Materials Science
Single-Crystalline Al/Ge Heterostructure with an Atomically Sharp Commensurate Interface
Jian-Huan Wang, Ding-Ming Huang, Han Gao et al. (+3 more)
A key challenge in developing Al/Ge
heterostructures for
quantum applications is Al-Ge interdiffusion. This process is facilitated by grain boundaries in polycrystalline films, which degrades interface quality and impairs device performance and reliability. Here, we present epitaxial growth of single-crystalline Al(111) on Ge(111) by molecular beam epitaxy, achieving an atomically flat and sharp interface. At the interface, a commensurate 7-Al-
lattice/5-Ge-
lattice epitaxial relationship is observed, which dramatically reduces the intrinsic
lattice mismatch from 28.4% to about 0.1%. Interestingly, this well-ordered interface does not form below a critical thickness of 0.3 nm. Instead, Al initially nucleates as random clusters, which then transform into two-dimensional (2D) islands and, as Al deposition further increases, eventually develop into a continuous film. By optimizing the growth parameters, we have achieved an ultra-flat Al film with a surface root-mean-square roughness of about 0.16 nm and an ultra-thin continuous film with thickness of only 2 nm. These epitaxially grown Al-Ge
heterostructures, with their atomically flat surfaces and sharp interfaces, provide a promising platform for studying topological
quantum states.
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All authors Jian-Huan Wang, Ding-Ming Huang, Han Gao, Yuan Yao, H. Q. Xu, Jian-Jun Zhang
Astrophysics of Galaxies
MSA-3D: Rotation Curves and Dark Matter Fractions at z~0.5-1.7 with JWST/NIRSpec
Juan M. Espejo Salcedo, Danail Obreschkow, Karl Glazebrook et al. (+17 more)
We present rotation curves and inner mass distributions for 30
star-forming
galaxies at $0.5<z<1.7$, observed with JWST/NIRSpec as part of the MSA-3D Cycle 1 survey. Combining spatially resolved ionised-gas kinematics with JWST/NIRCam imaging, we constrain baryonic and dark matter contributions through forward dynamical modelling for
galaxies extending down to
stellar masses of $\sim10^{9}M_\odot$. For the 23
galaxies in our primary statistical sample, we find predominantly rotationally supported disks with intrinsic dispersions $\sigma_0\sim31$-65 km s$^{-1}$ and a wide range of dark matter fractions, $f_{DM}(R_e)\sim0.1$-0.9, with a median of 0.63 and substantial
galaxy-to-
galaxy scatter of $\sim0.2$ dex. These results are supported by a complementary consistency check using
stellar mass maps and SFR-derived gas profiles. Among the 19
galaxies reaching $\gtrsim2R_e$, we identify six rising, six flat, and seven falling rotation curves. These classes define an observed ordering from rotationally dominated, dark-matter-rich disks ($V_{rot}/\sigma_0\approx4$, $f_{DM}\gtrsim0.7$) to more dispersion-supported systems with centrally concentrated baryonic mass distributions ($V_{rot}/\sigma_0\approx2$, $f_{DM}\lesssim0.55$). The
stellar Tully-Fisher relation lies close to the local relation evolved under the adopted self-similar $\Lambda$CDM scaling. A simplified seeing-degradation test shifts the inferred normalisation by ~0.2 dex at fixed $V_c$, suggesting that spatial resolution contributes to, but does not fully explain, differences among high-
redshift Tully-Fisher measurements. Overall, MSA-3D provides a high-resolution extension of previous surveys toward lower
stellar masses, spanning $9.0 < \log(M_\star/M_\odot) < 11.2$, and reinforces that
star-forming disks near $z\sim1$ span a broad range of dynamical states and inner mass distributions.
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All authors Juan M. Espejo Salcedo, Danail Obreschkow, Karl Glazebrook, Tucker Jones, Ivana Barišić, Natascha M. Förster Schreiber, Takafumi Tsukui, Xin Wang, Mengting Ju, Qianqiao Zhou, Amit Nestor-Schachar, Ryan L. Sanders, Stavros Pastras, Namrata Roy, Alaina Henry, Kyle Westfall, Themiya Nanayakkara, Matthew Malkan, Fahmi M. Al Farisy, Isaac Kanowski
High Energy Astrophysical Phenomena
Mass-Ratio Reversal as an Alternative to Hierarchical Mergers for GW241011
Rui-Chong Hu, Ying Qin and Bing Zhang
Recent gravitational-wave (GW) observations have revealed binary black hole (BBH) mergers with both extreme mass ratios and large effective
spin parameters ($\chi_{\rm{eff}}$). GW241011 is a notable example that shows these properties. Although hierarchical mergers (second-generation + first-generation BHs) can naturally produce high
spins and become more prevalent than first-generation + first-generation mergers at mass ratios $q \lesssim 0.6$, they are negligible at the extreme mass ratio $\sim 0.3$ and are further limited by gravitational
recoil kicks that can eject the second-generation BH from the host environment. Moreover, recent studies have argued against a dynamical origin for GW241011. Here, we investigate the formation of GW241011-like systems through the mass-ratio reversal (MRR) channel in isolated binary
evolution. By quantifying the probability of producing such systems across a range of binary-
evolution models, we identify the key dependencies on
stellar-
evolution and binary-interaction physics. Our results demonstrate the conditions under which the MRR channel can provide a viable alternative to hierarchical mergers for GW241011-like events, although its predicted merger rate density remains relatively low.
