High Energy Astrophysical Phenomena
Recurrent double-peaked $\gamma$-ray sub-flares in PKS 1424-418
Na Wang, Tong Liu and Jingran Xu
We report a hint of recurrent double-peaked $\gamma$-ray sub-
flares in PKS~1424–418 during two similar major active epochs, MJD 56117–56498 and MJD 59669–59978. The candidate double-peaked sub-
flares show a characteristic intra-subflare peak separation of $\sim 11.8$ d and a neighbouring-subflare spacing of $\sim 67$ d. Red-noise Monte Carlo tests indicate that the candidate recurrent double-peaked morphology is not easily reproduced by
stochastic variability alone, with false-alarm probabilities of $p_{\rm a}=0.0216$ and $p_{\rm b}=0.0006$ for the two active epochs, respectively. In the simulations of the entire
Fermi Large Area
Telescope (LAT) light curve, no red-noise realisation reproduces both epoch-like structures. The spectral energy distribution (SED) modelling shows similar radiative properties for the two peaks of one double-peaked candidate, while changes in the Doppler factor appear to play an important role in the flaring activity. Together with the previously reported near-zero lag between the millimetre and $\gamma$-ray emission, these results suggest that the recurrent activity may be associated with the compact mm/sub-mm core region. We discuss a possible structured-jet scenario in which a single disturbance propagates through a chain of quasi-stationary recollimation shocks. In this picture, repeated interactions between the disturbance and the shock structure may qualitatively account for both the double-peaked sub-
flare profiles and the observed $\sim 11.8$ d and $\sim 67$ d time-scales. Further active epochs are required to determine whether this similarity represents a recurrent long-term behaviour.
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General Relativity and Quantum Cosmology
Quasinormal modes of type II-perturbation for dilaton-Euler-Heisenberg black holes
Sheng-Yuan Li, Yun Soo Myung, De-Cheng Zou et al. (+1 more)
We study the quasinormal modes (QNMs) of Type II perturbations for dilaton-Euler-Heisenberg (dEH) black holes. These perturbations consist of coupled even-parity gravitational and dilaton perturbations together with odd-parity electromagnetic perturbations. The background is described by mass $M$,
magnetic charge $Q_m$, and dilaton coupling difference $\zeta=\alpha-\beta$ to the Euler-Heisenberg term. To find the QNM frequencies, we need to find the parameter space of $(\zeta, Q_m/M)$ that is free from vector ghosts. For the $\ell=1$ mode, the radiative block couples the dilaton and axial electromagnetic amplitudes, whereas the $\ell=2$ mode also contains metric amplitudes, so the frequencies are obtained from
matrix-valued boundary-value problems. We calculate QNM frequencies for the fundamental ($n=0$) branch with direct integration and the Chebyshev pseudospectral method, and compare the two computations wherever their charge intervals overlap. We find that the $\ell=1,2$ modes in the $n=0$ branch remain damped over the ghost-free parameter domain, supporting the stability of dEH black holes against Type II perturbations. The Type I sector will be presented elsewhere; no claim is made here about that sector, higher multipoles, or overtones.
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All authors Sheng-Yuan Li, Yun Soo Myung, De-Cheng Zou, Yu-Xuan Wang
Applied Physics
Teaching an LLM agent to fit XRR curves with X-Ray Calc 3
Oleksiy V. Penkov, Jingjing Peng and Haoyu Fu
The structure of a periodic multilayer X-ray mirror is obtained by fitting its X-ray reflectivity (XRR) curve, and the result depends on how the operator normalizes and trims the curve, frees parameters, and accepts a fit. The manual of the fitting program and the papers describing its engine leave these decisions to the operator, whose practice is tacit, so the fitting stays with the expert. To solve this problem, we proposed to develop a skill for a large
language model (LLM)
agent via elicitation: the expert's decisions were recorded during fitting and written as thirteen steps and a 22-item report template. The
agent runs X-Ray Calc 3 through a Model Context Protocol (MCP) tool server. Fresh sessions, each given the skill, one curve, and a nominal design, were scored against fits the expert had withheld, under six tolerances fixed beforehand. The skill was developed on XRR curves of Co/C mirrors and of Ru/C mirrors from a public data deposit. The final version of the skill was tested on W/B4C multilayers. It was demonstrated that the skill recovered the mean period within 0.3 Å of the expert's fits and the period drift through the stack on both W/B4C specimens, and the W and B4C thicknesses within 1 Å on one of them.
