Instrumentation and Detectors
On-chip Bragg peak extraction from MHz frame rate X-ray detectors using a cellular automaton architecture
S. Fowler, S. Strempfer, D. Beniwal et al. (+13 more)
High-frame rate pixel detectors can produce data volumes that exceed available off-chip bandwidth, yet in many applications only a sparse subset of each frame carries relevant information. Spatially localized events, including diffraction peaks in crystallography, particle hits in tracking detectors, fluorescence spots in biological imaging, and other applications, all require that clusters of above-threshold pixels be identified and extracted from an otherwise featureless background. Conventionally this is performed in software
algorithms such as connected-component labeling on full frames, but at MHz frame rates the resulting throughput becomes prohibitive. We present a lightweight hardware architecture that performs peak localization and patch extraction directly in the sensor silicon, transmitting only small pixel patches rather than complete frames. FPGA-based testing on an AMD Alveo V80 validated the synthesizability and timing closure of the peak-finding module in real hardware. The design replaces global connected-component labeling with a cellular automaton that uses purely local, fixed-iteration neighborhood operations, eliminating the label storage and equivalence-resolution logic that make conventional approaches impractical on-chip. We validate the architecture on X-ray Bragg peak detection for far-field high-energy diffraction microscopy and show that every peak found by a software reference is recovered, with equivalent downstream reconstructions. The architecture sustains several-hundred-kHz frame rates in 130nm CMOS and exceeds 1MHz in 28nm.
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All authors S. Fowler, S. Strempfer, D. Beniwal, M. Hammer, H. Shi, S. Gnanasekaran, N. Contini, T. Guruswamy, Y. Chen, L. Rota, D. Doering, A. Dragone, T. Zhou, M. Cherukara, K. Yoshii, A. Miceli
Cosmology and Nongalactic Astrophysics
Towards end-to-end Bayesian forward models in global 21-cm cosmology: surrogate modelling and marginalisation of beam uncertainty
Jacob L. Tutt, Dominic J. Anstey, John Cumner et al. (+3 more)
Robust statistical inference in global 21-cm cosmology requires end-to-end uncertainty quantification that jointly handles the highly degenerate cosmological signal, foreground emission, and instrumental response. Although electromagnetic simulations capture physical
antenna properties in a parametrised way, multi-hour runtimes make their integration within likelihood-based sampling frameworks infeasible. Most existing approaches therefore assume a single precomputed beam, a fragile assumption given our demonstration that realistic mismatches can severely bias the recovered cosmological and foreground parameters. To address this, we present an accelerated and differentiable
Bayesian framework that incorporates an informed surrogate representation of chromatic beam uncertainty directly into a forward-modelling pipeline. Treating the physical
antenna properties as nuisance quantities, we apply a two-stage decomposition directly to simulated directivity patterns, reducing the instrumental parameterisation by two orders of magnitude while retaining the angular and spectral structure required for accurate beam reconstruction. Exploiting the linearity of the resulting surrogate, we use analytical marginalisation to allow the continuous instrumental uncertainty to be propagated into the final posteriors and
Bayesian evidence without directly sampling the beam space. Testing the framework against a suite of unseen beams and cosmological signals, we recover the true inputs at approximately the instrumental-noise level. We further show that, for the uncertainty considered here, as few as 100 electromagnetic simulations are sufficient to construct an effective surrogate, substantially reducing the simulation burden for future analyses. This framework provides a scalable, statistically rigorous route towards hardware-accelerated uncertainty quantification in global 21-cm cosmology.
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All authors Jacob L. Tutt, Dominic J. Anstey, John Cumner, Harry T. J. Bevins, Jean Cavillot, Eloy de Lera Acedo
Quantum Physics
Subsystem Symmetries and Fracton Models in Quantum Error Correction
Giovanni Canossa
Constructing new
quantum codes and understanding their error resilience are central challenges in the development of robust
quantum memories. Topological codes are particularly promising due to their favorable error-correcting properties and their connections to phases of matter in many-body physics. In this thesis, we explore the interplay between classical Ising models and
quantum error correction through subsystem
symmetries, fracton topological order, and Kramers-Wannier-type duality. We study two three-dimensional classical self-dual Ising models with subsystem
symmetries, the Tetrahedral Ising model and the Fractal Ising model, investigating their thermal behavior, their relation to fracton phases through subsystem-
symmetry gauging, and the properties of the resulting fracton codes. Using a statistical-mechanical mapping, we determine the optimal code-capacity threshold of the Checkerboard code to be $0.107(3)$, which saturates the theoretical limit for CSS codes and represents the highest optimal error threshold among known three-dimensional codes. We relate this saturation to a generalized
entropy relation for classical
spin models satisfying a Kramers-Wannier-type duality, and argue how this prediction extends to CSS codes with zero encoding rate whose $X$- and $Z$-noise models map to classically dual
spin models. These findings establish fracton codes as highly resilient candidates for
quantum memories and demonstrate the power of the statistical-mechanical framework, together with its duality predictions, in analyzing and constructing robust
quantum error-correcting codes.
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Mathematical Physics · Cross-listed from math.AP
Long Range Asymptotics for the Quadratic Aharonov-Bohm NLS
Piero D'Ancona and Tohru Ozawa
We study the long range behavior of solutions to $i\partial_tu=H_\alpha u+\lambda|u|u$ on $\mathbb R^2$, where $H_\alpha$ is the Friedrichs realization of the Aharonov-Bohm
Hamiltonian with a single pole. The logarithmic phase of the long range ansatz may push a profile out of the domain of $H_{\alpha}$. We characterize profiles that stay in the operator domain by the vanishing of boundary traces at 0 of order $\le \frac 12$; at half flux $\alpha=\frac 12$, no nonzero trace survives. However, every profile in the full domain of $H_{\alpha}$ with small $L^\infty$ amplitude determines a unique global solution with a modified final state, with a remainder rate $t^{-b}$ for all $0<b<1/2+\nu_\alpha$, $\nu_\alpha=\min\{\alpha,1-\alpha\}$. For profiles satisfying the vanishing trace condition, the rate improves to every $0<b<1$. This result is sharp in the sense that, if $\alpha\neq \frac 12$, we can construct profiles with an error of size $t^{-1/2-\nu_\alpha}\log t$, ruling out all faster rates. The upper bound comes from a retarded Strichartz estimate for a residual that is not in $L^2$; the lower bound is an explicit calculation via Hankel transforms. For smoother profiles we also compute the first correction, which gives remainder rates with $1<b<2$.