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High Energy Physics (Theory)
Tree-level S matrix for $\lambda$-deformed AdS3 strings
Marco Costantino, Silvia Penati and Alessandro Sfondrini
We consider the supersymmetric $\lambda$-deformation of $\text{AdS}_3 \times \text{S}^3 \times \text{T}^4$ superstrings and compute its perturbative bosonic tree-level worldsheet S
matrix in the light-cone gauge. For generic values of $0 \leq \lambda < 1$, we show that the worldsheet scattering remains compatible with integrability due to a non-trivial cancellation of non-elastic scattering processes. By contrast, the S
matrix becomes ill-defined for $\lambda \to 1$, despite the fact that this limit reproduces the non-Abelian T-dual geometry up to an analytic continuation. This suggests that the $\lambda \to 1$ limit does not capture the full worldsheet dynamics of the T-dual theory.
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High Energy Physics (Theory)
Classification of Killing Horizons in D=11 Supergravity
Jan Gutowski, Chettha Saelim and Martin Wolf
We initiate the classification of supersymmetric degenerate Killing horizons, with closed spatial cross section, away from the near-horizon limit in D=11 supergravity. We prove that all such solutions fall into two distinct classes, depending on lightcone chirality with respect to a Gaussian null coordinate system. For the first class of solutions, the negative lightcone chirality part of the Killing spinor is non-zero on the Killing horizon, and we prove that all such solutions are isometric to supersymmetric near-horizon geometries. In the second class, the negative lightcone chirality part of the Killing spinor vanishes on the Killing horizon. In this case, we prove that the spinorial Lie derivative of the Killing spinor with respect to the Killing vector which generates the Killing horizon vanishes, and that all such solutions with more than 13 supersymmetries are pp-waves.
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High Energy Astrophysical Phenomena
Polarimetry of Ultraluminous X-ray sources
Haruka Sakemi
Ultraluminous X-ray sources (ULXs) are non-
nuclear X-ray emitters exceeding the Eddington luminosity, offering key insights into extreme
accretion physics. Their origin is attributed to either sub-Eddington
accretion onto intermediate-mass black holes (IMBHs) or supercritical
accretion onto
stellar-mass compact objects in binary systems. A subset of ULXs shows
radio jets and surrounding bubbles, indicative of strong mechanical feedback, but no polarization detection has been reported to date because of limited sensitivity and angular resolution at multi-megaparsec distances. Next-generation facilities such as the Square Kilometre Array (SKA) will enable polarimetric studies of ULX
outflows and bubbles, providing vital information on their
magnetic field structure and jet-ISM interactions. Using Holmberg II X-1 (3.39 Mpc) as a representative system, we evaluated the detectability of its polarized jet and bubble with the SKA-Mid AA4 configuration. Assuming a fractional polarization of 20% and Band 2 observations centered at 1310 MHz, the expected polarized intensities are 260 $\mu$Jy beam$^{-1}$ for the jet and 20 $\mu$Jy beam$^{-1}$ for the bubble. A Holmberg II X-1-like jet is detectable within 10 hours even at $\sim$ 10 Mpc, while bubble polarization requires $\sim$ 100 hours. Although resolving fine structures is feasible only for nearby ULXs, future SKA-VLBI capabilities will help overcome this limitation and enable detailed mapping of
magnetic field morphology. These results indicate that the SKA will enable the first detection of polarized emission from ULXs, advancing our understanding of
magnetic field geometry, jet formation, and feedback in super- and sub-Eddington accretors.
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Quantum Physics
Quantum LiDAR with non-local modulation
Xiao-Dong Fan, Zhong-Hua Ou, Yun-Ru Fan et al. (+13 more)
Quantum light detection and ranging (
LiDAR) utilizes
quantum entanglement and correlation to improve precision, noise resilience and covertness of target detection. Despite recent advances, the development of a
quantum LiDAR system that simultaneously achieves high precision and a large measurement range remains challenging. Here, we demonstrate a
quantum amplitude-modulated continuous wave
LiDAR with micrometer precision achievable via increased acquisition time and meter-scale measurement range. In our demonstration, the signal
photons directly illuminate the target, while the idler
photons are non-locally modulated with a high-frequency cosine wave and never interact with the target. By leveraging the non-local modulation and the
quantum correlation, the target detection is achieved with a precision of 0.64 $\pm$ 0.06 mm within one second over a measurement range of 2-8 m. As the acquisition time is up to 500 s, the system achieves a precision of 29 $\pm\ 4{\ \mathrm{\mu m}}$. Furthermore, our system realizes a 50 times precision improvement over the classical single-
photon scheme in a background noise 37 dB stronger than the returned probe
photons. With these advantages, our method will open venues for the development of high-precision, long-range, and noise-resilient target detection.