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Geophysics
SPBench: A Multi-Task Evaluation Benchmark for Exploration Seismic Processing
Qi Liu, Tianxiang Gao, Zhitong Cheng et al. (+4 more)
Exploration seismic processing underpins subsurface imaging and resource exploration, but learning-based methods remain difficult to compare across studies. Our survey of 368 papers finds widespread reliance on private or difficult-to-reproduce
datasets, with only 25 providing public code. This obscures whether reported gains arise from model design or experimental settings. We introduce the Seismic Processing
Benchmark (SPBench), covering six tasks: random noise attenuation, trace interpolation, ground-roll suppression, multiple suppression, deblending, and first-arrival picking. We reproduce 24 supervised methods on 10
datasets under 43 standardized settings and release
datasets, implementations, configurations, evaluation scripts, and results. To complement global scores and per-trace pick errors, we introduce signal-component-resolved evaluation (SCoRE) for reconstruction and a reference-free ridge-
curvature score (RC_norm) for first-arrival picking. Our analyses show that synthetic rankings do not reliably predict field rankings, with task-dependent agreement when models train within each setting. As degradation strengthens, rankings reorder more under coherent ground roll than under random-like interference. The ridge score agrees with MAE-based model rankings in the evaluated settings, with a mean Kendall correlation of 0.881 across three field surveys, while SCoRE reveals frequency- and energy-dependent differences hidden by global scores. SPBench provides a reproducible basis for comparing learning-based seismic processing methods and characterizes how their relative advantages vary across data settings, degradation strengths, and evaluation criteria.
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All authors Qi Liu, Tianxiang Gao, Zhitong Cheng, Chen Zhang, Peng Hu, Wei Gao, Jianwei Ma
Mesoscale and Nanoscale Physics
Zhi-Hai Liu, Jiang Zhang, Guilu Long et al. (+1 more)
Spin is typically traced out in the description of
quantum-dot-based Kitaev chains to simplify the construction of Majorana
fermions. Yet the intrinsic
spin structure of poor-man's Majorana modes in minimal Kitaev chains under finite Zeeman fields offers a natural interface for the Kitaev parity
qubit to interact with other spinful systems. Here, we establish such a platform to bridge the parity
qubit and a
quantum-dot
spin qubit, with the effective coupling governed by the
spin-dependent delocalization of the Majorana modes. Depending on whether the
spin qubit is coupled to one or two chains constituting the parity
qubit, the parity-
spin coupling exhibits distinct forms: an anisotropic parity-conserving exchange interaction or a nontrivial exchange tensor tunable via the interchain superconducting-phase bias. Leveraging fast
spin-
qubit manipulation, we further demonstrate universal parity-
qubit control, high-fidelity
qubit-state readout, and entangling operations between the parity and
spin qubits. These results turn the spinful structure of poor-man's Majoranas from a finite-field imperfection into a resource for hybrid
quantum control.
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All authors Zhi-Hai Liu, Jiang Zhang, Guilu Long, H. Q. Xu
General Relativity and Quantum Cosmology
Turning-Point Count Discrepancy as a Diagnostic of Relativistic Orbital Chaos
Wenfu Cao, Ying Wang and Hongsheng Zhang
We propose the turning-point count-discrepancy indicator (TPCD) for diagnosing orbital chaos from a single trajectory in relativistic
Hamiltonian systems with two oscillatory degrees of freedom. TPCD measures the largest cumulative departure of one turning-event count from its mean rate per reference cycle, requiring neither a neighboring orbit nor a phase-space partition and applying to both massive particles and
photons. We establish its long-time behavior under explicit event–phase assumptions. Rigid phases with an exact event–phase correspondence obey a strict discrepancy bound of unity, and linearizable regular
tori with bounded degree-one phase deformations obey a finite, orbit-dependent bound; both imply that the normalized indicator decays to zero as the record grows. A diffusive fluctuation mechanism instead yields a Brownian-bridge scaling and a finite statistical scale. Integrable Kerr motion validates the construction, recovering prescribed frequency ratios from event counts to within $2.6\times10^{-5}$ for six targets, including an irrational ratio. In charged-particle scans around a Kerr black hole in an external test
magnetic field, TPCD and the fast Lyapunov indicator agree for all 80 sampled trajectories. In the Schwarzschild–Melvin
photon model, a trajectory with elevated finite-time TPCD but low fast-Lyapunov values is identified as regular once its indicator trends downward over an extended integration, showing that finite-time values must be read together with their long-time trend.