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High Energy Physics (Theory)
Perturbative Hairy Black Branes in the $G_{2}$-Invariant Sector of Dyonic ISO(7) Gauged Supergravity
Sangheon Yun
We construct perturbative black-brane solutions carrying neutral scalar hair in the $G_{2}$-invariant truncation of four-dimensional dyonic $\mathcal{N}=8$ ISO(7) gauged supergravity, an exact consistent truncation of massive type~IIA supergravity on $S^{6}$. Expanding around the $G_{2}$-symmetric AdS$_{4}$-Schwarzschild black brane in powers of a dimensionless scalar-charge parameter $\eps$, we show that the perturbation hierarchy reduces, order by order, to a nested sequence of inhomogeneous Legendre equations (demonstrated through second order). The first-order scalar satisfies a Pöschl–Teller equation with exact parameter $\nu(\nu+1)=2/3$, giving $\nu=-\frac{1}{2}+\frac{\sqrt{33}}{6}$, and the first-order metric is fixed algebraically by the same function, $A^{(1)}=-\tfrac{\sqrt{7}}{2}\phi^{(1)}$, so the entire $\mathcal{O}(\eps)$ sector is one Legendre function. An identity $\nu+1=\Delta_{+}/3$, with $\Delta_{+}=(3+\sqrt{33})/2\approx 4.372$ the conformal dimension of the dual scalar operator, relates the Pöschl-Teller parameter to the AdS/CFT dictionary via the nonlinear Fefferman-Graham map $z \propto z_{\mathrm{FG}}^{3}$. The $\mathcal{O}(\eps^{2})$ back-reaction yields explicit corrections to the renormalized free energy and Bekenstein-Hawking
entropy density at fixed temperature, consistent with the first law; equivalently, at fixed
entropy or energy density it lowers the Hawking temperature by $\delta T/T=\mathcal{O}(\eps^{2})$. For the leading transport coefficients the shear viscosity saturates $\eta/s=1/(4\pi)$, while the Eling-Oz horizon formula gives a nonzero bulk viscosity $\zeta/\eta=\bigl(\tfrac{\Delta_{+}-3}{2}\bigr)^{2}\eps^{2}=\tfrac{3(7-\sqrt{33})}{8}\eps^{2}\approx0.471\,\eps^{2}$. With $c_{s}^{2}=\tfrac12-\mathcal O(\eps^{2})<\tfrac12$, this indicates a softening of the equation of state.
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High Energy Astrophysical Phenomena
Constraining Cosmic-Ray Acceleration and Escape in Middle-Aged Supernova Remnants with GeV-TeV Gamma-Ray Observations
Siyu Chen, Bing Theodore Zhang, Yi Xing et al. (+2 more)
In this work, we perform a systematic, time-dependent study of the gamma-ray emission from four representative middle-aged SNRs (W51C, IC~443, W44, W28), incorporating both CRs within the remnant shells and escaped CRs interacting with surrounding molecular clouds. We compare our results with GeV–TeV gamma-ray observations from
Fermi-LAT, H.E.S.S., MAGIC, and LHAASO, including a dedicated analysis of the
Fermi-LAT data for regions A and B associated with W28. We find that the observed spectra favor steeper CR injection spectra with indices of \(\alpha\sim4.2\)–\(4.3\), maximum
proton energies of $\sim$ \(100\)–\(300\) TeV,
diffusion coefficients below the
Galactic average, and CR acceleration efficiencies from a few to tens of percent. In particular, the VHE emission detected by LHAASO from W51C is more naturally explained by escaped CRs interacting with a nearby molecular cloud. We also investigate the contribution of escaped CRs to the VHE emission from IC~443, W44, and W28. We further demonstrate that escaped CRs can substantially enhance the TeV
neutrino flux from middle-aged SNRs, improving their prospects as potential
neutrino sources. These results provide new constraints on CR acceleration and escape in middle-aged SNRs and highlight the important role of escaped CRs in shaping their high-energy gamma-ray and
neutrino emission.
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All authors Siyu Chen, Bing Theodore Zhang, Yi Xing, Siming Liu, Xunxiu Zhou
Instrumentation and Methods for Astrophysics
Asgard/NOTT: Status of laboratory nulling performance
T. Mattheussen, R. Laugier, D. Defrère et al. (+26 more)
Nulling interferometry enables the direct detection of faint companions and circumstellar structures at angular separations unresolvable by classical, diffraction-limited imagers, whilst dramatically improving the measurable contrast. The Asgard/NOTT nulling instrument aims to achieve a contrast performance of 10^-5 in the L' wavelength band (3.5 - 4.0 {\mu}m), enabling observation and characterization of young
giant exoplanets near the snowline and hot exozodiacal
dust. Previous studies have verified the nulling capabilities, of the chip in ambient conditions and of the test bench in cryogenic conditions. This work aims to add the first ambient performance assessment of the test bench with spectrally dispersed light. Necessary revisions are made to the data acquisition and calibration pipeline and fringe scans are carried out, modeled and fitted. The splitting ratios of the 4-
telescope nulling beam combiner, a photonic Gallium Lanthanum Sulfide (GLS) chip, are moreover characterized on the bench, showing tentative agreement with previous chip characterization. The null performance has worsened, the achieved contrast of ~ 10^-1 being one order of magnitude higher than what earlier characterized performance showed. Multiple future changes to the test bed and to the approach taken promise an improved characterization of performance. In particular, the input beam intensities will be deliberately mismatched to account for the imbalanced splitting ratios of the directional couplers. With the installation of the final cryostat and camera, the developed tools will be leveraged to re-assess the performance in ambient and cryogenic conditions.