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All authors Xiao-Dong Fan, Zhong-Hua Ou, Yun-Ru Fan, Kai Guo, Zong-Liang Xie, Qiang Qi, Li-Xun Zhang, Si Shen, Hai-Zhi Song, Yan-Yu Wei, Hao Li, Li-Xing You, Qi Zhang, Yong Liu, Guang-Can Guo, Qiang Zhou
High Energy Physics (Phenomenology)
Leptonic CP Conservation and the Quark CP Phase from Octonionic Flavor Structure
Bishnu Gupta Teli and Tejinder P. Singh
One generation of standard-model
fermions can be realized on the complexified octonions through the Clifford
algebra $\mathcal{C}l(6)$; the octonionic unification programme extends this to three generations, with generation transport implemented by $G_2$
automorphisms or by rotors built from the ladder operators. We prove a localization
theorem for the CP-violating phases of this structure, using only the $\mathcal{C}l(6)$ construction and the stated three-generation representatives, independently of the wider programme. For
quarks, the first-to-second generation step is the occupation flip of one ladder mode, with the up and down species coupling to conjugate ladder directions; a conjugation
theorem forces $A_d=A_u^*$ for every real transport, and the most general rung-generated rotor yields the exact one-parameter law $\phi_{12}=-2\chi$: the $(1,2)$ transport phase is twice one Yukawa orientation angle. The programme's
geometric rotor sits exactly at the quadrature-balanced point $|\phi_{12}|=\pi/2$; the companion analysis reproduces the Cabibbo magnitude $|V_{us}|$ with a single real tilt, leaving the rung near quadrature, but it does not extract a CKM CP phase, so the
quark Dirac phase is fixed only once the underlying Yukawa orientation is computed. For
leptons we prove a reality
theorem: every charged-
lepton and every
neutrino transport amplitude is exactly real for every $G_2$
automorphism and every rotor that does not mix the identity line $\mathbb C\cdot1$ with the
lepton–
flavor plane $\mathrm{span}(e_7,e_5,e_2)$ a class that contains the entire
quark-rung family–and identity–
flavor mixing across that plane is the unique possible source of a leptonic phase. [Truncated]
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Statistical Mechanics
Rare Events Govern Defect Formation under Weak Symmetry Breaking
Jiang Liu, Peng Yang and Matteo Baggioli
Crossing a continuous phase transition out of
equilibrium typically generates topological defects whose density obeys a universal power-law scaling predicted by the Kibble-Zurek mechanism. Recent numerical studies have revealed systematic deviations from this scaling in the presence of weak explicit
symmetry breaking, manifested as an additional exponential suppression of defect formation. However, the origin of this correction and a general theoretical framework to describe it have remained elusive. Here, using large-deviation theory, we show that defect formation under weak
symmetry breaking is controlled by rare fluctuations that drive local regions into the disfavored
symmetry-broken state. Within mean-field theory, this mechanism yields a closed-form expression for the defect density in arbitrary dimensions, valid in the weak-field and weak-noise limits. These theoretical predictions are verified through direct simulations of
stochastic Ginzburg-Landau models in one and two spatial dimensions.
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Plasma Physics
Collisionless dynamo seeds from phase mixing-induced electron slippage
István Pusztai, Lise Hanebring and James Juno
Magnetic fields permeating the Universe on the largest astrophysical scales are thought to result from dynamo amplification in weakly collisional
turbulence, but the origin of the seed fields remains an open problem of
cosmic magnetogenesis. We identify a kinetic mechanism for
magnetic-field generation in initially unmagnetized, collisionless
plasmas, arising from phase-mixing-induced braking of spatially varying electron flows. Using analytical theory, fully kinetic Vlasov simulations, and turbulent scaling arguments, we show that this process generates coherent
magnetic seed fields on scales far larger than the characteristic kinetic scales of the
plasma, with strengths comparable to or exceeding classical Biermann battery estimates. The mechanism requires neither a finite initial
magnetic field nor misaligned thermodynamic gradients and occurs naturally in electron-ion
plasmas.
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Mesoscale and Nanoscale Physics
Theory of Electron Spin Resonance Scanning Tunneling Microscopy: The First Decade
Saba Taherpour, Denis Janković, Jose Reina-Galvez et al. (+2 more)
Electron
spin resonance in scanning tunneling microscopy enabled the study of electronic transitions of
magnetic impurities on surfaces at the atomic scale. This ESR-STM technique allows to spectroscopically probe and coherently manipulate
spins using an all-electrical method without oscillating external
magnetic driving fields. Here, we aim to review recent advancements in ESR-STM. We will discuss possible fundamental mechanisms by which the electric field drives
spin resonance based on Heisenberg exchange, Kondo scattering, and Anderson
impurity models. We validate theoretical predictions against experimental observations, to understand how electronic correlations,
spin exchange, and many-body effects manifest in ESR-STM signals. After reviewing coherent
spin control in the STM junction, we discuss potential applications of the ESR-STM method for coherent multi-
spin control which enables multiple-
qubit operations. Finally, we address recent developments in coupled electron-
nuclear spin systems, including hyperfine-resolved ESR spectroscopy, and the driving and polarization of
nuclear spins in ESR-STM.
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All authors Saba Taherpour, Denis Janković, Jose Reina-Galvez, Hoang-Anh Le, Christoph Wolf
Quantum Physics · Cross-listed from math.FA
Factorization through Lorentz cones
Guillaume Aubrun, Francesca La Piana and Alexander Müller-Hermes
A pair of proper cones $(\mathsf{C}_1,\mathsf{C}_2)$ is said to have the Lorentz factorization property (LFP) if every $(\mathsf{C}_1,\mathsf{C}_2)$-positive map factors through a direct sum of Lorentzian cones, i.e., cones over Euclidean balls. Clearly, $(\mathsf{C}_1,\mathsf{C}_2)$ has the LFP if either $\mathsf{C}_1$ or $\mathsf{C}_2$ is a direct sum of Lorentzian cones, and our main goal is to find other examples. We show that such examples cannot be found for pairs $(\mathsf{C}_1,\mathsf{C}_2)$ where $\mathsf{C}_1=\mathsf{C}_2$, or in the case where both $\mathsf{C}_1$ and $\mathsf{C}_2$ are polyhedral. We also focus on the case where $\mathsf{C}_1=\mathsf{C}_\square$ is the square-based cone in $\mathbf{R}^3$. Here, we show that $(\mathsf{C}_\square,\mathsf{C})$ has the LFP whenever $\mathsf{C}$ is a symmetric cone, i.e., a direct sum of Lorentz cones, cones of positive semidefinite
matrices over the real numbers, complex numbers or quaternions, and the cone of $3\times 3$ positive semidefinite
matrices over the octonions. We leave open the question whether there are more examples, but we show that this list cannot be extended by any strictly convex cone $\mathsf{C}$ or for a cone $\mathsf{C}$ with $\text{dim}(\mathsf{C})\leq 5$. Finally, we discuss an application to a problem in
quantum information theory.
