Quantum Physics
Optimal low-rank compression of quantum dynamics
Hugo Mackay, Donghoon Kim, Tan Van Vu et al. (+1 more)
Local
quantum interactions generate dynamics in an exponentially large
Hilbert space, yet locality and
entanglement restrict the information that can spread and accumulate. Bounds on propagation and
entanglement growth, together with tensor networks, exploit these restrictions to discard information unnecessary for describing the
evolution. This leads to a sharper question: how much information must any low-rank representation retain? Here we determine these limits, up to logarithmic factors, for short-range interactions. For time-independent
evolution, the optimal rank obeys $\log D=\widetilde O(t+\sqrt{\log(1/\epsilon)})$, with matching lower bounds fixing the accuracy exponent $1/2$; for arbitrary driving, matching fixed-time bounds instead give $2/3$. Correspondingly, the corresponding dynamical
entanglement spectra exhibit distinct small-$\alpha$ Rényi laws, $\alpha^{-1}$ and $\alpha^{-2}$. In one dimension, the static limit is constructively attained by an explicit MPO
algorithm, with an analogous extension to Liouvillian dynamics. Together, these results determine the irreducible information required to represent local
quantum evolution and uncover distinct
entanglement structures in static and driven dynamics.
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All authors Hugo Mackay, Donghoon Kim, Tan Van Vu, Tomotaka Kuwahara
High Energy Astrophysical Phenomena
Origin of the high-energy spectral cutoff in gamma-ray pulsar halos
Qi-Ling Chen, Ming-Ming Kang, Kun Fang et al. (+2 more)
The spectra of gamma-ray
pulsar halos exhibit a clear cutoff feature at tens of TeV. This work investigates the origin of the spectral cutoff by interpreting the HAWC data of the Geminga
halo. The most straightforward interpretation is that the cutoff reflects the maximum electron acceleration capability of the central PWN. We model this scenario using spherically symmetric diffusive shock acceleration, where the upstream scale of the PWN termination shock limits the maximum energy. We also propose an alternative interpretation of the cutoff: if the electron
diffusion coefficient in the surrounding interstellar medium rises rapidly at high energies, a substantial fraction of high-energy gamma-ray flux from the target source can leak outside the analysis region, producing an observed spectral cutoff effect. Both explanations successfully reproduce the spectral cutoff of the Geminga
halo. Meanwhile, the two scenarios make distinct predictions on the statistical properties of
pulsar halo spectral cutoffs and the X-ray spectral features of the corresponding PWNe, which may be tested through further observations.
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All authors Qi-Ling Chen, Ming-Ming Kang, Kun Fang, Yi-Qing Guo, Chao-Wen Yang
High Energy Astrophysical Phenomena
On the rates of binary star collisions around hypermassive black holes
Megha Sharma, Alexander Heger, Evgeni Grishin et al. (+1 more)
Observations of the Milky Way show that
galaxies have binary
stars in their centres. Using Monte Carlo simulations, we model the population statistics of encounters of such binaries with
galactic central black holes (BHs) of mass 10^5-10^{10} Msun (hypermassive BHs >= 10^8 Msun HMBHs). Whereas main-sequence single
stars cannot undergo
tidal disruption events around HMBHs,
stellar collisions of main-sequence binary
stars may produce observable transients. We use the post-Newtonian Einstein-Infeld-Hoffmann (EIH) equations as implemented in the three-body code Multistar. We simulate 100,000 models each for six BH masses and 10 different binary parameter distributions. We find that
stellar collisions occur in all models, with collision fractions ranging from ~7% for circular, equal-mass binaries to ~0.2% for the observationally motivated Moe2017 binary distribution. Most collisions occur for prograde, tight binaries at low impact parameters beta = r_t/r_p, where the
tidal force of the BH drives up the binary eccentricity during pericentre passage. Collision velocities are close to the binary escape velocity for lower-mass BHs (<= 10^8 Msun), but span a wider range for higher-mass BHs, implying an increasing fraction of
stellar mergers. Using empirical loss-cone rates and the local BH mass function, we estimate detectable LSST collision rates of ~8,600 and ~3,000 events per year for our Kroupa mass function, Opik's law, inclined orbit model and our MS17 model, respectively, around 10^6 Msun BHs; ~330 and ~150 events per year around 10^8 Msun BHs; and ~3.5 and ~2.8 events per year around 10^9 Msun BHs. These results suggest that binary
stellar collisions around HMBHs represent a potentially observable population of
nuclear transients that may contribute to the growing sample of ambiguous
nuclear transients detected by wide-field optical surveys.
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All authors Megha Sharma, Alexander Heger, Evgeni Grishin, Daniel J. Price
Quantum Physics
On Relationship Between Circuit Depth and Trainability of VQAs
Jan Michálek, Martin Friák and Petr Vašík
The training efficiency of Variational
Quantum Algorithms (VQAs) is dictated by the geometry of their loss landscapes, which can be formally analysed by mapping these functions to random fields on
manifolds. Instead of VQAs, we can then directly study the corresponding random fields, in our case, the Wishart Hypertoroidal Random Fields (WHRFs). We are mostly interested in the distribution of critical points (especially local minima) of WHRFs. For this purpose, the Kac-Rice formula is presented, reformulated, and simulated. The findings identify a phase transition in the distribution of local minima. Beyond a specific threshold, local minima concentrate near the global minimum in function value, meaning that even local minima are good approximators of the global one. The threshold is governed by the ratio between the problem
Hamiltonian degrees of freedom and by the number of independent parameters in the VQA. Since the degrees of freedom parameter scales exponentially, we propose
symmetry reduction operations to lower the degrees of freedom. This mathematically reduces the dimension, scaling down the required parameter threshold and enabling to solve bigger problems.