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Quantum Gases
Moiré droplet of ultracold Bose gases in a twisted-bilayer optical lattice
Tianqi Luo, Jing Zhang and Xiaoling Cui
We report the emergence of Moiré droplet in two-dimensional ultracold
bosons subjected to a
spin-dependent optical
lattice, effctively realizing a twisted-
bilayer configuration. We show that the droplet formation dramatically enhances the visibility of Moiré pattern in the density profile, even for exceptionally weak
lattice potentials. The Moiré pattern can be enhanced similarly by increasing the
lattice depth, which, however, also induces droplet
diffusion characterized by a spreading density profile. Furthermore, we demonstrate a dynamical generation of Moiré pattern by dragging a small droplet through a moving
lattice. At appropriate velocities, the droplet undergoes bifurcation and exhibits pronounced Moiré pattern within periodic time intervals. Our results establish the ultracold droplet as a compelling platform for simulating interacting Moiré physics, particularly the interplay between Moiré
lattice and bound-state formation.
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Quantum Physics
Dense pentacene cocrystal demonstrates room-temperature coherent control
Noella D'Souza, Guangzhao Chen, Madhur Parashar et al. (+13 more)
Maximizing the number of addressable
spins within a fixed volume can improve ensemble
quantum sensor sensitivity, but dense packing usually increases dipolar interactions and excited-state transport, shortening coherence and suppressing optical readout. Here we report a 2:1 cocrystal of 6,13-dihydropentacene and pentacene (DHP/Pc) containing 33.3 mol% pentacene ($3.3\times10^{5}$ ppm; $9.51\times10^{20}$ cm$^{-3}$), a volumetric
spin-site density more than two orders of magnitude above previous
benchmarks, NV-diamond and pentacene-doped p-terphenyl (PDP). Despite this density, DHP/Pc exhibits microsecond
spin coherence, room-temperature optically detected
magnetic resonance and coherent control. Time-resolved measurements indicate that the long-lived triplet population is generated predominantly by intersystem crossing and exhibits strong, non-thermal sublevel polarization. Density-functional theory calculations further suggest that the native cocrystal geometry weakens electronic coupling between neighboring pentacenes, while the higher DHP triplet energy creates a barrier to triplet migration. These results identify molecular packing and coformer triplet energetics as complementary design parameters for preserving coherence in high
spin-site density systems, demonstrating cocrystallization as a promising route to dense, optically addressable
spin materials for room-temperature ensemble
quantum sensing.
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All authors Noella D'Souza, Guangzhao Chen, Madhur Parashar, Wern Ng, Brandon Wallace, Tatiana Lindahl, Tanner S. Volek, Lam Lam, Joseph Garrett, Emanuel Druga, Sean T. Roberts, Jeffrey Reimer, Harpreet Singh, Liang Z. Tan, Riccardo Montis, Ashok Ajoy
Mesoscale and Nanoscale Physics
Conductance of silicon nanotube junctions in high magnetic fields
Teresa Kulka, Juan Alberto Canché-Martín, Irina V. Lebedeva et al. (+2 more)
We investigate coherent
quantum transport through silicon nanotube (SiNT) junctions in high
magnetic fields up to 60 T using a tight-binding model combined with the non-
equilibrium Green's function formalism, and
magnetic field included via Peierls substitution. We consider junctions of metallic nanotubes (6,0)+(6,0) and semiconducting ones (9,9)+(9,9), and examine the effects of the overlap length, inter-tube distance,
magnetic-field direction, and field strength on the electronic transmission. In contrast to carbon nanotube junctions, the SiNT systems exhibit irregular transmission oscillations and do not show the emergence of highly conductive gateway states. The transmission is substantially more sensitive to a
magnetic field perpendicular to the nanotube axis than to a parallel field, while increasing the field strength progressively modifies the transmission spectrum. Increasing the overlap length results in more frequent transmission oscillations, whereas increasing the inter-tube distance modifies their positions and amplitudes without changing their overall character. Generally, similar trends are observed for both types of junctions, involving metallic and semiconducting nanotubes. However, in the junction of semiconducting nanotubes, one observes peculiar additional field-dependent in-gap transmission features. These results demonstrate that the
magnetic-field response of SiNT junctions is strongly governed by their geometry and differs qualitatively from that of pristine carbon nanotube junctions.