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Quantum Gases
Universality in strongly interacting bosonic clusters
L. Madeira, F. Pederiva and U. van Kolck
We develop an effective field theory (EFT) for strongly interacting bosonic clusters, using $^4$He as a paradigmatic example of universality in systems with large scattering length. At leading order (LO), two- and three-body zero-range interactions are entirely determined by the dimer and trimer ground-state energies. We show that ground-state energies for up to $N=15$ particles converge to cutoff-independent limits with extrapolation coefficients of natural size. At next-to-leading order (NLO), corrections stemming from the two-body interaction range and a four-body force, calibrated to the tetramer ground-state energy, reduce cutoff sensitivity. Close agreement with results from a realistic potential is found at LO and improved at NLO, demonstrating systematic convergence with few parameters at each order. The resulting EFT is directly applicable to larger clusters and bulk helium.
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Astrophysics of Galaxies
An ACA map of a molecular cloud interacting with supernova remnant W28
Tian-Yu Tu, Wenjin Yang, Siyi Feng et al. (+4 more)
Supernova remnants (SNRs) strongly influence the physical and chemical properties of the molecular clouds (MCs) with which they interact. We carried out a high-resolution observation toward W28F, a chemically rich MC interacting with SNR W28, with the Atacama Compact Array (ACA) in Band 7. Significant emission (> 10 sigma) of CO, CH3OH, p-H2CO, SiO and SO is detected. We reveal the clumpy structures of the shocked MC, with different spatial distributions between CH3OH and SiO. We select six molecular clumps to conduct spectral decomposition and non-local-thermodynamic-
equilibrium analysis with the CH3OH and p-H2CO lines. The best-fit results show a H2 density of nH2 ~ (1-3) * 10^5 cm^-3 and a gas temperature of Tgas ~ 50-170 K in most of the fitted components. The H2 density and gas temperature show a clear anti-correlation across different regions, with the thermal pressure consistent with that of the adjacent X-ray-emitting hot
plasma. This is consistent with the picture that the SNR shocks propagate into multi-phase gas, with a pressure balance existing between different phases. We propose that the high abundance ratio between E-CH3OHand A-CH3OH (> 0.9) suggests extra gas-phase processes to enhance this ratio, such as
proton exchange with H3+ and HCO+. The chemical segregation between CH3OH and SiO, in both the spatial and spectral regime, can be explained by the fact that CH3OH traces slow shocks while SiO traces fast shocks.
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All authors Tian-Yu Tu, Wenjin Yang, Siyi Feng, Valentine Wakelam, Yang Chen, Ping Zhou, Qian-Qian Zhang
Quantum Physics
Parameter-Efficient Quantum-Inspired Fast Weight Programmers for Traffic-Matrix Forecasting
Kuo-Chung Peng, Jiun-Cheng Jiang, Chun-Hua Lin et al. (+3 more)
Traffic
matrices (TMs) capture network-wide origin-destination demand and are central to traffic engineering, yet accurate whole-
matrix forecasting remains challenging when prediction must be performed under the
memory, update, and training-budget constraints of online network control. This paper investigates whether compact
quantum-inspired recurrent models can provide effective TM forecasts without relying on dedicated graph,
transformer, or
diffusion modules. We adapt gated
quantum-inspired Kolmogorov-Arnold network fast-weight programmers (QKAN-FWPs) to direct multi-step Abilene TM
forecasting, where each model predicts the next 20 five-minute frames of a 144-channel origin-destination (OD)
matrix from a two-hour history. We
benchmark three QKAN placement variants against a matched-size long short-term
memory (LSTM) network, a larger LSTM, and a classical gated fast-weight programmer under a shared fixed-budget training protocol. Among the evaluated recurrent models, G-QKANFWP achieves the best pooled root-mean-square error (RMSE), while using only 22.4% of the larger LSTM. It also outperforms both the matched-size LSTM and the classical G-FWP baseline, indicating that the gain is not due to gated fast-weight framework alone. Convergence and channel-wise analyses further show that the
quantum-inspired variants obtain lower validation-loss area under the learning curve (AULC) than matched-size recurrent baselines, while G-QKANFWP and GQKAN-FWP achieve substantially more OD-channel wins. These results identify a classical slow programmer with a
quantum-inspired fast programmer as a promising accuracy-efficiency design for resource-conscious network traffic-
matrix forecasting.