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All authors T. Mattheussen, R. Laugier, D. Defrère, G. Garreau, P. Chingaipe, G. Raskin, M. Salman, K. Missiaen, B. Vandenbussche, W. Verstraeten, J. Morren, A. Kuriakose, M. Ireland, M.-A. Martinod, A. Sanny, S. Gross, L. Labadie, A. Bigioli, A. Jóo, S. Madden, A. Mazzoli, G. Medgyesi, S. Ertel, T. A. Stuber, J. P. Scott, S. Kraus, F. Martinache, X. Haubois, N. Schuhler
Quantum Physics
An ultra-bright, highly-scalable, squeezed light source for hybrid quantum photonics
Kai-Hong Luo, Denis Kopylov, Florian Lütkewitte et al. (+8 more)
Hybrid
quantum photonics seeks to combine the complementary advantages of continuous- and discrete-variable
quantum optics. This typically entails
photon-counting measurements on entangled states generated by interfering many single-mode squeezed-
vacuum (SMSV) states. However, because conventional
photon-counting schemes are mode-insensitive, it is critical that the SMSV states occupy a single, well-defined mode. Achieving this requires careful engineering of the process, which determines both the spatial and spectro-temporal properties of the generated state. In addition, the ideal source must be massively scalable, capable of efficiently generating strong squeezing, and remain compatible with existing detection schemes and fiber networks. Although many platforms address one or more of these requirements, satisfying all of them simultaneously remains challenging. Here, we present a source that meets all of these requirements: a single-pass, periodically poled, Type-II potassium titanyl phosphate (KTP) waveguide optimized for scalable hybrid
quantum-photonic architectures. The SMSV state produced by the source has a measured effective mode number of 1.24. Furthermore, the source is extremely bright (producing up to 40 000
photons per pulse) and operates at a central wavelength of 1546nm, optimized for fiber-network compatibility and which, in combination with picosecond duration, also enables intrinsic
photon-number resolution in superconducting nanowire single-
photon detectors. Although this source constitutes an ideal source in a simplified picture, the ultimate limitations of any source will be governed by complex dynamics that arise when the system is driven at high-gain or due to unavoidable loss during state generation. We have therefore developed a complete theoretical framework that enables a comprehensive
photon-counting-based characterization of the source.
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All authors Kai-Hong Luo, Denis Kopylov, Florian Lütkewitte, Jan-Lucas Eickmann, Simone Atzeni, Fabian Schlue, Benjamin Brecht, Torsten Meier, Polina Sharapova, Michael Stefszky, Christine Silberhorn
High Energy Physics (Phenomenology)
Three-body forces in the quark model
Jongheon Baek, Aaron Park, Emiko Hiyama et al. (+4 more)
We review the connection between constituent-
quark Hamiltonians and QCD and investigate the long-standing difficulty of describing
meson and
baryon spectra with one common two-body interaction. A
Hamiltonian calibrated to ground-state
mesons leaves systematic
baryon mass residuals, largest in the light-
quark sector and decreasing toward heavier
flavors. We show that a short-range, color-
spin-dependent connected three-
quark interaction substantially reduces this incompatibility. Mass-scaled finite-range profiles yield high-accuracy
baryon spectra, whereas
flavor-independent common-range profiles do not remove the residual
flavor pattern. The result is tested on additional ground-state
baryons outside the calibration set and through
meson–
baryon compatibility analyses across several alternative
quark-model
Hamiltonians. We also
benchmark radial and orbital excitations to identify the regime in which a static compact valence
Hamiltonian remains reliable, and provide explicit color-
spin matrix elements for two- and three-body operators in
baryons and multiquark configurations. Within the tested valence-space representations, the results indicate that a mass-dependent short-range connected three-
quark interaction provides the missing contribution required for a consistent simultaneous description of
meson and
baryon ground-state spectra.
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All authors Jongheon Baek, Aaron Park, Emiko Hiyama, Sungsik Noh, Hyeongock Yun, Kyong Chol Han, Su Houng Lee
Quantum Physics
AlphaClifford: Efficient Clifford Synthesis and Transpilation with Model-based RL
Daniele Lizzio Bosco, Jacopo Cossio, Carla Piazza et al. (+1 more)
Clifford
circuits play a foundational role in
quantum computing, particularly due to their importance in
quantum error correction and fault-tolerant logical synthesis. While these
circuits can be efficiently simulated and represented as
symplectic matrices, standard synthesis methods-such as the Aaronson-Gottesman
algorithm-often yield sub-optimal
circuits with excessively high gate counts. In this work, we introduce AlphaClifford, a model-based Reinforcement Learning framework powered by Monte Carlo Tree Search, designed to efficiently synthesize Clifford
circuits from the fundamental gate set composed of H, S, and CNOT. By modeling the state space through the algebraic properties of the
symplectic group, AlphaClifford effectively explores this combinatorial space to minimize overall
circuit cost. For unconstrained Clifford optimization, our approach achieves a consistent reduction in both total and two-
qubit (CNOT) gate counts compared to state-of-the-art synthesis heuristics, despite operating with a strictly less expressive gate set. Furthermore, we demonstrate the broad applicability of our framework on two additional tasks: hardware-constrained Clifford transpilation, where we outperform existing RL-based compilers, and as a post-synthesis optimization component within a full Clifford+T logical synthesis pipeline. Our results underscore that model-based RL is highly effective at addressing the combinatorial complexities of
quantum compilation, offering a scalable pathway to mitigate hardware constraints in both near-term and future fault-tolerant
quantum devices.
