Quantum Physics
Phase Retrieval in $\mathbb C^4$ Requires Exactly Eleven Measurements
Meng Huang and Jihun Kim
Determining the minimal number of intensity measurements required for phase
retrieval in $\mathbb{C}^4$ has been a long-standing open problem. Prior to this work, the best-known results implied that this minimum was either $10$ or $11$. In this paper, we leverage characteristic classes and
cohomology groups from differential
topology to prove that no family of $10$ vectors in $\mathbb{C}^4$ possesses the phase
retrieval property. Combining our lower bound with Vinzant's explicit eleven-vector construction establishes that the exact minimum is $11$. Our result yields a significant consequence for pure state
quantum tomography, namely, a rank-one POVM on $\mathbb{C}^4$ requires exactly $11$ elements to be informationally complete for pure states. This further implies that three orthonormal bases are insufficient to uniquely distinguish all pure states in $\mathbb{C}^4$. Because four orthonormal bases are already known to be sufficient, we conclude that exactly four bases are required, thereby completely resolving the problem left in [C. Carmeli, T. Heinosaari, J. Schultz, A. Toigo, Eur. Phys. J. D].
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Quantum Physics
Jun-Jie Jiang, Jin-Di Cao, Yu-Fei Zhang et al. (+2 more)
We investigate the charging dynamics and thermodynamic performance of a wireless
quantum battery system mediated by a common structured bosonic environment. By employing a unified resource-theoretic analysis, we elucidate the distinct roles of non-Markovian
memory effects and coupling
symmetry in regulating energy transfer. In the Markovian weak-coupling regime, we identify a transformative mechanism where the dynamic reconstruction of $l_1$-norm coherence compensates for the monotonic decay of first-order coherence to sustain energy transport. Conversely, the non-Markovian strong-coupling regime facilitates a cooperative resonance, characterized by the synchronized oscillation of
entanglement and stored energy induced by environmental backflow. Furthermore, we reveal that coupling
symmetry acts as a critical control parameter: while asymmetric coupling favoring the battery optimizes energy gain in memoryless environments, symmetric coupling under strong interactions unlocks a dark-state protection mechanism, effectively trapping energy within a decoherence-free subspace. Finally, a thermodynamic analysis based on ergotropy demonstrates that first-order coherence establishes the activation threshold for incoherent work, whereas $l_1$-norm coherence serves as the explicit fuel for coherent work extraction. These findings provide a refined theoretical framework for engineering environment-assisted
quantum energy storage devices.
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All authors Jun-Jie Jiang, Jin-Di Cao, Yu-Fei Zhang, Meng-Long Song, Dong Wang
Materials Science
Optimization of magneto-electric properties in Lead-free (x)Co1.2Ti0.2Fe1.6O4 - (100-x)BaTiO3 based composites
Rajeev Dwivedi, Samanway Mohanta, Ashutosh Anand et al. (+7 more)
This work presents a systematic study of lead-free multiferroic composites of (x)Co1.2Ti0.2Fe1.6O4 - (100-x)BaTiO3 (x = 10, 20, 30), which were synthesized by a solid-state reaction method to investigate the effects of composition and sintering temperature on their structural , electrical,
magnetic, and magnetoelectric (ME) properties. X-ray diffraction along with Rietveld refinement confirms the coexistence of tetragonal BaTiO3 (BTO) and cubic spinel Co1.2Ti0.2Fe1.6O4 (CTFO) phases. Microstructural analysis shows that densification and grain growth are better at higher sintering temperatures, leading to better coupling between the two phases. Dielectric and ferroelectric studies indicate lossy polarization-electric field (P-E) behaviour due to leakage from the conductive phase, while
magnetic properties show increased magnetization with increasing ferrite content. All composites exhibit ME coefficients, which depend on the composition and sintering conditions; the highest ME coefficient (~1.28 mV/cm.Oe) was observed for the 30CTFO - 70BTO composite sintered at 1200 {\deg}C. This improvement is due to the optimal balance between magnetostrictive and piezoelectric responses and improved interfacial strain transfer. These results demonstrate that simultaneous optimization of dopant-modified composition and sintering conditions is essential for achieving improved magnetoelectric coupling in bulk multiferroic composites. Moreover, the results demonstrate the potential of lead-free composites for multifunctional device applications in next-generation, low-power technologies, including high-density non-volatile
memory (e.g. FeRAM/MRAM),
magnetic field sensors, spintronic devices, and actuators.