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All authors Kuo-Chung Peng, Jiun-Cheng Jiang, Chun-Hua Lin, Tai-Yue Li, Nan-Yow Chen, Samuel Yen-Chi Chen
High Energy Astrophysical Phenomena
Shortterm optical variability of 4C 29.45
Aykut Özdönmez
We observed the flat-spectrum
radio quasar 4C 29.45 in the BVRI optical bands for 39 nights from February 2022 to July 2022 with the T60
telescope at TÜBİTAK National Observatory (TUG) in Turkey. In this study, we aimed to study flux, color, and spectral variability on short timescales. The object was in an active (bright) phase with an average optical R-band brightness of 14.7 mag and was variable in the BVRI bands throughout the monitoring period. We analyzed the flux variability during our observation period, and the variability amplitudes in V, R, and I bands were determined to be 220%, 208%, and 209%, respectively. Optical spectral energy distributions of 4C 29.45 were derived from the observational data of 33 nights, indicating spectral indices ranging from 1.032 to 1.573. We found modest correlations between optical light curves, and between R-band light curve and spectral indices, suggesting that the time lag ranges from several hours to days. Investigation on relation between spectral and color indices versus R-band magnitude revealed achromatic trend during the bright phase of 4C 29.45 in the first half of 2022. Our periodicity search suggested that the periodicity would be larger than 100 days, and no significant signal for periodicity was found for short timescales.
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Quantum Physics
Detector-Conditioned Source-Space Nulls and Null-Mask Loss in a Programmable Two-Slit Interferometer
Jianming Wen
Afshar's double-slit experiment probes wave–particle complementarity by placing a wire grid at the dark fringes of a downstream interference pattern while retaining an imaging basis that appears to preserve which-path information. Here we propose and analyze a time-reversed Young–Afshar configuration in which the corresponding null test is transferred from the downstream field plane to the source-label plane of a time-reversed Young interferometer. In this reciprocal geometry, a point-addressable source illuminates a double slit, while the detector remains fixed. The observed fringe is therefore not a single-shot spatial intensity pattern, but a detector-conditioned response reconstructed by scanning the source coordinate. Consequently, a null in this pattern is not a node of a freely propagating field; it is a source label for which the coherent two-slit transfer amplitude to the selected detector vanishes. A mask placed at such source-plane labels is invisible to that detector when both slits are open, yet becomes visible when either slit is opened alone. We develop the scalar Fresnel model, derive the source-space null condition, introduce a detector-conditioned null-mask loss, and examine how this loss evolves under a tunable which-path marker. The source-space visibility and path distinguishability satisfy the standard duality relation, so no violation of complementarity is implied. The essential new feature is instead a reciprocal, detector-conditioned form of complementarity: Afshar's field-space transparency is replaced by response-function transparency in a reconstructed source basis.
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Quantum Physics
Quantum Dynamic Time Warping for Multivariate Time Series Classification
Diego Alvarez-Estevez, Alejandro Mayorga-Redondo and Eduardo Mosqueira-Rey
Dynamic Time Warping (DTW) is a cornerstone for time series classification, but its reliance on Euclidean distances fails to capture latent cross-channel correlations in complex multivariate data. We propose a hybrid
Quantum Dynamic Time Warping (qDTW) architecture, replacing the classical distance metric with the parameterized geometry of a
quantum Hilbert space. Through structural ablation on
benchmarks up to $C=8$ spatial dimensions, we establish fundamental topological rules for
quantum sequence
alignment. We introduce a Unified Pre-
Embedding Adjoint Ansatz that decouples trainable
entanglement from classical data, eliminating the severe phase-scrambling and information bottlenecks inherent to traditional measurements. We demonstrate this decoupled architecture allows untrained
quantum kernels to act as highly expressive baselines, while parameterized training effectively untangles deeply overlapping hyper-dimensional data. Furthermore, we identify a strict spatial-temporal expressivity tradeoff: temporal depth (data re-uploading) is necessary for dimensionally restricted univariate
circuits, but applying it to wide multi-
qubit registers triggers chaotic frequency-spectrum explosions and representation collapse. By navigating these topological hazards, our multivariate
quantum architecture outperforms classical baselines, setting a new standard for integrating parameterized
quantum circuits with dynamic programming
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Astrophysics of Galaxies
Unraveling the Imprints of Fluctuation-dynamo on the Intracluster Medium with the SKA
Aritra Basu, Sharanya Sur, Nadia Biava et al. (+1 more)
Studying the morphology and coherence scale of the
magnetic fields in synchrotron emitting
halos of
galaxy clusters through detection of polarized synchrotron emission is important in order to understand how they distribute relativistic
plasma, their contribution to pressure balance, and how they may affect gas content in
galaxies and set up initial conditions during non-linear collapse to eventually form
galaxies in the intracluster medium (ICM). Using synthetic maps over broad-bandwidths, generated from high resolution magnetohydrodynamic simulations of fluctuation dynamo, we study the efficacy of SKA-Low and Mid in Array Assembly AA4 in our quest for detecting polarized synchrotron emission from the intracluster medium (ICM). Fluctuation dynamo action in the ICM are expected to generate ubiquitous filamentary and sheet-like
magnetic field structures. The associated synchrotron emission projected in the plane of the sky appear highly filamentary that can span hundreds of kiloparsecs. Such filaments can be robustly identified and quantified through high angular resolution ($\lesssim 1^{\prime\prime}$), sensitive observations (about $\rm 0.25\textrm{--}1\,\mu Jy\,beam^{-1}$) above about 3\,GHz, a niche for the SKA-Mid in Band\,5a. Statistical properties of polarized emission and morphological measures, such as, Minkowski functionals, can then be used to infer the
turbulence driving scales in the ICM with deep observations of
galaxy clusters using SKA-Mid. Availability of a Band\,4 receiver covering 2–4\,GHz would be a major boost in studying the polarization properties of the ICM.