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All authors Daniele Lizzio Bosco, Jacopo Cossio, Carla Piazza, Giuseppe Serra
Mesoscale and Nanoscale Physics
Flat and Topological Floquet Minibands from Patterned Light in Untwisted Bilayer Graphene
Muhammad Faisal and Michael Vogl
Two-dimensional superlattices in van der Waals materials host flat bands and nontrivial
topology, most famously at the so-called magic angles of twisted
bilayer graphene, where flat bands give rise to correlated and topological phases. Yet these superlattices are usually created by twisting the layers or applying strain, and once a sample is fabricated, their period is fixed and extremely difficult to tune. Here we propose an alternative route: imprint the superlattice optically, using patterned electromagnetic fields rather than a physical twist or strain. We show that patterned in-plane cir- cularly polarized light and a combined drive consisting of a patterned out-of-plane longitudinal field and a uniform circularly polarized field produce isolated bands in both AA- and AB-stacked
bilayer graphene. In AB stacking, the central bands additionally become nearly flat, capturing key features of a driven moire superlattice. In this approach, the superlattice period is set by the illumination and is straightforward to tune, and circularly polarized light breaks time-reversal
symmetry. Computing the valley Chern numbers of the central bands, we find a rich topological structure with several phase transitions in both stackings. Our results establish light-induced superlattices as a flexible and tunable platform for engineering flat bands and topological phases in
bilayer graphene.
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Physics and Society
A Structured Framework for Calibrating Stochastic Car-Following Models: Data Adequacy, Parameter Sensitivity, and Objective Selection
Shirui Zhou, Junzhe Ding, Junfang Tian et al. (+3 more)
Calibrating a
stochastic car-following model is harder than its deterministic counterpart: the loss itself becomes a random variable, so a favorable random realization can be mistaken for a good parameter vector. This paper develops a structured framework for calibrating
stochastic car-following models – a completeness-controlled synthetic design, a corrected variance-based sensitivity analysis (VBSA), and the minimum-realization (MRMIN) calibration protocol – across two structurally different
stochastic mechanisms, QIDM and IDM2D. We test two claims from deterministic calibration – that a small number of parameters, and the trajectory itself above all, dominates the sensitivity ranking, and that spacing calibration keeps dominating speed calibration once dynamics are
stochastic – and ask whether a model's noise term can be calibrated on its own. In a balanced synthetic experiment, driving-regime completeness has a mean total-effect index on par with the model's most influential parameter and roughly two orders of magnitude above pair identity, extending rather than reversing the deterministic finding on trajectory-identity dominance. Under MRMIN, calibrating only the noise parameter against a population-wide deterministic fit more than doubles median spacing error across 1644 NGSIM trajectories, but fitting the deterministic parameters per trajectory first and calibrating noise on top recovers it. Spacing calibration remains more cross-dimensionally robust than speed calibration on average, but the deterministic guarantee that this dominance can never reverse is violated in 19-26% of trajectories for both mechanisms. A multi-objective screen in relative-error space then favors joint spacing-speed goodness-of-fit functions over single-dimension spacing calibration. Deterministic calibration guarantees should therefore be re-tested, not assumed, once a model is
stochastic.
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All authors Shirui Zhou, Junzhe Ding, Junfang Tian, Shiteng Zheng, Rui Jiang, Anci Shi
Quantum Physics
Quantum-Enhanced Atomic Sensor via Spin Nonequilibrium Criticality
Ding Huang, Minwei Shi, Guzhi Bao et al. (+2 more)
The sensitivity of
quantum sensors is fundamentally constrained by the standard
quantum limit (SQL) arising from intrinsic
quantum fluctuations. While non-classical resources like squeezing or
entanglement can surpass this limit, their utility is often restricted by the extreme fragility of entangled states and the complexity of their preparation.
Quantum criticality offers a compelling alternative by harnessing divergent susceptibility to amplify signals without requiring fragile non-classical resources. However, the practical benefit of this approach has remained controversial due to the potential for the simultaneous amplification of
quantum noise. Here, we demonstrate a universal protocol for noiseless critical sensing by engineering a light-driven atomic ensemble near a dynamical critical point. Analogous to a Kapitza pendulum near its inverted orientation, the
spin system enters a non-
equilibrium regime where the signal susceptibility diverges while the
quantum noise periodically recedes to its coherent baseline. We exploit this “noise ebbing” to create a built-in noiseless amplifier, demonstrating a 3.3 dB metrological gain over the SQL in an atomic magnetometer. Our implementation exhibits intrinsic robustness against common experimental imperfections such as detection losses, establishing non-
equilibrium critical dynamics as a practical and versatile paradigm for surpassing the fundamental limits of
quantum sensing.
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All authors Ding Huang, Minwei Shi, Guzhi Bao, Keye Zhang, Weiping Zhang
Plasma Physics
High-power TCV scenario for conventional and alternative divertor studies
K. Lee, C. Theiler, M. Carpita et al. (+20 more)
Alternative divertor configurations (ADCs) must be evaluated under boundary
plasma conditions approaching reactor-level values to be considered a reliable, physics-based solution for tokamak power exhaust. Most ADC experiments performed to date were at relatively low exhaust power. This work presents a high-power scenario on the TCV tokamak enabling the study of a wide variety of divertor
magnetic shapes under an expanded SOL and power exhaust parameter space. The scenario is characterized by high power levels of electron cyclotron resonance heating ($2.5\,\text{MW}$ fully absorbed in a $\sim1\,\text{m}^{3}$
plasma) at high
plasma current (edge safety factor $q_{95}\approx 2.5$), and low upstream separatrix densities ($n_{e,\text{u}}\approx1\times10^{19}\,\text{m}^{-3}$, Greenwald fraction $f_{\text{G}}\approx 0.1$). Stationary parallel heat fluxes up to $100\,\text{MW m}^{-2}$ are measured at the divertor target, an order of magnitude above previous TCV power exhaust studies. The obtained SOL collisionality and Lengyel detachment scaling metric lie within range of values expected in future reactors (SPARC, ITER, ARC).