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All authors Teresa Kulka, Juan Alberto Canché-Martín, Irina V. Lebedeva, Jacek A. Majewski, Karolina Z. Milowska
Quantum Physics
Hochang Lee, Kyung Chul Jeong and Panjin Kim
A
quantum circuit for Gaussian elimination is developed in this work. While previous
quantum implementations of Gaussian elimination were restricted to $\mathrm{GF}(2)$, the proposed design is generalized to any finite field. Compared with previous works in $\mathrm{GF}(2)$, the developed
circuit achieves garbage-free construction while retaining the best known asymptotic Toffoli depth up to logarithmic factors.
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Instrumentation and Detectors
Characterization and Active Control of Position-Dependent Timing Dynamics in Superconducting Strip Single-Photon Detectors
Sahil R. Patel, Kristen M. Parzuchowski, Eli Mueller et al. (+6 more)
Superconducting strip single-
photon detectors (SSPDs) have emerged as scalable, wide-strip variants of traditional nanowire counterparts. Despite practical advantages including improved optical fill factors and enhanced signal-to-noise ratios the fundamental detection physics governing these micro-scale geometries remains largely unexplored. Here, we investigate the underlying photoresponse of a 20 um-wide tungsten silicide SSPD, demonstrating a slew-rate-corrected timing jitter of 13.2 ps at 532 nm and 20.5 ps at 1550 nm, alongside saturated internal detection efficiency up to 1550 nm. Using focused free-space optical scanning, we reveal that detector timing jitter is strongly influenced by a spatially dependent slew rate between edge and center absorption events. To mitigate this impact, we utilize a parallel superconducting rail architecture to actively redistribute supercurrent. This in-situ tuning minimizes the latency mismatch and mitigates thermally activated intrinsic dark counts, extending the device's ability to operate at higher temperatures. Finally, comparing these dynamics with time-dependent Ginzburg-Landau (TDGL) modeling elucidates the physical origins of the position-dependent photoresponse, highlighting how superconducting rails or specialized readout electronics can mitigate negative impacts on timing jitter.
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All authors Sahil R. Patel, Kristen M. Parzuchowski, Eli Mueller, Boris Korzh, Emanuel Knehr, Adam N. McCaughan, Martin J. Stevens, Matthew D. Shaw, Jason P. Allmaras
Materials Science
Influence of chemical vapor deposition conditions on N incorporation ratio on vicinal 4H-SiC(000-1) surface: Ab Initio-based approach
Wataru Ota, Akira Kusaba, Yoshihiro Kangawa et al. (+3 more)
In experimental studies, increasing the ratio of source gases (C3H8/SiH4; C/Si ratio) for chemical vapor deposition (CVD) causes the growth rate to increase monotonically, and nitrogen incorporation tends to decrease accordingly; however, a unique phenomenon has been observed in which nitrogen incorporation increases discontinuously in the range of C/Si ratio between 1.0 and 1.5. This phenomenon is specific to the vicinal 4H-SiC(000-1) C-face and is not observed on the vicinal 4H-SiC(0001) Si-face. In this study, N incorporation behavior on a vicinal C-face during CVD is investigated using an ab initio-based approach. The calculation results suggest that when C/Si ratio is less than 1.0, the Si-terminated step edge is stable, whereas when C/Si ratio exceeds 1.0, the existence probability of the C-H-terminated step edge, where the N substitution energy is lower than in the former case, increases sharply. This change in the step-edge state across C/Si = 1.0 is thought to be the cause of the discontinuous increase in N incorporation.