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All authors Aritra Basu, Sharanya Sur, Nadia Biava, Marisa Brienza
Mesoscale and Nanoscale Physics
A real-space exceptional ring mediates an eigenframe-charge transition in a non-Hermitian skyrmion
Kejun Liu
The integer topological charge of a skyrmion is the standard example of topological protection. We ask what happens to that protection when the local generator is made non-Hermitian by polarization-selective gain or loss. The texture charge of a smoothly evolving state remains homotopy-protected under the usual fixed-boundary condition: after projective normalization, the gain/loss contribution has the Gilbert relaxation form on the target sphere. The spectral charges of the local generator behave differently. Its biorthogonal eigenframe charge is quantized while the texture avoids exceptional points. At linewidth matching, the skyrmion equator becomes a real-space exceptional ring on which the biorthogonal Bloch field diverges, and the eigenframe class jumps from +1 to 0 in a parameter-driven spectral transition. The closed contour relies on constant splitting along the equator, or an equivalent design constraint; a partial or amplitude-anisotropic realization instead leaves isolated real-space exceptional points. We use an operational Jones parametrization of an isolated polarization doublet and give a Stokes-
tomography reconstruction of the left-right frame. The result identifies a spatially resolved exceptional contour that mediates an integer transition of a real-space eigenframe charge.
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Disordered Systems and Neural Networks
Mingpu Jiang and Jianhui Zhou
The
quantum geometric tensor is a fundamental property of
quantum states, with broad applications in condensed matter physics, topological phases, and
quantum phase transitions. The
eigenvalues characterize the scale, anisotropy, and effective rank of random
quantum geometry, going beyond scalar quantities such as the trace. Here we study the
eigenvalue statistics of the
quantum geometric tensor in finite-dimensional parameter-dependent random
Hamiltonians. We obtain exact analytical results for the first two nontrivial cases, $N=2$ and $N=3$, with $N=3$ already showing genuine shape fluctuations. We further propose a finite-$N$, arbitrary-$D$ description of QGT
eigenvalue statistics and verify it by numerical simulations. Our results provide exact
benchmarks and a practical framework for random
quantum geometry in finite-dimensional disordered and chaotic systems.
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Quantum Physics · Cross-listed from cs.LO
The quantum instrument monad
Tobias Fritz
Monads are a ubiquitous structure in functional programming used for modelling computational effects. For example, the state monad models the effect of a computation interacting with a
memory system. Here we introduce the
quantum instrument monad $\mathcal{I}_\mathcal{A}$, which models the effect of a computation interacting with a
quantum system with
algebra of observables $\mathcal{A}$. It can be thought of as a noncommutative generalization of the state monad. We construct this
quantum instrument monad in two versions: a finitary version on the category of sets and a measure-theoretic version on the category of measurable spaces (the latter under the assumption that $\mathcal{A}$ is a type I von Neumann
algebra with separable predual). Both versions are strong monads. The construction of the measure-theoretic version is based on a new notion of integral of a
quantum-operation-valued function against a state-valued measure.
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High Energy Physics (Phenomenology)
Bootstrapping two-loop six-gluon amplitudes in QCD
Sérgio Carrôlo, Dmitry Chicherin, Johannes M. Henn et al. (+2 more)
The maximally transcendental, or most complicated, terms of gauge-theory scattering amplitudes have long been singled out, following Lipatov and collaborators, as those parts of a QCD amplitude that most closely mirror maximally supersymmetric Yang–Mills theory. We report on a programme that turns this observation into a practical computational tool. We show that the rational prefactors multiplying the highest-weight special functions of planar QCD amplitudes are governed by four-dimensional leading singularities, which can be classified and evaluated using on-shell diagrams. The resulting prefactors are manifestly conformally invariant and admit compact spinor-helicity expressions that hold for arbitrary multiplicity. Combining this input with the recently established two-loop six-particle function space, we set up a symbol bootstrap and determine, for the first time, the maximal-weight symbol of the planar two-loop six-
gluon amplitude in massless QCD, first for the ${-}{-}{+}{+}{+}{+}$ helicity configuration and subsequently for all MHV configurations. The answer is fixed uniquely by physical consistency conditions, requires a reduced alphabet of only $137$ symbol letters, and yields as a byproduct previously unknown two-loop triple-collinear and double-soft splitting functions. We summarise the method and the results, and outline the directions they open up.
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All authors Sérgio Carrôlo, Dmitry Chicherin, Johannes M. Henn, Qinglin Yang, Yang Zhang
General Relativity and Quantum Cosmology
New interpretation of the Minkowski limit of $R^2$ gravity
Valerio Faraoni, Luca Gallerani, Alain Maltais-Gosselin et al. (+2 more)
It is well-established that the Minkowski limit of pure $f(R)=R^2$
gravity breaks down, unlike that of full Starobinsky theory $f(R)=R+\alpha R^2$. We provide a novel interpretation of this phenomenon using the recent thermal analogy between scalar-tensor
gravity and Eckart's relativistic dissipative fluids. In this framework, we show that approaching the Minkowski background corresponds to a diverging effective “gravitational temperature” along certain non-stationary FLRW trajectories, while the gravitational temperature remains identically zero along the exact de Sitter family. This perspective naturally rephrases the strong coupling problem as a thermal singularity, demonstrating that $R^2$
gravity departs infinitely far from General Relativity rather than recovering it.