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All authors Rajeev Dwivedi, Samanway Mohanta, Ashutosh Anand, Abhinash Tripathy, Najnin Bano, Dharmendra Kumar, Hemant Singh, R. Venkatesh, Sachin Gupta, Dinesh Kumar Shukla
Optics
Multi-mode fiber enabled multi-wavelength optical trapping and dynamic manipulation
Yikun Shen, Chuangye Zhang, Yuquan Zhang et al. (+7 more)
Optical fiber tweezers offer distinct advantages for long-distance manipulation, compact integration, and minimally invasive operation in biological environments. However, most optical fiber tweezers rely on single-mode fibers (SMFs), which are constrained by limited optical mode diversity and reduced control flexibility. Although multi-mode fibers (MMFs) support a wider spectrum of propagation modes, their inherent mixed guided modes with low coherence become a long-standing limitation for the design of focused trapping configurations. To address these limitations, we propose and experimentally validate a fully MMF-based optical tweezer system integrated with a micro-lens structure fabricated on the fiber facet, enabling stable optical trapping across multiple wavelengths and dynamic manipulation of trapped
cells. Employing 532 nm continuous-wave and 800 nm femtosecond
lasers, we demonstrate that both light sources can generate tightly focused optical spots through the micro-lens with a high numerical aperture (NA>0.7), achieving robust trapping and axial dynamic manipulation of
cells. Compared with conventional SMF-based tweezers, this approach leverages the broadband and multi-mode properties of MMFs, allows for wavelength-flexible and dynamically adjustable trapping of
cells, and paves the way for lab-on-fiber biophotonic platforms with potential applications such as interventional manipulation,
cell sorting, and cellular fluorescence analysis.
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All authors Yikun Shen, Chuangye Zhang, Yuquan Zhang, Jiahui Pan, Siwei Chen, Hongyang Xu, Yixuan Chen, Qi Jin, Xiaocong Yuan, Changjun Min
High Energy Physics (Experiment)
Search for $\textit{tH}$ production in the $ H \to \tau\tau$ decay mode, and a combination with other searches, using $\textit{pp}$ collisions at 13 TeV and 13.6 TeV with the ATLAS detector
ATLAS Collaboration
A search for the production of a
Higgs boson in association with a single top
quark in multi-
lepton final states including $\tau$-
leptons is presented, using an integrated luminosity of $140\,\text{fb}^{-1}$ of
proton-
proton collision data at a centre-of-mass energy of $\sqrt{s} = 13\,\text{TeV}$ collected by the ATLAS detector at the LHC. The analysis targets the $H \to \tau\tau$ decay, where at least one $\tau$-
lepton decays hadronically, to indicate the presence of the
Higgs boson. No significant excess over the expected background is observed, and an observed (expected) upper limit at the 95% confidence level on the signal strength is set at 8.6 (9.3) times the Standard Model prediction. This measurement is combined with previous publications of the ATLAS Collaboration targeting the same production process but in different final states, using $140\,\text{fb}^{-1}$ of
proton-
proton collision data at $\sqrt{s} = 13\,\text{TeV}$ and $164\,\text{fb}^{-1}$ at $13.6\,\text{TeV}$. The combined measurement of the signal strength yields $\mu_{tH} = 3.3^{+1.7}_{-1.5} = 3.3 \pm 1.2\,(\text{stat.})^{+1.1}_{-1.0}\,(\text{sys.})$ times the Standard Model expectation, corresponding to an observed (expected) $\textit{tH}$ significance of 2.3 (0.8) standard deviations. The combined observed (expected) upper limit at the 95% confidence level on the signal strength is set at 6.1 (2.7) times the Standard Model prediction. This combination represents the most precise measurement of $tH$ production to date.