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Materials Science
Spurious spin nutation modes arising from truncated memory effects
Markus Weißenhofer, Ritwik Mondal, M. S. Mrudul et al. (+1 more)
Spin dynamics is conventionally treated as inertia-free. The inertial Landau-Lifshitz-Gilbert equation (iLLG) extends this with a second-order time derivative, predicting a high-frequency nutational mode that recent experiments have claimed to observe and interpreted as direct evidence for
spin inertia. We show that when
spin inertia is generated by eliminating additional dynamical degrees of freedom, the resulting exact
spin-only description is generally non-Markovian. The iLLG is recovered as the low-frequency, second-order truncation of the underlying
memory kernel. Using a minimal
spin–cavity model, we show that the exact eigenfrequencies and those obtained via the iLLG differ and that the
spin nutation mode predicted by the latter is a truncation-induced high-frequency artifact. This raises a broader question of the applicability of the iLLG obtained from analogous low-frequency truncations, which may likewise generate spurious high-frequency roots. Consequently, agreement of a high-frequency spectral feature with the iLLG nutation frequency does not, by itself, establish a physical nutation mode.
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All authors Markus Weißenhofer, Ritwik Mondal, M. S. Mrudul, Peter M. Oppeneer
Earth and Planetary Astrophysics
Kelvin-Helmholtz vortices in the Martian +E hemisphere downstream of crustal magnetic anomalies
Junxi Niu, Tong Dang, Jiuhou Lei et al. (+6 more)
At unmagnetized planetary bodies, the Kelvin-Helmholtz (KH) instability at the
solar-wind boundary is a key driver of atmospheric escape, fundamentally shaping long-term
climate evolution. This shear-driven
plasma mixing is theoretically predicted to be asymmetric, strongly favoring the hemisphere where the
solar-wind electric field points toward the
planet (-E hemisphere). Here we report the observation of a coherent train of fully developed KH
vortices in the traditionally unfavorable +E hemisphere of Mars, using in-situ MAVEN measurements. Contemporaneous upstream constraints from Tianwen-1 confirm a steady interplanetary
magnetic field, indicating sustained shear-driven growth rather than a transient boundary response. We find that these
vortices developed within an expanded, weak-field boundary layer downstream of strong southern crustal
magnetic anomalies. Our analysis suggests that regional boundary structuring can override the large-scale hemispheric preference to facilitate localized KH growth. These findings demonstrate that shear-driven escape pathways can operate in traditionally unfavorable regions, altering our understanding of atmospheric volatile loss at weakly magnetized
planets.
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All authors Junxi Niu, Tong Dang, Jiuhou Lei, Binzheng Zhang, Wenya Li, Binbin Tang, Junjie Chen, Sudong Xiao, Tielong Zhang
High Energy Physics (Phenomenology)
The semileptonic decays of $\Omega_{b}^{*}$, $\Sigma_{b}^{*}$ and $\Xi_{b}^{\prime*}$ baryons
Peng Yang, Guo-Liang Yu, Zhi-Gang Wang et al. (+2 more)
In this article, we employ the QCD sum rules basing on three-point correlation function to systematically analyze the transition form factors for the semileptonic decays of the
spin \(\frac{3}{2}^{+}\) bottom
baryons (\(\Omega_{b}^{*}\), \(\Sigma_{b}^{*}\), and \(\Xi_{b}^{\prime *}\)) to their corresponding
spin \(\frac{1}{2}^{+}\) charmed partners. On the phenomenological side, we eliminate the contaminations of the
baryons with negative parity and those with lower
spin states. The operator product expansion is carried out up to dimension-six condensates, including the perturbative part,
quark condensate \(\langle \bar{q} q\rangle\),
gluon condensate \(\langle g_{s}^{2}GG\rangle\), mixed condensate \(\langle \bar{q} g_{s}\sigma Gq\rangle\), and four-
quark condensates \(\langle \bar{q} q\rangle^{2}\) and \(g_{s}^{2}\langle \bar{q} q\rangle^{2}\). The form factors are evaluated in the space-like region and then are fitted into the time-like physical region via a $z$-series expansion approach. Finally, the semileptonic decay widths for $\Omega_{b}^{*}$, $\Sigma_{b}^{*}$ and $\Xi_{b}^{\prime*}$
baryons are calculated with our predicted form factors, and various polarization observables are also predicted. The predicted results in this work are compared with those predicted by other collaborations, and are expected to be useful for studying the properties of these singly heavy
baryons.
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All authors Peng Yang, Guo-Liang Yu, Zhi-Gang Wang, Jie Lu, Bin Wu
High Energy Physics (Phenomenology)
Dynamical gluon effects in proton transversity and off-forward parton distributions from a light-front Hamiltonian approach
Pengxiang Zhang, Jiangshan Lan, Siqi Xu et al. (+3 more)
Building on
proton light-front wave functions in the $|qqq\rangle$ and $|qqqg\rangle$ Fock sectors, obtained by diagonalizing the
proton light-front
Hamiltonian within the Basis Light-Front Quantization framework, we present a unified study of the
proton's leading-twist transversity parton distribution functions, tensor charges, generalized tensor form factors, and
chiral-odd skewed generalized parton distributions in the Dokshitzer-Gribov-Lipatov-Altarelli-Parisi region. Our results compare reasonably with available phenomenological extractions and
lattice-QCD simulations and follow similar qualitative trends.