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All authors Valerio Faraoni, Luca Gallerani, Alain Maltais-Gosselin, Santiago Novoa-Cattivelli, Uri Gorman
High Energy Astrophysical Phenomena
A pulsar escaping an ancient open cluster via tidal stripping
Lei Zhang, Xiaoting Fu, Di Li et al. (+21 more)
Open clusters are the primary birthplaces of
stars in the Milky Way disk, yet their
neutron star progeny are rarely found within them, presumably due to
supernova-induced kicks that eject them at birth. Here we report the arcsec-level localization of the
pulsar PSR J1921+3745 to the
tidal tail of NGC 6791, one of the oldest and most massive open clusters. Our N-body simulation shows that more than 95% of
neutron stars formed in such clusters have been ejected. This
pulsar's location in the
tidal tail indicates it was retained for billions of years before being stripped by
Galactic tides. This long-term retention requires low natal kicks, consistent with formation via electron-capture
supernova. Our findings capture a rare snapshot of a
neutron star transitioning into the
Galactic field, identifying
tidal stripping of ancient clusters as a verified source of the
Galactic neutron star population.
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All authors Lei Zhang, Xiaoting Fu, Di Li, Emma Carli, Long Wang, Jiaqi Zhao, Craig O. Heinke, Emanuele Dalessandro, Yang Chen, Angela Bragaglia, Duncan R. Lorimer, Ewan D. Barr, Sarah Buchner, Shi Dai, Zhiyu Zhang, Erbil Gügercinoğlu, Alessandro Ridolfi, Jie Zhang, Meng Guo, Mengmeng Ni, Jiale Hu, Yi Feng, Pei Wang, Qijun Zhi
General Relativity and Quantum Cosmology
The shadow radius lower bound is more robust than the photon sphere radius lower bound in $n$-dimensional Einstein gravity
Jiaqi Fu and Yong Song
The
photon sphere and the black hole shadow are two closely related
geometric features of strong-field spacetimes: the
photon sphere is a hypersurface foliated by circular null geodesics, while the shadow boundary is determined by the critical impact parameter for null-geodesic capture. For static, spherically symmetric, asymptotically flat black holes in $n$-dimensional ($n\ge4$) Einstein
gravity with anisotropic matter, we derive lower bounds on the shadow radius and the
photon sphere radius and compare their matter assumptions. Assuming that an auxiliary function $\Xi(r)$ satisfies $-\rho\le\Xi\le p_r$ and $(r^2\Xi)'\ge0$ between the horizon and the
photon sphere under consideration, we establish $r_\gamma\ge[(n-1)/2]^{1/(n-3)}r_H$, where $r_H$ is the event horizon radius. Writing the shadow radius as $r_{\mathrm{sh}}=[\max_{r>r_H}U(r)]^{-1/2}$, where $U(r)$ is the null effective potential, we obtain $r_{\mathrm{sh}}/r_H\ge[(n-1)/2]^{1/(n-3)}\sqrt{(n-1)/(n-3)}$ using only $\rho\ge0$ and $\rho+p_r\ge0$, both implied by the weak energy condition (WEC). This shadow bound holds irrespective of the number of
photon spheres and does not require the additional matter conditions used in the
photon sphere lower-bound proofs. In this sense, the lower bound on the shadow radius is more robust than that on the
photon sphere radius. A four-dimensional configuration satisfying the WEC has a single exterior
photon sphere and obeys the shadow bound while violating the
photon sphere lower-bound inequality, demonstrating this distinction even when both radii are associated with the same
photon sphere. Both lower bounds are saturated by the Schwarzschild–Tangherlini solution. In Appendix~A, we also derive the mass-dependent upper bounds under the WEC, the strong energy condition, and suitable asymptotic decay assumptions.
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Quantum Physics
Single-sideband-interference twin-field quantum key distribution without global phase locking
Xingjian Li, Bingkun Wang, Jianyong Hu et al. (+10 more)
Twin-field
quantum key distribution (TF QKD) can overcome the fundamental rate loss limit of repeaterless
quantum links, but its practical deployment has long been hindered by the requirement of global phase locking between two independent
lasers. By revisiting the fundamental principles of optical interference, this work reveals that interference in TF QKD inherently relies only on the instantaneous phase
alignment of two independent optical pulses at the moment they temporally overlap, rather than on continuous global phase synchronization. Guided by this insight, we propose and demonstrate a single-sideband-interference TF-QKD protocol that eliminates global phase locking. Each user employs an IQ modulator to generate a weak single sideband as the
quantum signal, while the intrinsically phase-correlated optical carrier propagates as a real-time phase reference. Carrier interference at the receiver enables real-time phase extraction and feedback compensation for the sidebands. Unlike prior no phase locking approaches requiring second- or microsecond-level coherence, in principle, our scheme reduces this requirement to nanoseconds. We achieve 98% interference visibility over 100.8 km fibre and secure key rates surpassing the PLOB bound in the high-loss regime, providing a simpler route towards practical long-distance
quantum communication networks.
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All authors Xingjian Li, Bingkun Wang, Jianyong Hu, Jianqiang Liu, Shuxiao Wu, Guosheng Feng, Zhixing Qiao, Changgang Yang, Ruiyun Chen, Chengbing Qin, Guofeng Zhang, Liantuan Xiao, Suotang Jia
Mesoscale and Nanoscale Physics
Non-Newtonian two-dimensional electron fluid in magnetic field
P. S. Alekseev and M. A. Semina
We develop a theory of the non-Newtonian regime of non-linear hydrodynamic magnetotransport of a two-dimensional (2D) viscous electron fluid controlled by the local Joule heating. In this mechanism, the electron shear viscosity in
magnetic field becomes a non-monotonic function of the gradient of the hydrodynamic velocity due to the flow-induced increase of the electron temperature. We derive and solve the corresponding non-linear hydrodynamic equations for a velocity profile in a Poiseuille-like flow geometry. We demonstrate that the calculated magnetoresistance of such flow well explains the differential magnetoresistance observed for 2D electrons in various samples of ultra-high-quality GaAs
quantum wells at high currents. We conclude that the non-linear regime of 2D electron fluid flows is such systems is realized via formation of a 2D non-Newtonian electron fluid, related to non-linearity in viscosity, but not via convective “kinematic-induced” effects, as it takes place in ordinary uncharged fluids.
