, identifies the constraints associated with rise time control, and demonstrates the feasibility of waveform adjustment. The findings clarify the dominant mechanisms governing NO generation and provide a reference for the design of future portable plasma-based NO production systems.

Read the full abstract

All authors Cheng-Hsiao Hsueh, Yu-Hsuan Chen, Chao-Yu Chen, Yun-Chien Cheng

Soft Condensed Matter

Spectral Leakage and Masking Effects in the Measurement of Hyperuniformity

Yang Jiao

The detection of hyperuniformity relies critically on accurate characterization of the small-wavenumber behavior of the static structure factor of the system. In practice, however, measurements are performed on finite subsystems or through incomplete observations that effectively mask portions of the underlying configuration. Inspired by a recent numerical study [Y. Liu, X. Li, J. Tian, X. Yan, G. Zhang, J. Chem. Phys. 164, 094102 (2026)], we develop a unified theoretical framework that quantifies how finite windows and spatially correlated binary masks modify the observed structure factor. We show that the measured structure factor $S_{obs}(k)$ is the convolution of the intrinsic structure factor with the spectral density of the observation function, whether it is a compact window or an extended random mask. For generic hyperuniform systems with small-$k$ scaling $S(k)\sim k^{\alpha}$, finite observation window induces a universal quadratic leakage term at sufficiently small wavenumbers (i.e., $k \lesssim 1/L$), leading to an apparent $k^{2}$ scaling independent of the true exponent. The true hyperuniform exponent $\alpha$ can only be measured in the intermediate regime $1/L \ll k \ll q_c$. In stealthy hyperuniform systems, where the intrinsic structure factor possesses a spectral gap, all observed small-$k$ power arises entirely from this convolution mechanism. For spatially correlated masks, we derive the corresponding convolution relation in terms of the mask spectral density and identify conditions under which hyperuniform signatures are suppressed, preserved, or distorted. Our results establish quantitative criteria for reliably extracting intrinsic scaling exponents and distinguishing genuine hyperuniform order from measurement-induced artifacts.

Read the full abstract

Mesoscale and Nanoscale Physics

Field-like Perturbation Enabled Six-state Readout in Triaxial $\alpha$-$\mathrm{Fe}_{2}\mathrm{O}_{3}$|Pt Bi-layers

Aditya A. Wagh, Shwetha G. Bhat, Krishna Jha et al. (+2 more)

Canted antiferromagnet $\alpha$-$\mathrm{Fe}_{2}\mathrm{O}_{3}$|Pt bilayers offer a platform for multistate memory, but spin Hall magnetoresistance (SMR) readout cannot distinguish states separated by $180^{\circ}$, limiting detection to three states. We show that a field-like perturbation lifts the degeneracy of opposite states in $\alpha$-$\mathrm{Fe}_{2}\mathrm{O}_{3}$, enabling the resolution of six states in the SMR signal. We introduce a dual-modulation SMR method to mitigate thermal drifts and enable reliable readout. Computations of first- and second-harmonic SMR reveal the role of exchange, anisotropy and field-like perturbations in resolving the states.

Read the full abstract

All authors Aditya A. Wagh, Shwetha G. Bhat, Krishna Jha, Aiswarya Sukumaran, P. S. Anil Kumar

Instrumentation and Detectors

Scene-based field validation of wearable light loggers

Burcu Gemici, Niloufar Tabandeh, Cansu Ozkucukler et al. (+3 more)

Wearable light loggers are increasingly used to measure personal light exposure. However, there is no standardised method to test how well these devices perform in real-world settings. To address this, we developed a scene-based field validation framework combining wearable light loggers, laboratory-grade spectral reference instruments, and image-based scene characterisation to evaluate wearable performance in the field. We applied the validation framework to ActTrust2 and ActLumus light loggers using 433 natural, everyday scenes across two sites: Tübingen, Germany (n=210), and Izmir, Türkiye (n=223), spanning indoor and outdoor environments in daylight, artificial light and mixed scenarios, across wide range of photopic and melanopic equivalent daylight illuminances. Both light loggers exhibited high agreement with the reference instruments (R^2=0.988-0.990), but they systematically underestimated light exposure. The lighting condition, scene complexity, time of day, and study site contributed significantly to measurement bias. Resampling under specific lighting conditions indicated that bias ranged from -0.065 log units in daylight-only situations to -0.195 log units in artificial-only situations. This suggested that single-condition assessments with limited spectra or scene categories can underestimate or overestimate overall wearable performance. Bootstrap resampling demonstrated that performance estimates stabilised at approximately 100 scenes, indicating that a diverse sample of this size is sufficient for reliable field validation. Finally, cross-site validation showed consistent performance across two sites, supporting the framework's reproducibility. Overall, these findings establish our validation framework as an effective tool for guiding scene diversity and sampling design for ecologically valid field validation of wearable light loggers.