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All authors K. Lee, C. Theiler, M. Carpita, M. Zurita, P. Sintre, O. Février, F. Pastore, H. Reimerdes, K. Verhaegh, M. Winkel, D. Brida, B.Y.K. Brown, M.J.H. Cornelissen, R. Ducker, G. Durr-Legoupil-Nicoud, D. Hamm, R.I. Morgan, A. Perek, O. Sauter, E. Tonello, Y. Wang, the TCV Team, the EUROfusion Tokamak Exploitation Team
Quantum Physics
Real Classical Shadows with Noise
Atharva Hingane and Dax Enshan Koh
The real classical shadows protocol of West et al. replaces the
unitary (Clifford) ensemble of the Huang–Kueng–Preskill scheme by the orthogonal (real Clifford) ensemble, and for symmetric observables achieves strictly smaller
estimator variances: a factor approaching two for global
evolution and an exponential factor $(3/2)^k$ for $k$-local real Pauli observables. Real hardware, however, never implements the ideal
evolution. Building on the noisy classical shadows framework of Koh and Grewal, we give a complete theory of the real classical shadows protocol in the presence of a known completely positive trace-preserving noise channel acting after the orthogonal
evolution. We derive the noisy global and local orthogonal shadow channels from first principles using the Weingarten calculus of the orthogonal group, prove that each is a depolarizing channel acting on the symmetric (respectively locally symmetric) component of its input, and derive from it the exact single-shot variance in closed form, together with the associated shadow seminorm, two-sided bounds on it, and the resulting sample-complexity guarantees. We prove that the noiseless sample-complexity advantages survive intact under noise. Because the variances are exact rather than bounded, the ratio is controlled by a single dimensionless parameter, which gives a closed-form criterion for when the factor of two is attainable: both the second-moment and the variance ratio reach it exactly when the observable's norm profile grows, and the noise enters that limit only through a factor lying within $2/(d+2)$ of two, so the advantage is uniform in the noise. For rank-one targets it is provably unattainable, saturating strictly below two. The local real-Pauli advantage remains $(3/2)^k$. We treat complex measurement bases through a reality parameter and a transposed-noise scalar, recovering
unitary shadows in the appropriate limit.
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Mathematical Physics
Gaudin models for some classical multivariate distributions
Plamen Iliev
Representations of the Kohno-Drinfeld Lie
algebra associated with several classical multivariate distributions have played an important role in recent developments in the theory of
quantum superintegrable systems. In this work, we analyze the corresponding Gaudin models for the multivariate Hahn, Dirichlet, multinomial, and negative multinomial distributions. More precisely, using tools from representation theory, we construct multivariate orthogonal
polynomials with respect to these distributions as common eigenfunctions of Gaudin operators. The
polynomials are parametrized by solutions to the Bethe ansatz equations or, equivalently, by the roots of Heine-Stieltjes
polynomials.
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History and Philosophy of Physics
Stefan Bergman (1895-1977). Notes on His Bio- and Bibliography
Tilman Sauer
Stefan Bergman worked in the field of pure and applied mathematics and became known primarily for his work on complex analysis of several variables. He studied the theory of solutions to linear partial differential equations via integral operators and introduced the concept of the Bergmann kernel function. He also worked on problems in electrical engineering, the theory of elasticity, potential theory, and hydrodynamics, particularly supersonic flows. His academic career in Germany was cut short by the Nazi purge, leading to a peripatetic exile through the USSR and France before finally establishing a distinguished career in the United States, notably at Harvard and Stanford. The paper sketches his biography based on archival sources and complements a bibliography of his writings compiled by M.Skwarczy'nski in 1981 with a number of references primarily from his early career.
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High Energy Physics (Theory)
Kazunobu Maruyoshi, Hyejung Moon and Jaewon Song
We argue that the non-invertible
symmetry of $\mathcal{N}=4$ super Yang-Mills theory, obtained by combining S-duality, half-space gauging, and R-
symmetry twist, is realized as an outer-
automorphism of the associated vertex operator
algebra. Hence, the Schur and Macdonald index of $\mathcal{N}=4$ super Yang-Mills theory with non-invertible
symmetry twist corresponds to the (refined)
vacuum character of the associated vertex operator
algebra with the outer-
automorphism twist. We provide a few checks of our proposal from the large-$N$ limit and by matching the fusion rules, which involve charge conjugation on local operators. The `charged' Schur index indeed matches the outer-
automorphism-twisted
vacuum character.
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Materials Science
Ultrafast order-selective electron imaging and spectroscopy
Jan Philipp Bange, Till Domröse, Claus Ropers et al. (+2 more)
Ultrafast pump-probe spectroscopies in energy and momentum have become indispensable for probing non-
equilibrium dynamics in
quantum materials, revealing pathways in ultrafast energy conversion and light-induced phase transitions. Different modalities uniquely access the coupled
lattice, charge, and
spin degrees of freedom that underpin the functionality of these materials. However, investigating technologically relevant nanoscale devices also requires high spatial resolution. Although electron microscopy provides nanometer-scale imaging, it frequently lacks the simultaneous ultrafast temporal resolution and spectroscopic specificity needed for such studies. In this perspective, we review recent advances in dark-field electron and photoelectron microscopy, focusing on two complementary techniques: femtosecond photoelectron momentum microscopy and ultrafast transmission electron microscopy. Their application enables comprehensive insights into the ultrafast dynamics of the electron,
lattice, and
spin subsystems. These order-selective electron imaging and spectroscopy techniques open broad scientific opportunities for a microscopic understanding of non-
equilibrium phenomena in
quantum materials, nanostructures and devices.