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Quantum Physics
Industry-ready spin-photon interfaces for hybrid photonic quantum computing
Hêlio Huet, Hubert Lam, Thibaut Pollet et al. (+45 more)
Hybrid photonic
quantum computers, combining stationary matter
qubits and flying photonic
qubits, offer an intrinsically networked and resource-efficient route to large-scale, error-corrected
quantum computation. Their core components are cavity-coupled matter
qubits that act as light–matter interfaces, enabling: high-efficiency on-demand single-
photon generation, stable near-unity
photon indistinguishability and
spin–multi-
photon entanglement.
Semiconductor quantum dots in microcavities are a leading platform for realizing such devices. Yet reaching the performance, reproducibility and
spin-coherence thresholds for large-scale error correction remains a major challenge requiring industrial fabrication and control. Here we report thousands of monolithic
semiconductor quantum-dot devices fabricated using a III–V pilot production-line process compatible with large-scale deployment. Systematic control of source parameters yields state-of-the-art efficiency and supports a path to optical losses below fault-tolerance thresholds. Using field-quadrature state reconstruction as a stringent joint test of efficiency and indistinguishability, we observe near-unity
photon quantum purity stable over tens of minutes and a record single-
photon Wigner-function negativity. We further demonstrate seven-partite
spin–multi-
photon entanglement and
spin coherence extendable to microsecond timescales in the low-
magnetic-field regime. Finally,
photons from distant sources are as indistinguishable as
photons emitted successively by a single source. These results establish foundry-compatible III–V
quantum dots as a scalable platform for hybrid photonic
quantum computing.
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All authors Hêlio Huet, Hubert Lam, Thibaut Pollet, Petr Steindl, Alice Bernard, Albert Adiyatullin, Petr Stepanov, William Hease, Victor Guilloux, Nico Margaria, Joris Verstraten, Raksha Singla, Samuel T. Mister, Anton Pishchagin, Lara Couronné, Samuel Huber, David Sebastian, Duc Duy Tran, Thi Hao Nhi Nguyen, Thi Phuong Do, Joseph Sulpizio, Yann Portella, Kiarn T. Laverick, Thinhinane Bennour, Tomas Alexandre De Sousa, Davide Stefani, Mathias Pont, Maxime Descampeaux, Bianca Scaparra, Martin A. Jacobsen, Klaus D. Jöns, Rinaldo Trotta, Aristide Lemaître, Martina Morassi, Olivier Krebs, Loïc Lanco, Niels Gregersen, Alexia Auffèves, Maria Maffei, Shane Mansfield, Jean Senellart, Thomas Volz, Viviana Villafañe, Stephen C. Wein, Dario A. Fioretto, Sebastien Boissier, Thi Huong Au, Pascale Senellart
High Energy Astrophysical Phenomena
Fe K{\alpha} equivalent-width mapping with 3D radiative transfer calculation: A general model and application to the RS Canum Venaticorum-type stars with XRISM/Resolve
Shun Inoue, Masahiro Tsujimoto, Takayuki Hayashi et al. (+4 more)
The Fe K $\alpha$ fluorescence line at 6.4 keV has long been used to probe the relative geometry between photoionizing X-ray sources and surrounding cold material in a wide range of astrophysical systems. With the advent of the X-ray microcalorimeter XRISM/Resolve, Fe K $\alpha$ lines with equivalent widths down to $\sim 5$ eV-previously inaccessible-are now detectable, and even non-detections can place upper limits of a few eV, making non-detections themselves valuable for constraining the geometry. Considering that Fe K $\alpha$-based
geometric diagnostics are entering a new stage in the microcalorimeter era, we present Fe K $\alpha$ equivalent-width maps computed with the three-dimensional Monte Carlo radiative-transfer code SKIRT for a generalized configuration consisting of a spherical reflector of radius $R_{*}$ and a point source located at a height $h$ above the surface. The equivalent-width maps exhibit two characteristic features: (1) an increase toward the center of the projected surface of the sphere; and (2) an overall decrease with increasing $h/R_{*}$. The key point is that we confirm these features for equivalent widths of $< 40$ eV, a regime that has become accessible for the first time thanks to the improved detection threshold from $\sim 50$ eV with Chandra/HETG to $\sim 5$ eV with XRISM/Resolve. As an illustrative application, we compare the maps with XRISM/Resolve spectra of three RS Canum Venaticorum-type
stars (GT Muscae, $\sigma$ Geminorum, and HR 1099) and constrain the locations of the
flare loop and coronal bright points in these systems. Because the maps are constructed for a highly generalized point-source–spherical-reflector geometry, they are readily applicable to many other objects, including X-ray binaries and cataclysmic variables.
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All authors Shun Inoue, Masahiro Tsujimoto, Takayuki Hayashi, Teruaki Enoto, Yuta Notsu, Hiroyuki Uchida, Miki Kurihara