Read the full abstract

All authors Burcu Gemici, Niloufar Tabandeh, Cansu Ozkucukler, Johannes Zauner, Altug Didikoglu, Manuel Spitschan

Physics and Society · Cross-listed from cs.AI

Escape from Delusional Echo Trap: Symmetry Breaking, Stochastic Dynamics and Mathematical Mitigation Strategies for Algorithmic Sycophancy

Sayantari Ghosh, Saumik Bhattacharya and Partha Pratim Chakrabarti

We propose a rigorous and systematic mathematical framework for tracking the cognitive trajectories of a user, in the context of algorithmic sycophancy and AI-driven delusional spiraling. Using tools from dynamical systems theory and stochastic differential equations, we explore how individuals perceive, interpret, and update their beliefs as they interact with AI chatbots that possess hidden traits of sycophancy. We treat the evolving conviction as a continuous log-odds state variable, coupled into a stochastic differential equation, navigating a multi-valley potential energy landscape. Our analysis reveals several critical observations governing the stability and rigidity of belief dynamics. We demonstrate that the baseline prior perception of the individual is systematically enhanced by sycophantic feedback beyond a critical threshold. Here, the perceptual potential landscape undergoes a structural phase transition that severely deepens any incremental initial tilt present in the baseline state, transforming the landscape and giving rise to deep, highly resilient attractor basins that trap the individual in unshakeable, self-reinforcing, delusional convictions. Finally, we demonstrate that genuine external information can successfully challenge these rigid states. If this incoming evidence is strong and authentic enough to overcome the internal feedback barrier, it can correct the structural asymmetry caused by sycophancy, inducing a perception reversal that successfully restores the objective belief state.

Read the full abstract

Space Physics

Emissivity of oxidizing titanium in simulated atmospheric entry flows

Andrea Fagnani, Bernd Helber, Annick Hubin et al. (+1 more)

The aerothermal demise of titanium components plays a critical role in the uncontrolled re-entry of space debris from low-Earth orbit. Exposure to high temperatures and dissociated oxygen environments promotes rapid oxidation, significantly influencing the material degradation and surface thermal balance. This study presents time-resolved infrared emissivity measurements of both Grade 2 and Grade 5 titanium samples across five wavelength bands during exposure to entry-relevant conditions simulated in the Plasmatron facility at the von Karman Institute for Fluid Dynamics. The results reveal a dynamic evolution of emissivity throughout the test, including a pronounced drop associated with a characteristic surface temperature jump that is not captured in existing literature data. Post-test electron microscopy highlights a diverse oxide layer morphology at the microscale. Although plasma wind tunnel experiments reproduce only a subset of flight-relevant phenomena to space-debris entry, these findings demonstrate that the complex coupling between oxidation and surface radiative behavior is not adequately captured by conventional pre- and post-test analyses, highlighting their limitations in resolving in-situ emissivity evolution.

Read the full abstract

All authors Andrea Fagnani, Bernd Helber, Annick Hubin, Olivier Chazot

High Energy Physics (Experiment)

The ESSnuSB Experiment

Monojit Ghosh

In this proceedings, we will describe the physics program of the ESSnuSBplus, phase-I of the ESSnuSB project. ESSnuSB is a future long-baseline neutrino oscillation experiment in Europe which aims to measure $\delta_{\rm CP}$ at the second oscillation maximum with with unprecedented precision. Apart from studying the beam based physics, the large far detector is also capable of studying various other physics cases involving solar, atmopsheric and supernova neutrinos. Under the ESSnuSBplus project, there will be a low energy monitored beam and a low energy nuSTORM facility for the measurement of cross-section.

Read the full abstract