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All authors Wataru Ota, Akira Kusaba, Yoshihiro Kangawa, Keisuke Kurashima, Ichiro Mizushima, Kenji Shiraishi
Solar and Stellar Astrophysics
Study of Chromospheric Global-Scale Flows using Local Correlation Tracking Across the past 10 Solar Cycles
Qin Li, Yan Xu, Keiji Hayashi et al. (+2 more)
Global-scale
solar surface flows, including differential rotation and meridional circulation, provide key observational constraints on the
solar dynamo. We investigate these flows using local correlation tracking (LCT) of chromospheric intensity structures in digitized \ion{Ca}{2}~K observations from the Kodaikanal
Solar Observatory covering
Solar Cycles (SC) 14 to 23 (1907 – 2007). The most valuable data coverage are from cycles 14 to 19 for two reasons: (1) it provided record for early cycles that are not commonly available; (2) it had much better duty cycle than the data of cycles 20-23, therefore the measurements had much less errors. On the other hand, the information loss in cycles 20-23 are compensated by other modern space observations. The recovered differential rotation shows relatively small cycle-to-cycle variations and remains close to the Howard reference profile. Recurring zonal-flow residual bands at low and middle latitudes are broadly associated with the activity belts during the well-sampled SC~15–19. The meridional flow is predominantly poleward in the earlier record and exhibits larger relative cycle-to-cycle variations and uncertainties. Incomplete coverage of SC~14 and sparse sampling during SC~21–23 limit detailed comparisons to the better-covered SC~15–20. Compared with its immediate successor SC~19, the strongest cycle in the record, SC~18 exhibits a stronger and continuous northern poleward meridional branch, peaking two to three years before its sunspot maximum. SC~19 shows a minor enhancement that peaks earlier prior to its own maximum. An independent comparison using PSPT observations yields a full-period correlation of $r=0.91$ between the LCT and SDO/HMI meridional-flow profiles. These results extend the observational context for
solar-cycle-related flows over a century and motivate further refinement through data-driven reconstruction.
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All authors Qin Li, Yan Xu, Keiji Hayashi, Chunlei Liang, Haimin Wang
Solar and Stellar Astrophysics
Central stars of newly discovered infrared nebulae: eruptive Be stars PY Gem and HD253659
Olga Maryeva, Julieta Sánchez Arias, Sergey Karpov et al. (+3 more)
The presence of a nebula around massive hot
stars often works as an indicator that the object is either in an advanced evolutionary stage or a rare product of close binary interaction. Here, we focus on two Be
stars - PY Gem and HD253659 - whose nebulae were detected with the Wide-field Infrared Survey Explorer. We estimated their basic physical parameters from modelling the spectral energy distribution and examined their variability. We combined archival photometric data from several ground-based survey
telescopes and from the Transiting
Exoplanet Survey Satellite (TESS) with our own data from dedicated multi-colour photometric and spectroscopic monitoring, and concluded that, despite having similar
stellar properties, the photometric variability of the two objects is strikingly different. For HD253659 we detected continuous eruptive variability and a major outburst that took place between 2016 and 2022 along with numerous flicker events seen in the TESS data. HD253659 also exhibits loop-like behaviour in the colour-magnitude diagram, consistent with build-up and dissipation phases of a circumstellar disk seen close to pole-on. In contrast, during the past ~20 years PY Gem has lost its eruptive variability and shows only small-amplitude p and g-mode pulsations classifying PY Gem as \beta Cephei hybrid pulsator. An incoherent low-frequency signal is identified as a Štefl frequency, which seems to be supported by the cyclic variation of the emission-line profiles. Detailed analysis of these
stars indicates that both objects are inconsistent with evolved massive
stars, and that the origin of their nebulae is more likely linked to the physics of the Be phenomenon.
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All authors Olga Maryeva, Julieta Sánchez Arias, Sergey Karpov, Michaela Kraus, Michalis Kourniotis, Sabina Mammadova
Quantum Physics
Learned-projector QAOA for hierarchical optimization
Kangyun Zhou, Dong An and Jin-Peng Liu
Many optimization problems reveal inexpensive structural information before requiring costly final evaluation, whereas the conventional
quantum approximate optimization
algorithm (QAOA) applies a single aggregate objective throughout. We introduce the learned-projector
quantum alternating operator ansatz (LP-QAOA), a multistage protocol that freezes optimized
circuits and uses their output states to define later projector mixers. We prove a stability
theorem for LP-QAOA that bounds the propagation of approximation errors through successive frozen stages. Our analysis also shows how learned-projector mixing avoids the high-order tunnelling suppression of local mixers. We conduct state-vector simulations on block-constrained
spin tiling (BCST) instances, where LP-QAOA achieves higher probabilities of sampling the optimum, lower estimated logical-resource requirements, and better trainability than the tested baselines. A supporting
stochastic block model experiment extends LP-QAOA to optimization problems with soft hierarchical structure. Our results highlight the potential of LP-QAOA to improve variational
quantum optimization by exploiting hierarchical problem structure.