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All authors Jan Philipp Bange, Till Domröse, Claus Ropers, Stefan Mathias, Marcel Reutzel.
Fluid Dynamics
Mach-disk formation and shock-structure transitions in underexpanded coflowing jets
Ganesh Dhungana, Srijan Satyal and Nek Sharan
The near-field shock structures of underexpanded sonic jets exiting into a subsonic coflow are investigated over a range of nozzle pressure ratio (NPR) and coflow-to-nozzle-exit velocity ratio ($U_c$), representative of a propulsive nozzle in subsonic flight. Time-averaged statistics from fully-resolved axisymmetric simulations and inviscid method-of-characteristics (MOC) analysis are used to understand how coflow alters the shock-
cell structures, in particular the Mach-disk formation. It is well established that increasing NPR transitions the centerline reflection from regular (characterized by oblique shocks) to Mach reflection (characterized by a near-normal Mach disk). We find that coflow has the opposite influence: a strong coflow shrinks the Mach disk until it vanishes, reverting Mach reflection to regular reflection, so the NPR for this transition increases with $U_c$. This effect has previously been attributed to a reduction in the jet-boundary inclination at the nozzle lip, which confines the lip Prandtl-Meyer fan to a smaller angle and weakens the embedded shock. We show instead that this inclination is determined by the non-uniform pressure the coflow imposes along the jet boundary, which is the primary driver of the shock-structure transitions in coflowing jets. The non-uniform pressure weakens the boundary-reflected compression waves and orients them at shallower angles, so the embedded shock reflects regularly or fails to form. A simulation-informed MOC analysis with this non-uniform pressure boundary condition reproduces the transition behavior with increasing coflow. Coflow also lengthens the first shock
cell linearly, which is accurately estimated by a simple correction to Prandtl classical shock-
cell length scaling.
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High Energy Physics (Phenomenology)
$\Upsilon(nS)$ Production within Jets at the LHC
Taewook Ha, Hee Sok Chung, Daekyoung Kang et al. (+2 more)
Heavy quarkonium production inside jets offers a sensitive probe of QCD dynamics and bound-state formation mechanisms. While recent studies demonstrate that charmonium-in-jet observables effectively discriminate among competing nonrelativistic QCD (NRQCD) long-distance
matrix element (LDME) sets, whether this discriminating power persists in the bottomonium sector remains an open question. Here, we present the first phenomenological study of $\Upsilon(1S)$, $\Upsilon(2S)$, and $\Upsilon(3S)$ production inside jets using the fragmenting jet function (FJF) framework at next-to-leading order (NLO), incorporating DGLAP
evolution, threshold resummation, and feeddown contributions from higher bottomonium states. In sharp contrast to charmonium, we find that bottomonium-in-jet momentum-fraction ($z_H$) distributions exhibit a universal shape that is remarkably insensitive to the choice of LDME sets. We show that this universality stems from the strong dominance of the S-wave
spin-triplet color-octet ($^3S_1^{[8]}$) production mechanism reinforced by $\chi_b$ feeddown transitions. Our predictions capture both the characteristic large-$z_H$ peak and the spectral broadening with increasing jet transverse momentum observed in recent CMS measurements. These results establish a clear physical distinction between charmonium and bottomonium fragmentation inside jets, providing a theoretical
benchmark for future high-precision measurements at the LHC.
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All authors Taewook Ha, Hee Sok Chung, Daekyoung Kang, Yunlu Wang, Haixiang Zhu
High Energy Physics (Phenomenology)
Unified spectroscopy of $P$-wave flavor-sextet heavy baryons from QCD sum rules
Shu-Wei Zhang, Xuan Luo, Hua-Xing Chen et al. (+1 more)
We investigate the $P$-wave
flavor-sextet charmed and bottom
baryons within heavy
quark effective theory. A key motivation is provided by the recent evidence for the $\Xi_c(2882)^0$, which completes a sequence of four narrow $\Xi_c$ structures together with the $\Xi_c(2923)^0$, $\Xi_c(2939)^0$, and $\Xi_c(2965)^0$. Their characteristic mass-splitting pattern closely parallels that of the $\Omega_c(3000)^0$, $\Omega_c(3050)^0$, $\Omega_c(3066)^0$, and $\Omega_c(3090)^0$ states, providing strong constraints on their spectroscopic assignments. We classify the seven $P$-wave states in each of the $\Sigma_Q$, $\Xi_Q^\prime$, and $\Omega_Q$ sectors ($Q=c,b$), calculate their masses and intra-doublet mass splittings using QCD sum rules, and study their strong decays using light-cone sum rules. Configuration mixing between states with the same
quantum numbers is also investigated. The combined analysis favors a common interpretation of the four narrow $\Xi_c$ and the four lowest narrow $\Omega_c$ structures in terms of the corresponding $\lambda$-mode excitations. Extending the same framework to the bottom sector, we obtain a coherent picture of the observed $\Sigma_b$, $\Xi_b$, and $\Omega_b$ structures. In particular, the $\Sigma_b(6097)$, $\Xi_b(6227)$, and $\Omega_b(6350)$ structures may each contain an unresolved pair of nearby $P$-wave states. We also predict two additional $\Sigma_b$ states, two additional $\Xi_b^\prime$ states, and one additional $\Omega_b$ state, all of which are expected to be relatively narrow and remain to be identified experimentally.