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All authors Pengxiang Zhang, Jiangshan Lan, Siqi Xu, Chandan Mondal, Xingbo Zhao, James P. Vary
Materials Science
Investigation of Hopping Conduction and Its Impact on the Subthreshold and Transition Region Transport in Oxide Semiconductor Transistors by Magneto-Transport Measurements
Chen Wang, Liankai Zheng, Kai Jiang et al. (+4 more)
In this work, magneto-transport measurements, including
Hall effects and magnetoresistance (MR) at various temperatures, are employed to directly probe the electron transport properties in crystalline indium
oxide (In2O3) and amorphous indium-zinc
oxide (IZO) transistors. For the first time, we develop a subgap density of states (DOS) extraction method based on the MR measurements at low temperature, considering both the interference and orbital shrinkage effects. The sign and magnitude of MR are used as direct evidence to distinguish the dominating transport mechanisms between hopping conduction and free-electron conduction. It is found that crystalline In2O3 exhibits a subgap DOS more than two orders of magnitude lower than that of amorphous IZO, together with a smaller localization radius of hopping sites. As a result, crystalline In2O3 not only enhances the carrier mobility but also significantly reduces the supply voltage (VDD) because of the smaller transition region enabled by the much-suppressed subgap DOS. This study reveals that structural disorder critically influences the device operation in the subthreshold and transition regions of
oxide semiconductor transistors.
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All authors Chen Wang, Liankai Zheng, Kai Jiang, Jinxiu Zhao, Zhenyu Zhang, Xuefei Li, Mengwei Si
Astrophysics of Galaxies
Ubiquitous nuclear disks and bars embedded in massive galaxies in the cosmic morning
Jianyuan Luo, Fangzhou Jiang, Jinning Liang et al. (+8 more)
The morphology of the central regions of high-
redshift galaxies remains relatively unexplored, while recent case studies suggest that
giant disks can emerge without first developing a prominent central spheroid. Here, we investigate the inner structures of a mass-complete sample of 45 massive
galaxies at $z=3$ in the TNG50 simulation. Through double-Sérsic profile decomposition, isodensity ellipse fitting, intrinsic three-dimensional shape measurements, and
stellar kinematics, we find that these central structures are ubiquitously flattened and rotation-supported with low Sérsic indices ($n \lesssim 1$). This indicates that the central regions are predominantly
nuclear disks and bars rather than bulges. Tracking their
evolution, we show that these
nuclear disks and bars emerge during gas-rich compaction and do not transform into spheroidal and dispersion-dominated systems until $z \lesssim 1$, before which extended
stellar disks have already developed. Our results suggest that massive disks can assemble around rotation-supported centers and bulge-deficient massive
galaxies may be a common outcome of
galaxy evolution.
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All authors Jianyuan Luo, Fangzhou Jiang, Jinning Liang, Boris S. Kalita, Pinsong Zhao, Jinyi Shangguan, Bingcheng Jin, Zeyu Gao, Weichen Wang, Luis C. Ho, Yingjie Peng
Quantum Physics
Precision and resource scaling of real-time flux distortion compensation for superconducting quantum control
Qi Zhou, Zi-Hao Mei, Peng Duan et al. (+7 more)
Real-time waveform generation supports dynamic
quantum circuits without pre-storing complete waveforms for every execution path. However, long-lived distortions in flux-control lines degrade gate fidelity, requiring compensation to account for the actual pulse history. A frequency-domain inversion and time-domain fitting method is proposed for resource-efficient real-time flux distortion compensation. The method fits the reconstructed compensation impulse response with a compact hybrid infinite impulse response (IIR) and finite impulse response (FIR) filter. Look-ahead parallelization enables this filter to process synthesized waveforms at 1.2GSa/s on a field-programmable gate array (FPGA). Two-
qubit cross-
entropy benchmarking shows that real-time IIR filtering achieves a median controlled-Z Pauli fidelity close to the software-reference value of 99.57%. Numerical analysis and FPGA synthesis indicate approximately logarithmic growth in hardware resource use with compensation timescale. Extending compensation from microsecond to hundred-microsecond timescales increases look-up table (LUT) and digital signal processing (DSP) resource use by only about 14% and 4%, respectively, while maintaining a relative arithmetic error below $10^{-4}$. This work provides a scalable hardware foundation for high-fidelity flux control in dynamic superconducting
quantum circuits.
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All authors Qi Zhou, Zi-Hao Mei, Peng Duan, Peng Wang, Liang-Liang Guo, Hao-Ran Tao, Wei-Cheng Kong, Hui Yang, Guo-Ping Guo, Zhao-Yun Chen
General Relativity and Quantum Cosmology
Conserved charges and the first law of black holes for field dependent symmetry generators in the covariant phase space formalism
Hai-Feng Ding
In this paper, we generalize the covariant phase space formalism conjugate to field dependent vectors to include internal gauge transformations when gauge fields are present. In our formalism, the
symmetry generators are combination of diffeomorphisms plus internal gauge transformations and depend on the field configuration. When the field dependence of the
symmetry generators is considered in the covariant phase space formalism, the first law of black hole thermodynamics is a direct result for generally invariant gravitational theories. To check the validity of our formalism, we investigate the conserved charges and the first laws of thermodynamics for a
torus-like black hole in Einstein-Maxwell theory and a charged Einstein-Euler-Heisenberg AdS black hole in Einstein-Euler-Heisenberg nonlinear electrodynamics.