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Fluid Dynamics
Global modal/non-modal analysis of high-enthalpy Martian entry vehicles
Adrián Antón-Álvarez and Adrián Lozano-Durán
We analyze laminar-to-turbulent transition over a blunt capsule representative of Martian entry at Mach 26 using global modal and transient-growth analyses about a thermochemical base flow characteristic of high-altitude entry conditions. Across the Reynolds-number range considered ($Re_\infty = 10^4$–$10^6$), the axisymmetric global eigenspectrum remains stable, ruling out temporally unstable axisymmetric global modes as a viable route to transition. The flow nevertheless supports strong transient growth concentrated in the shear–
entropy layer generated by bow-shock
curvature. Energy-budget analysis reveals a two-stage process: Reynolds-stress production in the mean shear first amplifies kinetic disturbances, which then generate
entropy fluctuations as they traverse the strong base-flow
entropy gradient. The optimal gain scales linearly with the Reynolds number based on the capsule nose radius, whereas boundary-layer-localized disturbances become competitive at the highest Reynolds numbers examined. These results identify shear–
entropy-layer transient growth as a plausible linear pathway for seeding transition in high-enthalpy blunt-entry vehicles.
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Fluid Dynamics
Wave-driven propulsion of a flexible raft
Elvis A. Agüero and Daniel M. Harris
Inertial propulsion in fluids generally arises from an unbalanced flux of momentum. For the case of wave-driven propulsion, momentum is transported away from an oscillating raft in the form of self-excited surface waves. While this mechanism has previously been analyzed for rigid rafts, the role of flexibility has yet to be investigated. In this work, we develop a fluid-structure interaction model for a periodically driven two-dimensional flexible raft resting at the free surface of a fluid. The raft is modeled as an Euler–Bernoulli beam and is coupled to a weakly dissipative quasi-potential model of the fluid beneath. Varying the flexural stiffness and forcing position reveals new features associated with the introduction of flexibility, including the possibilities of thrust enhancement and reversal. By projecting the raft response onto its free rigid-body and elastic modes, the fluid loading can be represented as a modal impedance, informing a computationally efficient reduced-order model. Analysis of the modal response and its
symmetries facilitates physical interpretation of our key findings. For a uniform raft, excitation of any single mode in isolation is incapable of producing a net thrust, and thus efficient wave propulsion requires a blend of interfering modes with appropriately coordinated amplitudes and phases.
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Quantum Physics
Efficient Record-and-Replay Arithmetic for Quantum Elliptic-Curve Point Addition
Jieyi Long, Theodore Pender, Zhao Huang et al. (+33 more)
We study reversible secp256k1 point-addition
circuits developed through ECDSA.Fail for Shor's
elliptic-curve discrete-logarithm
algorithm. Two complementary constructions improve record-and-replay GCD arithmetic: Jump-2 groups binary-GCD steps and compresses their decisions using base-5 encoding, while ping-pong uses fixed register alternation and one-bit decisions to avoid full-width comparisons and data-dependent swaps. Fused replay combines doubling and signed addition into one modular correction. Both constructions support
quantum-addressed window selection with measurement-based lookup cleanup. We compare three
circuits on 100,000 fresh inputs across nine lookup-table configurations. A separately tested repair uses 1,419
qubits and 1.356 million mean executed Toffolis, with no detected failures on another 100,000 inputs. Structured supported-input counterexamples remain, so these tests do not establish all-input correctness. We also provide conditional coherent-error analysis and reversible safegcd comparisons. Under the stated window allowance, repaired-
circuit resources lie below Google's low-gate caps and Schrottenloher's low-gate estimates, but differing accounting and correctness evidence preclude formal dominance. The results concern individual window-selected additions, not complete Shor computations.