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All authors Shu-Wei Zhang, Xuan Luo, Hua-Xing Chen, Hui-Min Yang
Instrumentation and Methods for Astrophysics
Demonstration of a multimode-to-multimode photonic lantern for astronomy
Marina Centenera-Merino, Andrew Ross-Adams, Christopher Betters et al. (+14 more)
Photonic lanterns have been widely used in astronomy as low-loss multiplexing devices, typically coupling light from a multimode input into several single-mode outputs. In this work, we present the first multimode-to-multimode photonic lantern specifically designed to combine light from several multimode fibers into a single multimode waveguide. We fabricated and characterized the devices at multiple wavelengths to evaluate the performance of the adiabatic multimode transition. The measured efficiencies exceed $90\ \%$, demonstrating low-loss multimode propagation and efficient modal transfer through the lantern structure. This architecture enables efficient multimode beam combination and represents a significant step toward scalable modular
telescope concepts without requiring diffraction-limited injection.
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All authors Marina Centenera-Merino, Andrew Ross-Adams, Christopher Betters, Pedro J. Amado, Jesus Aceituno, Kalaga Madhav, Stefan Cikota, F. Javier Flores, Julius Göhring, Abani S. Nayak, Jose Luis Ortiz, David Peréz-Medialdea, Francisco J. Pozuelos, Martin M. Roth, Mabel Ruíz-López, Miguel Andrés Sánchez-Carrasco, Sergio Leon-Saval
Disordered Systems and Neural Networks · Cross-listed from cs.LG
On the Slow Convergence to Trivial Solutions of Algorithms for Hard Optimization Problems
Ali Hussaini Umar, Jean Barbier, Matthieu Jonckheere et al. (+1 more)
Hard combinatorial optimization problems, many of which are NP-hard, present fundamental algorithmic challenges. Average-case analysis on random instances has emerged as a powerful framework for understanding typical algorithmic performance beyond worst-case guarantees. A substantial body of work has established negative results: for sufficiently hard instances (often controlled by the underlying graph connectivity/constraints density), no known
polynomial-time
algorithm can significantly outperform naive heuristics in the double asymptotic limit where both problem size and constraints density tend to infinity. We revisit this picture by studying the finite-size behavior of some optimization
algorithms across easy, intermediate, and hard regimes. Through rigorous analysis of large-graph asymptotics combined with numerical experiments on canonical problems (maximum independent set and maximum $K$-SAT), we demonstrate that while
algorithms do eventually converge to theoretically predicted bounds, this convergence can be remarkably slow. In the intermediate regime where instances are already highly constrained, local
algorithms achieve solutions substantially better than their predicted performance in the high-constraint-density limit. This gap between finite-regime and asymptotic behavior has important practical implications: sophisticated algorithmic design remains crucial even when asymptotic theory predicts inevitable failure.
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All authors Ali Hussaini Umar, Jean Barbier, Matthieu Jonckheere, Manuel Sáenz
Materials Science
Detecting Magnetic Phase Transitions in Ion-Irradiated CrSBr Through Resonant Raman Scattering
Daria I. Markina, Alison Pfister, Priyanka Mondal et al. (+9 more)
Controlling
magnetic phases and accurately determining their transition temperatures are essential for the development of low-dimensional
magnetic materials. Here, we demonstrate that He$^+$ ion irradiation provides a versatile route for engineering
magnetic phases in layered CrSBr and establish temperature-dependent polarization-resolved Raman spectroscopy as a sensitive optical probe for identifying irradiation-induced
magnetic phase transitions. We reveal that the
magnetic response of the modified CrSBr is governed by both irradiation dose and
crystal thickness. The temperature
evolution of the Raman tensor elements resolves the
antiferromagnetic transition in pristine CrSBr at T$_N \approx 132$ K as well as irradiation-induced
magnetic transitions at T$_C \approx 105-110$ K and T$_D \approx 40$ K corresponding to
ferromagnetic and defect-related
magnetic phase transitions. Complementary magneto-optical measurements confirm the progressive suppression of
antiferromagnetic order and the emergence of new defect-engineered
magnetic phases, including pure
ferromagnetic behavior at high irradiation doses. These findings establish irradiated CrSBr as a platform for controllable
magnetic phase engineering while demonstrating polarization-resolved Raman spectroscopy as a rapid, non-destructive, and broadly applicable method for probing
magnetic phase transitions in van der Waals magnets.
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All authors Daria I. Markina, Alison Pfister, Priyanka Mondal, Lukas Krelle, Sai Shradha, Regine von Klitzing, Kseniia Mosina, Zdenek Sofer, Fangchao Long, Ulrich Kentsch, Shengqiang Zhou, Bernhard Urbaszek
Optics
Remarkable Enhancement of High Harmonic Generation from Superhard Material under High Pressure
Zishao Wang, Tong Wu, Ziwen Wang et al. (+6 more)
High harmonic generation (HHG) in solids offers a pathway to develop compact extreme ultraviolet (EUV) sources crucial for attosecond science and advanced spectroscopy. Here, we demonstrate theoretically that high pressure dramatically enhances HHG in superhard hexagonal tungsten nitride (h-WN6). Compared with solid-state systems at ambient pressure, the reshaped electronic environment under high pressure leads to a unique band-gap widening in h-WN6, which raises the material's damage threshold, allowing the use of stronger
laser fields and enabling access to higher-energy bands. This pressure-induced band-gap widening offers a promising strategy to overcome the cutoff limitation of solid-state EUV light sources.