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High Energy Physics (Phenomenology)
Polarization and correlation effects in $\gamma\gamma \to W^-W^+$ at Next-to-Leading-Order Electroweak Accuracy
Jun Jiang, Peng-Cheng Lu, Zongguo Si et al. (+2 more)
We study the next-to-leading order (NLO) electroweak (EW) corrections to the polarization and correlation of $W$
boson pairs produced through
photon-
photon fusion in
proton-
proton ultra-peripheral collisions at the LHC, with both $W$
bosons decaying leptonically. The azimuthal correlation distributions of the charged
leptons, which receive no contribution from anomalous quartic gauge couplings (AQGCs) at linear order, are perturbatively stable at the 0.40% level, whereas individual correlation coefficient $C_{2,2}$ receives relative corrections of up to $-33.84\%$. Some of correlation coefficients that vanish at leading order (LO) in the Standard Model but are sensitive to AQGCs acquire non-zero one-loop values of order $10^{-4}-10^{-3}$. We quantify the region of the ($a_0/\Lambda^2,a_c/\Lambda^2$) plane in which these loop-induced baselines compete with the AQGC contributions and find that, while irrelevant at the current experimental sensitivity, they must be included once the correlation coefficients are measured at the per-mille level.
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All authors Jun Jiang, Peng-Cheng Lu, Zongguo Si, Han Zhang, Xin-Yi Zhang
High Energy Physics (Phenomenology)
ALP photo-production in the parton and hadron cascade model PACIAE
Dai-Mei Zhou, Zhi-Lei She, Jian Cao et al. (+6 more)
In this work, the parton and
hadron cascade model PACIAE is employed to simulate the events of Au+Au collisions at $\sqrt{s_{NN}}=$200 GeV within the 60-80 % centrality interval. Based on the abundant
photons in final hadronic state, the statistical-mechanics-based coalescence model DCPC is applied to phenomenologically recombine post-freeze-out
photon pairs into
axion-like particles (ALPs) for the first time. The coalescence probability is constrained by the branching-ratio $B_r(a \rightarrow \gamma\gamma)=0.57$ under the threshold of twice of $K$
meson mass. The ALP observables including yields, transverse-momentum distributions and rapidity spectra are calculated for several
benchmark ALP-mass bins. These theoretical predictions are worthy to be investigated by the experiments.
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All authors Dai-Mei Zhou, Zhi-Lei She, Jian Cao, An-Ke Lei, Wen-Chao Zhang, Hua Zheng, Li-Lin Zhu, Yu-Liang Yan, Ben-Hao Sa
Quantum Physics
A 75-mL intrinsically stable atom-filtered laser enabling deployable quantum devices
Zijie Liu, Zheng Xiao, Zhiyang Wang et al. (+10 more)
Numerous
quantum devices require
lasers strictly locked to atomic transitions. Atom-filtered
lasers (AFLs) are considered a leading candidate for
quantum device
laser sources due to their ability to self-align to atomic transitions. However, the sub-GHz sharp transmission spectra of conventional atomic filters impose constraints on both
laser miniaturization and output stability. Herein, we demonstrate a micro Faraday anomalous dispersion optical filter ({\mu}FADOF) operating within the extreme hyperfine Paschen-Back regime, generating a 7.5 GHz flat-top transmission window. By integrating this filter, the miniaturization bottleneck of the AFLs is overcome, achieving a 30-fold volume reduction to a compact package volume of 75 mL. Simultaneously, investigations into the optical self-feedback characteristics of the {\mu}FADOF reveal a stable operating regime, where the optical self-feedback of the atomic filter acts as a stabilizing mechanism, enabling the
laser to achieve a power instability of 9 x 10^-6 at 1 s and 3.2 x 10^-5 at 8400 s. The optical frequency standard based on this 75-mL AFL achieves a further improvement in long-term frequency stability to 3 x 10^-13 at 10000 s and maintains turn-key operation under environmental shocks, highlighting the critical role of this
laser in the development of deployable
quantum devices.
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All authors Zijie Liu, Zheng Xiao, Zhiyang Wang, Xiaolei Guan, Xiaomin Qin, Suyang Wei, Hongtian Song, Baoshuai Wang, Jia Zhang, Xiaopeng Xie, Tiantian Shi, Anhong Dang, Jingbiao Chen
Quantum Physics · Cross-listed from cs.LG
Quantum Reinforcement Learning for Cost and Delay Tradeoffs in Quantum Cloud Orchestration
An N. H. Phan, Dang Van Huynh, Muhammad Usman et al. (+1 more)
Quantum cloud computing, delivered through the
quantum-as-a-service (QaaS) model, provides access to
quantum computing resources. However, applying uniform time-based pricing across fundamentally heterogeneous
quantum resources significantly complicates task orchestration, particularly when addressing the tradeoff between execution costs and system performance. While heuristic methods rely on predefined scheduling rules, classical deep reinforcement learning (DRL) models may require more trainable parameters in this setting. Motivated by the potential of parameterised
quantum circuits (PQCs) as compact function approximators, we propose QRLQ, a cost-delay-aware
quantum cloud scheduling framework integrating PQCs with a dueling double deep Q-network (D3QN) to dynamically account for both cost and delay. Our simulation results show that QRLQ achieves lower mean cost and delay than the heuristic baselines, achieving a 5-11% lower mean cost relative to availability-based and rotation-based heuristics and reducing mean delay by 17% and 82% relative to the strongest and weakest heuristic baselines, respectively, while retaining execution fidelity within 2% of a fidelity-greedy policy. Compared with the classical DRL baseline, QRLQ achieves comparable scheduling performance while using 72% fewer trainable parameters. This work explores the feasibility of using QRL for task orchestration in
quantum cloud environments and demonstrates its potential for cost-delay-aware
quantum resource management.