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All authors Jieyi Long, Theodore Pender, Zhao Huang, Manuel B. Santos, Samrendra Kumar Singh, Bartosz Naskręcki, BitWonka, Pierre-Luc Dallaire-Demers, Francesco Giannicola, Ruben M. L. Paschoarelli, Oli Freuler, Jackie Chia-Hsun Lee, Vasily Gnuchev, Gopi Kannappan, John Boyer, Xavier Butler, Akash Balasubramani, Jordan Newman, Bereket Dereje, Alexander Hertlein, Robert Kodra, Lucas Levy, Shaan Patel, JT Rose, Matt Zweil, Okechukwu Wisdom, Tarek El-Eter, Edison Lee, Michael Dong, Alan Li, Anto Joseph, Duy Nguyen, Gajesh Naik, Gautham Anant, Soubhik Deb, Justin Drake
Quantum Physics
Reconfigurable Bus-based Quantum Router for Modular Superconducting Processors
Benzheng Yuan, chaojie Zhang, Yangyang Fei et al. (+7 more)
Scaling superconducting
quantum processors requires interconnects that provide both non-local connectivity and parallel entangling operations. While current
quantum routers offer greater connectivity than nearest-neighbour
topologies, their support for parallel, independently addressable two-
qubit gates remains fundamentally limited, imposing severe compilation overheads that constitute a critical bottleneck. Here we introduce a bus-based reconfigurable
quantum router that enables parallel controlled-$Z$ (CZ) gates for modular superconducting processors. Constructed from a flux-tunable SQUID network, the router selectively connects interface
qubits to two shared buses, allowing destructive interference to suppress idle interactions while supporting two disjoint CZ gates in parallel. Full-system
Hamiltonian simulations yield parallel-gate infidelities ranging from $7.9\times10^{-4}$ to $1.8\times10^{-3}$ under the operating conditions considered, and an open-system analysis identifies the coherence requirements for high-fidelity operation. We further assess the
circuit-level consequences using hardware-aware compilation and resource-constrained scheduling. For the 36-
qubit quantum Fourier transform (QFT), QAOA-MaxCut, and random-pairing
circuits, the router reduces the median SWAP count by up to $34\%$ and the native CZ count by up to $20\%$ relative to a matched two-dimensional grid.
Circuit-depth reductions are workload-dependent, reaching $20\%$ for QAOA-MaxCut but remaining negligible for the QFT despite its lower gate count. These results show that enhanced connectivity and schedulable parallelism provide complementary benefits for connectivity-intensive
algorithms, establishing the router as a compiler-visible hardware resource and providing a scalable architectural pathway toward constructing highly connected modular superconducting
quantum processors.
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All authors Benzheng Yuan, chaojie Zhang, Yangyang Fei, Chuanbing Han, Haoran He, Huihui Sun, Bo Zhao, Fudong Liu, Weilong Wang, Zheng Shan
Chemical Physics
Validating Spectral Quality Measures as Proxies for Task Performance: A Controlled-Perturbation Framework for Raman Spectroscopy
Xiuyi Qin
Raman preprocessing and enhancement methods are often assessed by comparing their output with a clean reference spectrum using measures such as mean squared error (MSE). Whether these spectral quality measures reflect downstream analytical performance is rarely tested. We propose a controlled-perturbation framework for this test. Five perturbation types (baseline distortion, independent noise, correlated noise, global wavenumber shift, and nonlinear axis warping) at eight strengths produce paired changes in a quality measure (metric harm) and in downstream performance (task harm). The
alignment gap (AG) quantifies how much a single monotone metric-to-task relationship, fitted by isotonic regression, improves when each perturbation type receives its own relationship. Ordering concordance (OC), a clustered Kendall-type index, measures how often a measure ranks conditions of different perturbation types in the same order as their task harm. Cluster-bootstrap intervals and Holm-adjusted sign-flip tests compare twelve candidate measures with MSE. Three public
datasets are used: bacterial classification by principal component analysis and logistic regression, sugar-mixture quantification by partial least squares regression, and mineral identification by cosine library matching. Models are fitted to unperturbed or to correspondingly perturbed training spectra. For bacterial classifiers fitted to unperturbed spectra, Wasserstein distance improved both statistics relative to MSE (Holm-adjusted p < 0.05), also after axis perturbations were removed or spectra were compared on a common grid; refitting to perturbed spectra reversed this advantage. Peak-based measures and a structure-to-noise ratio improved both statistics only for refitted sugar calibrations, and no candidate did so for mineral identification. Open code supports testing new measures.
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Instrumentation and Methods for Astrophysics · Cross-listed from cs.LG
Image Fidelity is Not Field Fidelity: Joint Thermodynamic Reconstruction and Error Localization in Neural Tomography
Alan Hsu, Jenna Samra, Alin Razvan Paraschiv et al. (+1 more)
Neural fields for scientific
tomography are optimized from 2D images, but the actual quantity of interest is often a latent 3D physical field. Because the forward map is many-to-one, low 2D image error need not certify a correct 3D field. Moreover, the latent field is not directly supervised during training, and its error cannot be evaluated against truth at deployment. We develop CoroNeRF to jointly optimize 3D electron density and temperature fields directly from multiview, multiline intensities through a differentiable atomic-emission renderer. Using
solar coronal
tomography as a controlled testbed, we evaluate physical-field recovery and test whether cross-seed instability provides a ground-truth-free-at-inference indicator of local physical-field error. We underscore the following two observations. (i) Image fidelity is not field fidelity: spectral ablations show that limited-channel reconstructions can fit their available observations well while recovering substantially worse fields, whereas evaluation on a common richer probe exposes the discrepancy. (ii) Cross-seed instability ranks local physical-field error across tested matched-model conditions, supported by sparsification and physical signal-strength controls. Seed-deviation projections provide complementary directional validation, but shared forward-model mismatch can still produce incorrect cross-seed consensus. These results characterize joint thermodynamic recovery and the usefulness and limits of seed-based error localization in a controlled, single-scene
solar tomography testbed.