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All authors Zishao Wang, Tong Wu, Ziwen Wang, Shicheng Liu, Hui Li, Kun Zhao, Jian Sun, Chao Yu, Ruifeng Lu
Quantum Physics
Quantum Tensor Network Learning with DMRG
Gustav J L Jäger, Martin B Plenio and Hans-Martin Rieser
Tensor Networks are a relatively new machine learning approach. The architectures proposed initially are inspired by approaches from
quantum many-body physics simulations. One common layout is the
matrix product state (MPS) also known as a tensor train optimized with gradient descent techniques. We introduce a global normalization condition, so that the MPS represents a
quantum state. We investigate two optimization methods that find the locally optimal tensors and compare them regarding their effectiveness. One is based on gradient descent and the other on an adaptation of DMRG.
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Astrophysics of Galaxies
The efficient star-forming regions of stripped-envelope supernovae
M. Solar, M. J. Michałowski, J. Nadolny et al. (+13 more)
Massive
stars ($> 8~\rm{M}_{\odot}$) play a key role in shaping the interstellar medium of
galaxies through
stellar feedback. However, how these
stars form and evolve before exploding as core-collapse
supernovae (SNe) remains elusive. We compute for the first time the
star-formation efficiencies (SFEs) at the locations of hydrogen-rich (H-rich) SNe and stripped-envelope SNe (SESNe) to constrain their progenitor properties. We used VLT/MUSE and ALMA observations of H$\alpha$/H$\beta$ and CO(2-1) emission lines to trace the components of the warm ionised gas and cold molecular gas, respectively. Both observations resolve individual H II regions and
giant molecular clouds at spatial resolutions on cloud-scales ($\sim$100 pc). This combined data allows us to compute the SFE from the
star formation rate (SFR) and the molecular gas mass (M$_{\rm{mol}}$) as SFE = SFR/M$_{\rm{mol}}$. We find that SESNe explode in environments that are currently forming
stars eight times more efficiently than those of H-rich SNe (higher SFR for SESNe with similar M$_{\rm{mol}}$). On one hand, this is consistent with the scenario in which the majority of SESNe are produced from very massive
stars ($> 20~\rm{M}_{\odot}$) if the initial mass function is top-heavy. On the other hand, most of SESN progenitor channels are formed from interacting binaries ($< 20~\rm{M}_{\odot}$) if an increased binary system formation rate is connected with turbulences and, in turn, with the boost to SFE. Then, an increased binary fraction could explain the enhanced H$\alpha$ luminosities. In summary, SESNe preferentially occur in regions of intense, efficient
star formation rather than simply higher gas content.
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All authors M. Solar, M. J. Michałowski, J. Nadolny, L. Galbany, J. P. Anderson, J. Sollerman, T. Pessi, E. Zapartas, B. Šlaus, J. Alexander, O. Ryzhov, J. Hjorth, C. Jiménez-Palau, P. Nowaczyk, D. Somawanshi, A. Leśniewska
High Energy Physics (Phenomenology)
Triangle Feynman diagram in the timelike region
Mikhail A. Ivanov, Dmitri Melikhov and Silvano Simula
In
Quantum Field Theory, triangle Feynman diagram $F(p_1^2,p_2^2,p_3^2|m_1,m_2,m_3)$ is an analytic function of its variables, whose analytic structure is fully determined by the location of singularities of the propagators of particles in the loop. The form factor $F(p_1^2,p_2^2,p_3^2|m_1,m_2,m_3)$ is easily calculable in the Euclidean region of all variables, $p_i^2<0$, $i=1,2,3$. A rigorous way to obtain the form factor in the timelike region is to perform the analytic continuation from the Euclidean region using single or double dispersion representations. On the other hand, there is a simple representation of the triangle as integral over Feynman parameters. We show that all known rigorous results of dispersion representations in the regions where some of the variables $p_i^2$ are in the physical Minkowski region, are reproduced by the Feynman-parameter representation for $F(p_1^2,p_2^2,p_3^2|m_1,m_2,m_3)$ through the extra replacements $p_i^2 \to p_i^2 + i0$ and $m_i^2 \to m_i^2 - i0$, where $m_i$ are masses of particles propagating in the loop. This implies that no deformation of the integration paths along the real axis of the Feynman parameters is forced by possible migrations of poles from the unphysical sheet to the physical one. The extra replacements allow us to take properly into account all subtle contributions given in the context of dispersion representations by the anomalous cuts and thresholds, and to provide the form factor on the upper boundaries of the cuts for all values of $p_i^2$.
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Chemical Physics
Molecular Insights into Gas Nanofilms Confined Between Bulk Liquid Phases
Yafan Yang, Zufeng Zuo, Xingyu Zhao et al. (+2 more)
Nanometer-thick fluid films play a critical role in confined multiphase processes, yet the thermodynamics and stability of free gas nanofilms remain poorly understood compared with their
liquid counterparts. Here, molecular dynamics (MD) simulations are employed to systematically investigate gas nanofilms confined between bulk
liquid phases using Lennard-Jones argon as a model system. The results show that the surface tension decreases exponentially with decreasing film thickness, accompanied by an increasing magnitude of the negative disjoining pressure. Upon thinning, the planar gas film undergoes a distinct morphological transition from a stable planar state to a transient or persistent spherical bubble through the formation and growth of a
liquid bridge. The film surface area strongly affects its thermodynamic properties, with larger areas producing stronger thickness dependence and larger deviations from classical density functional theory (cDFT) predictions. The closer agreement between MD and cDFT at smaller surface areas suggests that the discrepancy primarily arises from thermal capillary-wave fluctuations, which are included in MD but omitted in mean-field cDFT. Moreover, at small film thicknesses, the magnitude of the disjoining pressure increases with decreasing temperature, consistent with the enhanced sensitivity of the confined gas phase to thickness variations and contrasting with the trend generally reported for
liquid nanofilms. These findings provide molecular insights into the thermodynamics and stability of gas nanofilms, with implications for confined multiphase transport and droplet coalescence.
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All authors Yafan Yang, Zufeng Zuo, Xingyu Zhao, Shuyu Sun, Denvid Lau