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All authors An N. H. Phan, Dang Van Huynh, Muhammad Usman, Hoa T. Nguyen
Earth and Planetary Astrophysics
Dynamical Behavior and Surface Features of Large Super-Fast Rotator Near-Earth Asteroid (436724) 2011 UW158
Caio Gomes, Andre Amarante, Filipe Monteiro et al. (+7 more)
The sub-kilometer Super-Fast Rotator and Potentially Hazardous Asteroid (436724) 2011 UW158 exhibits an extreme dynamical environment driven by its rotational period of 0.61072 h. Using a 3-D polyhedral shape model, we investigate the surface dynamic stability under both cohesionless and cohesion-modified conditions, while also addressing families of periodic orbits, station-keeping maneuvers, and energy states in this rapidly rotating, irregular-body regime. Our results show that, with the inclusion of cohesion, the effective slopes decrease to ~45{\deg}, permitting the retention of boulders with maximum sizes of ~50 m near the equatorial region. The dominance of the centrifugal term in the effective potential shifts the exterior
equilibrium points inward, creating highly unstable geopotential regions where loose regolith is susceptible to ejection, preventing long-term surface retention outside the polar regions. To quantify this instability, we introduce the equivalent instability speed ($v_{\mathrm{ei}}$), extending conventional escape speed analyses to the SFR regime. These results are consistent with significant internal cohesion in 2011 UW158, which enables the body to maintain structural integrity under rotational stresses exceeding the classical
spin barrier. Additionally, thermophysical modeling reveals that the super-fast rotation produces a nearly uniform surface temperature distribution. Finally, we apply a spherical harmonics method to compute families of periodic orbits around the asteroid to assess the fuel cost of station-keeping maneuvers at reduced computational cost. Overall, this study characterizes the dynamical environment of 2011 UW158, contributing to the understanding of Super-Fast Rotator asteroids recently identified in LSST survey images.
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All authors Caio Gomes, Andre Amarante, Filipe Monteiro, Alessandra Ferreira, Leonardo Braga, Allan Kardec de Almeida Jr., Duncan Lyster, Nicoli Rocha, Gabriel Damilano, Leonardo Barbosa
Plasma Physics
Calibration of cross-field transport models in SOLPS-ITER on the TCV-X21 case
Stefano Carli, Reinart Coosemans, Claudia Colandrea et al. (+1 more)
Cross-field turbulent transport remains one of the largest uncertainties in edge
plasma simulations and is commonly approximated through empirical transport coefficients. In this work, we calibrate and assess several cross-field transport models implemented in SOLPS-ITER using measurements from the TCV-X21 reference case. The considered models range from conventional constant-diffusivity descriptions to the self-consistent k-model, in which anomalous diffusivities evolve along with
plasma conditions. Model parameters are estimated through gradient-based optimization by minimizing discrepancies between simulated and experimental upstream and divertor profiles in forward field configuration. The calibration results show that increasing the number of free parameters substantially improves agreement with the calibration
dataset. However, these more flexible models exhibit poor predictive capability when applied to the reversed field configuration, indicating overfitting. In contrast, the simplest constant-diffusivity model provides the best overall predictive performance while requiring only a small number of calibrated parameters. The k-model achieves a calibration quality comparable to the constant-diffusivity model and reproduces the experimental profiles with similar accuracy, while simultaneously providing a physics-based description of the spatial variation of anomalous transport. Predictions for a density scan reveal differences that are not apparent near the calibration point. The k-model predicts increasing transport levels around the separatrix with increasing density, leading to broader upstream profiles and an earlier onset of divertor rollover compared to the constant-diffusivity model. The presented framework provides a systematic and efficient route for model calibration in SOLPS-ITER, and a set of calibrated k-model parameters to be employed in future studies.
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All authors Stefano Carli, Reinart Coosemans, Claudia Colandrea, Wouter Dekeyser
Astrophysics of Galaxies
Distance Estimation using Globular Clusters and Ultra-Compact Dwarfs
Bas van Heumen, Jonah S. Gannon, Duncan A. Forbes et al. (+2 more)
The tight scaling relation between absolute magnitude and internal velocity dispersion ($\sigma$) for globular clusters (GCs), referred to as the GC velocity dispersion (GCVD) relation, has shown great potential as a distance
estimator. However, at the high-luminosity end of the GC luminosity function, GCs mix with ultra-compact
dwarfs (UCDs). As GCs appear to smoothly transition into UCDs with dynamical mass, we investigate the possibility of a unified distance estimation relation applicable to both GCs and UCDs. To this end, we exploit the transition between scaling relations with dynamical mass, using the Milky Way and M31 GCs alongside literature UCDs. Additionally, we look at the influence of UCDs, and of GC size, on GCVD-derived distances. Using the GCVD for UCDs gives a systematic distance underestimation of $\sim$33 per cent, but a cut to select UCDs with GC-like sizes can eliminate this bias. The minor systematics on GC size produce systematic offsets smaller than the uncertainty of the GCVD. Using the bilinear relation formed by the GCs and UCDs in the absolute magnitude - log dynamical mass plane for distance estimation yields per-object distance uncertainties of $\sim$30-35 per cent (0.12-0.16 dex). We find that the GC - UCD division occurs at $M_V \simeq -10.8$ mag and $M_{dyn} \simeq 3.1\times10^6$ $M_{\odot}$, consistent with previous findings. Applied to the
dwarf galaxy NGC1052-DF2, whose distance is strongly debated, the relation returns 19.1 $\pm$ 4.3 Mpc, consistent with literature values.