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All authors Alan Hsu, Jenna Samra, Alin Razvan Paraschiv, Liam Connor
Materials Science
Magnetostrictive properties in Fe$_{4-x}$Co$_{x}$N films: Insight from experiments and first-principles calculations
Huameng Yu, Keita Ito, Shoya Sakamoto et al. (+4 more)
The
ferromagnetic nitride Fe$_{4}$N has attracted
attention for application in spintronic devices due to its high
spin polarization and large magnetostriction. We present a combined experimental and theoretical study on the magnetostriction of Fe$_{4-x}$Co$_{x}$N films across a wide composition range. The Fe$_{4-x}$Co$_{x}$N films were grown on SrTiO$_{3}$(001) substrates using molecular beam epitaxy, and the magnetostriction constants along the [100] direction (${\lambda}$$_{100}$) and [111] direction (${\lambda}$$_{111}$) were precisely evaluated using an optical cantilever method. The experimental results reveal that ${\lambda}$$_{111}$ remains positive in the whole composition range and shows a maximum value of +82 ppm around x = 0.9. The variation in ${\lambda}$$_{111}$ with x is much smaller than that in ${\lambda}$$_{100}$, for which
giant tunability and sign reversal are observed. First-principles calculations show reasonable agreement with the experimental ${\lambda}$$_{111}$ for x ${\ge}$ 1.6, but give negative values at lower x, and an exceptionally large negative ${\lambda}$$_{111}$ is obtained at x = 0.8, where the
Fermi level coincides with a pronounced minority-
spin peak in the density of states. The calculated ${\lambda}$$_{111}$ depends strongly on the smearing parameter, indicating that the rhombohedral magnetostriction is highly sensitive to the treatment of atomic disorder. The saturation magnetostriction constant (${\lambda}$$_{s}$) derived from ${\lambda}$$_{100}$ and ${\lambda}$$_{111}$ is also compared with the ${\lambda}$$_{s}$ measured for the (001)-oriented polycrystalline Fe$_{4-x}$Co$_{x}$N films, and a possible scenario for deviation between them is discussed. Our findings clarify the basic features of magnetostriction in the Fe$_{4-x}$Co$_{x}$N system, providing essential magnetoelastic parameters for designing nitride-based spintronic devices.
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All authors Huameng Yu, Keita Ito, Shoya Sakamoto, Ivan Kurniawan, Yoshio Miura, Yasushi Endo, Takeshi Seki
Nuclear Theory
Electromagnetic properties in $^{160-170}$Dy nuclei: A microscopic description by the pseudo-SU(3) shell model
Carlos E. Vargas, Víctor Velázquez, Sergio Lerma-Hernández et al. (+1 more)
The large collectivity observed in the rare earth region of the
nuclear landscape is well known. The microscopic studies are difficult to perform in this region due to the enormous size of the valence spaces, a problem that can be avoided by means of the use of
symmetry based models. Here we present calculations for electromagnetic properties of $^{160-170}$Dy
nuclei within the pseudo-SU(3) scheme. The model
Hamiltonian includes the preserving
symmetry $Q\cdot Q$ term and the
symmetry-breaking Nilsson and pairing terms, systematically parametrized for all members of the chain. The model is used to calculate B(E2) and B(M1) inter-band transition strengths between the ground state, $\gamma$ and $\beta$-bands. In addition, we present results for quadrupole moments and $g$ factors in these rotational bands. The results show that the pseudo-SU(3) shell model is a powerful microscopic theory for a description of electromagnetic properties of states in the normal parity sector in heavy deformed
nuclei.
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All authors Carlos E. Vargas, Víctor Velázquez, Sergio Lerma-Hernández, Norma Bagatella-Flores