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All authors Bas van Heumen, Jonah S. Gannon, Duncan A. Forbes, Jean P. Brodie, Aaron J. Romanowsky
Optics
Boundary singular scattering enables coherent perfect absorption and lasing without resonators
Letian Yu, Xu Zheng, Cesare Soci et al. (+2 more)
Scattering singularities are features conventionally associated with resonant scattering bodies, which correspond to the zeros and poles of a scattering
matrix, and manifest as coherent perfect absorption and lasing respectively. Here, we show that they can emerge solely from an interface, eliminating the need for any resonant body. We introduce boundary singular scattering, whereby an interface between two non-Hermitian media supports coherent perfect absorption, lasing, or both. Despite these singular responses, the two adjoining media are in parity-time (PT)-unbroken phases, with entirely real bulk spectra. This phenomenon originates from a singular boundary mode-matching condition unique to non-Hermitian systems, not from any underlying resonant modes. We demonstrate it experimentally in a programmable synthetic photonic
lattice, and show coherent switching between perfect absorption and lasing by controlling only the relative phase of the incident beams. The same mechanism further generalizes from mirror-symmetric interfaces to asymmetric interfaces with dissimilar bulk dispersions. Our work establishes boundaries as a previously unexplored origin of scattering singularities, opening a resonator-free route to coherent perfect absorption, lasing, and other singular wave phenomena.
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All authors Letian Yu, Xu Zheng, Cesare Soci, Y. D. Chong, Baile Zhang
Statistical Mechanics
Uphill and downhill first passage of an active Brownian particle: Asymmetry and exact path reweighting
Mykola Tasinkevych, Xuan My Le and Artem Ryabov
First passage processes in active systems combine
stochastic transport with self-propulsion and orientational persistence, making motion along and against an external bias sensitive to the internal active dynamics. For passive biased
diffusion, opposite exits can have different splitting probabilities while their conditional first passage time distributions remain identical. We study how this relation changes for an active Brownian particle driven by a constant external force between two absorbing boundaries. Self-propulsion breaks the equality of the uphill and downhill first passage time distributions and modifies the splitting probabilities. Nevertheless, the two directional path ensembles remain exactly related by spatial reflection, which pairs downhill and uphill first passage paths of the same duration while preserving their orientational history. The log-ratio of the probabilities of a path and its reflected partner defines a path-dependent asymmetry functional and provides an exact reweighting between the two ensembles. In the symmetric half-weighted representation, the uphill and downhill first passage time distributions coincide for arbitrary orientational persistence. The same path relation also allows rare uphill statistics to be reconstructed from the more frequently sampled downhill trajectories. Numerical simulations confirm the weighted equality across the explored bias and persistence regimes, while perturbative and asymptotic analyses clarify how orientational persistence produces the directional asymmetry of the unweighted statistics. The exact relation between the two directional path ensembles suggests that similar
symmetry-based reconstruction protocols may be found in other nonequilibrium first-passage problems.
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Mathematical Physics · Cross-listed from math.RA
Zhongyin Xu and Chengming Bai
We construct a graded Lie
algebra structure on the space of cyclically skew-symmetric cochains whose Maurer-Cartan elements characterize double Lie
algebra structures. Twisting by a fixed double Lie bracket yields a cochain complex that is isomorphic to the positive arity part of the complex introduced by Fairon and Valeri after reindexing and degreewise sign adjustment. Using the Koszul resolution of the double Lie properad, we identify the resulting differential graded Lie
algebra with the convolution differential graded Lie
algebra on the deformation complex of the fixed double Lie
algebra. We also construct a graded Lie
algebra governing skew-symmetric Rota-Baxter operators on a finite-dimensional symmetric Frobenius
algebra. For a finite-dimensional vector space $V$ and $A=\en(V)$, we lift the known correspondence between double Lie
algebra structures on $V$ and skew-symmetric Rota-Baxter operators on $A$ to an isomorphism of their governing graded Lie
algebras. After twisting by corresponding Maurer-Cartan elements, this isomorphism becomes an isomorphism of differential graded Lie
algebras and hence induces an isomorphism between the associated
cohomology groups. We further prove that the
cohomology of a skew-symmetric Rota-Baxter operator on a symmetric Frobenius
algebra can be seen as the cyclic
cohomology of its descendent associative
algebra. Thus the
cohomology of a double Lie
algebra is identified with the cyclic
cohomology of the descendent associative
algebra associated with the skew-symmetric Rota-Baxter operator on the
matrix algebra.
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Earth and Planetary Astrophysics
The Dynamical Environment of Kepler-223 Planetary System
Carlos E. Chavez, Adrián Fierro and Ándres Avilés
The Kepler space
telescope was a successful mission that used the transit method. Multi-planetary systems are interesting because they are dynamically rich due to the
planets' interactions. Kepler's mission was the first to find a system with four
planets all in resonance, that is Kepler-223. The Kepler-223 system is of unique dynamical interest as the first exoplanetary system confirmed to host four sub-Neptune
planets in a precise 3:4:6:8 resonant chain. Previous dynamical studies have struggled to fully recover the long-term phase protection mechanisms, often finding that higher-order resonant angles circulate rather than librate. In this work, we re-examine the dynamical state of Kepler-223 by performing high-resolution N-body integrations and constructing detailed stability maps in the (a,e) phase space, we demonstrate that the system is locked in a deeper resonant state than previously thought. Crucially, we find that all resonant arguments, exhibit robust libration over secular timescales. Our stability maps reveal that the
planets reside in clearly defined stability islands that allow for higher eccentricities than previous estimates. We further compare these numerical islands with analytical resonance widths and find excellent agreement for the inner three
planets, while the outermost
planet (Kepler-223e) exhibits a stability region wider than first-order analytical theories predict, suggesting complex multi-body stabilization effects at the edge of the chain.
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Soft Condensed Matter
Multigeometric Breathing Mode Framework for viruses
Krish Bardhan, Charu Sharma, Shivansh Bhatnagar et al. (+1 more)
The estimation of the breathing mode frequency for viral capsids remains a persistent challenge across literature which spawned various frameworks and methodologies. However, discrepancies were observed between the experimental Low Frequency Raman Scattering (LFRS) and calculated pre-existing values. To solve this discrepancy, we propose a framework which is developed to determine the breathing-mode frequency by modelling the virus as a macroscopic coupled harmonic oscillator. By integrating mass-loading directly into the classical elastodynamic equations, this model yields an analytical expression that couples the system's total inertia with its specific geometry. Moreover, the viruses are segregated according to their geometries into three coordinates to acquire their respective
geometric eigen values. Here we illustrate how the proposed Multigeometric Breathing mode Framework for Virus (MBFV) outperforms prior models by yielding closer values than the pre-existing frameworks upon validating against LFRS.
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All authors Krish Bardhan, Charu Sharma, Shivansh Bhatnagar, Prafulla K Jha
Quantum Physics
Antiblockade Quantum Batteries
Guohui Dong and Yao Yao
Blockade, a phenomenon in which one particle hinders the transport of another, constitutes a core research topic in mesoscopic and microscopic physics. Benefiting from the unique single-particle characteristics, it underpins versatile applications spanning from
quantum computation to
quantum metrology. Nevertheless, in the context of
quantum energy?storage devices, i.e.,
quantum batteries (QBs), blockade triggered by the intrinsic level splitting is in turn detrimental to energy accumulation. Here we propose an antiblockade charging protocol enabled by deliberately engineering a bright-dark interaction. Rooted in a
manifold of equally-spaced dressed-dark states, this elaborate configuration opens up a new charging channel facilitating an antiblockade energy flow and outperforms the Rabi-split blockade design with at least a 20-fold enhancement in energy storage. Additionally, we further illustrate the achievement of superextensive (quadratic) charging characteristic by operating the system in the bad-cavity limit. In view of its inherent generality, our scheme offers a universal and feasible pathway toward high-performance
quantum energy architectures.
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Materials Science
Physics-guided inverse design of Co-based superalloys using machine learning and multi-objective optimization for enhanced $\gamma'$ solvus temperature
Prashil S. Joshi
The discovery of next-generation Co-based superalloys with improved high-temperature stability is hindered by the vast compositional design space and complex interactions among alloying elements governing gamma-
prime phase stability. This study presents a physics-informed machine learning framework for the inverse design of Co-based superalloys with higher gamma-
prime solvus temperature while accounting for
alloy density. Four descriptors representing atomic size mismatch (delta-MV), mixing enthalpy (Delta-Hm), electronegativity mismatch (delta-EN), and valence electron concentration mismatch (delta-VEC) were used to characterize the chemistry governing phase stability. Regression
algorithms were evaluated using leave-one-out cross-validation, with Gaussian Process Regression (GPR) achieving the best performance (R2 = 0.932, RMSE = 34.7 deg C, and MAE = 25.9 deg C). The probabilistic nature of GPR enabled uncertainty-aware
Bayesian optimization for exploring the uncharted composition space. Non-dominated Sorting Genetic
Algorithm II (NSGA-II) and Genetic
Algorithms were used to simultaneously increase gamma-
prime solvus temperature and reduce
alloy density. The optimization generated numerous previously unexplored Co-based
alloy compositions, with predicted gamma-
prime solvus temperatures of 1248-1353 deg C, including candidates approaching or exceeding the maximum value in the experimental
dataset. Descriptor analysis identified atomic size mismatch and mixing enthalpy as key factors governing gamma-
prime stability, while principal component analysis confirmed that the proposed
alloys occupy chemically relevant descriptor regions. This physics-informed inverse design framework provides an efficient route for identifying high-performance Co-based superalloys and can be adapted to other advanced structural
alloys.
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Nuclear Theory
Multi-Model Analysis of the Astrophysical $S(E)$ Factor for the $^{9}\mathrm{Be}(p,\alpha)^{6}\mathrm{Li}$ Reaction and Its Impact on Astrophysical Reaction Rates
Xue-Jian Wang, Wei-Ke Nan, Qing Wang et al. (+5 more)
The $^{9}\mathrm{Be}(p,\alpha)^{6}\mathrm{Li}$ reaction is a destruction process for $^{9}\text{Be}$ in
stars and the Big Bang. The Trojan Horse Method (THM) is a well-established indirect technique that enables the determination of reaction cross sections within the Gamow energy region while avoiding the uncertainties associated with low-energy extrapolations of the $S(E)$ factor and electron-screening effects. In this work, the bare-
nucleus THM data reported by Wen et al. are systematically analyzed using
polynomial fitting, a double Breit–Wigner model, and the $R$-
matrix formalism. The applicability and physical implications of these theoretical approaches in describing the low-energy $S(E)$ factor of the $^{9}\mathrm{Be}(p,\alpha)^{6}\mathrm{Li}$ reaction are investigated and compared. Since the THM data have been incorporated into the NACRE II reaction-rate compilation, leading to improved accuracy in reaction-rate evaluations, the refined theoretical analysis presented here provides further insight into the underlying reaction dynamics and establishes a more reliable foundation for
stellar reaction-rate calculations. The results obtained in this work offer valuable reference for future high-precision experimental investigations and the development of theoretical models in
nuclear astrophysics.
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All authors Xue-Jian Wang, Wei-Ke Nan, Qing Wang, Tian-Yu Tao, Qun-Gang Wen, Jian-You Guo, Cheng-Bo Li, Hui-Ming Jia
Medical Physics
Integration of Spectral CT with PET and SPECT: Bringing Tissue Composition Information to Molecular Imaging
Guobao Wang, Kris Thielemans, Peter B. Noël et al. (+2 more)
Molecular imaging has been transformed by integrating positron emission
tomography (PET) or single-
photon emission computed
tomography (SPECT) with x-ray computed
tomography (CT). However, x-ray CT in hybrid imaging is used primarily for anatomical localization and for attenuation and scatter correction of emission data. Its ability to characterize tissue composition remains underutilized. Spectral CT, including dual-energy CT (DECT) and
photon-counting CT (PCCT), can provide material-specific information, such as images of iodine concentration, bone or calcium fractions, electron-density, effective atomic number and other spatially-varying material properties. These capabilities create an opportunity to bring tissue-composition information into molecular imaging. In addition, spectral CT can also reduce CT artifacts and provide more accurate corrections for emission data. In this review, we discuss the technical basis, integration pathways, and translational opportunities for combining spectral CT with molecular imaging. We review sequential and integrated PET/DECT approaches, emerging PET/PCCT concepts, PET-enabled spectral CT, and extensions to SPECT/CT. We then examine how spectral CT information may improve attenuation correction, scatter correction, tissue-fraction correction, positron range correction, reconstruction priors, and dosimetry. Clinical and translational applications include contrast-enhanced molecular imaging, vascular and perfusion imaging, quantitative bone marrow imaging, musculoskeletal imaging, and theranostics. Overall, spectral CT integration may move hybrid molecular imaging toward tissue-composition-informed molecular imaging, in which radiotracer signals are interpreted within their material context.
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All authors Guobao Wang, Kris Thielemans, Peter B. Noël, Joel S. Karp, Paul E. Kinahan
High Energy Astrophysical Phenomena
Estimating redshift distributions of Fermi blazars with multiple machine-learning models
Kerui Zhu, Jiaming Chen, Yonggang Zheng et al. (+4 more)
Approximately half of the
Fermi-LAT-detected blazars lack spectroscopic
redshift measurements, which limits population studies and investigations of the cosmological
evolution of the gamma-ray blazar population. We aim to develop a multi-model ensemble framework to systematically evaluate the performance of machine-learning models for blazar
redshift estimation and to provide predictive
redshift probability distributions with quantified uncertainties for all blazars without measured
redshifts. We construct an ensemble of 35 machine-learning regression models in the $1/(1+z)$ space. Predictions from individual models are combined to build non-parametric
redshift probability density functions (PDFs) for each source, allowing an explicit characterization of predictive uncertainty. The source-level PDFs are subsequently stacked to derive population-level
redshift distributions. Across the diverse models within our framework, we find comparable predictive performance, indicating a feature-limited performance plateau. We compile a catalog of predictive
redshift distributions for 1,590 blazars without measured
redshifts. The stacked PDFs recover the characteristic double-peaked
redshift structure of blazars without using source class labels. For blazar candidates of uncertain type, the predicted
redshift distribution exhibits a bimodal structure, suggesting a slightly larger contribution from FSRQ-like sources. Our multi-model statistical framework achieves competitive predictive performance while retaining faint sources. We provide predicted
redshift distributions with quantified uncertainties for 1,590 blazars without measured
redshifts, offering improved support for population and evolutionary studies. More broadly, this approach highlights the practical value of uncertainty-aware multi-model regression ensembling in astronomical data analysis.
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All authors Kerui Zhu, Jiaming Chen, Yonggang Zheng, Ruixin Zhou, Shan Chang, Li Zhang, Niansheng Tang
Materials Science
Fractionation as a Tool to Control Mn/Al Site Mixing and Magnetism in CaMn_{2+x}Al_{10-x}
Szymon Królak, Sushma Kumari, Sergey L. Bud'ko et al. (+1 more)
We report single
crystal growth and physical property characterization of CaMn_{2+x}Al_{10-x}
crystals grown using a fractionation approach. Three consecutive batches were obtained from the same initial melt composition, systematically sampling neighboring, narrow regions of the ternary Ca-Mn-Al phase diagram. Single-
crystal X-ray diffraction measurements reveal Mn/Al site mixing, with the excess Mn concentration, x, decreasing systematically with decreasing decanting temperature. A low-temperature upturn in magnetization and a maximum in electrical resistivity both become progressively weaker with decreasing excess Mn content, suggesting that the previously reported
magnetic properties attributed to stoichiometric CaMn_{2}Al_{10} instead arise from an inhomogeneous distribution of excess Mn atoms. More broadly, the results presented in this work demonstrate how fractionation can help distinguish intrinsic
magnetic behavior from disorder-induced effects associated with an inhomogeneous distribution of
magnetic ions in materials with a finite width of formation, particularly when itinerant magnetism is under consideration.
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All authors Szymon Królak, Sushma Kumari, Sergey L. Bud'ko, Paul C. Canfield