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General Relativity and Quantum Cosmology
Constrained thermodynamics and geodesic observables of an effective non-commutative Kerr-like black hole
H. Hassanabadi, L. A. López, N. Bretón et al. (+2 more)
We investigate the horizon structure, constrained thermodynamics, and geodesic properties of an effective Kerr-like black hole in a non-commutative background. Deformation modifies the radial geometry through a mass-dependent charge-like contribution, while preserving the separability of the geodesic equations. We determine the conditions for horizon existence, identify the extremal zero-temperature configuration, and analyze the stationary-limit surfaces and the ergoregion. Special
attention is paid to the thermodynamic interpretation of the model, where the
geometric Hawking quantities are distinguished from the conjugate variables associated with the constrained state space at fixed non-commutative deformation parameter. The canonical and grand-canonical heat capacities are derived to characterize their ensemble-dependent local thermal behavior. We also obtain the spherical
photon region, equatorial light rings, and shadow boundary, showing that the deformation shifts the characteristic
photon orbits inwards and reduces the overall size of the shadow. Timelike circular motion is studied through the innermost stable circular orbit, where non-commutative correction produces an inward shift of both the prograde and retrograde branches. Finally, invariant
photon frequency shifts are obtained by treating the emitter's orbital direction and the
photon's tangential emission direction as independent physical choices.
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All authors H. Hassanabadi, L. A. López, N. Bretón, L. M. Nieto, S. Zare
Materials Science
Unconventional and Fragile Magnetic Exciton in a van der Waals Quantum Magnet
Kai-Xuan Zhang, Min Zhang, Minjae Kim et al. (+25 more)
The recently discovered
magnetic exciton in the van der Waals (vdW) antiferromagnet NiPS3 exemplifies these phenomena, exhibiting several distinctive characteristics. Despite extensive investigation, much of its physics remains unresolved, with key questions about why the NiPS3
magnetic exciton is so sharp and optically bright despite the nominally
spin-forbidden transition, posing significant challenges to a proper understanding and practical manipulation of the
exciton. An urgent question is to what extent it is due to chemical disorder,
magnetic weakening,
lattice modification, or intrinsic instability of the bright
exciton itself: answers to which will put stringent constraints on possible theoretical models. Here we address these questions using hydrostatic pressure as a clean, continuous, reversible, and in-situ tuning parameter. We find that the sharp photoluminescence peak is drastically suppressed by as little as 0.4 GPa and completely quenched by 1.5 GPa, with demonstrating its reversibility. Crucially, this bright-to-dark conversion occurs without
magnetic, crystallographic, or electronic reconstruction despite an increase in the Neel temperature, as established by Raman, X-ray absorption,
nuclear magnetic resonance spectroscopy, and first-principles many-body calculations. Our results demonstrate that the optical brightness of the
magnetic exciton is independent of chemical disorder,
lattice expansion, and weakening of
magnetic order, indicating that a higher-order correlated mechanism governs the bright
exciton. We further propose experimentally constrained microscopic scenarios involving
exciton pairing,
crystal-field-controlled
spin-orbit mixing, and
symmetry breaking, providing a framework for future tests of entangled
magnetic exciton in correlated
quantum magnets.
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All authors Kai-Xuan Zhang, Min Zhang, Minjae Kim, Yong-Hyun Kim, Junghyun Kim, Heejun Yang, Pyeongjae Park, Chaebin Kim, Mangesh Diware, Junik Hwang, Youjin Lee, Byeong-Gwan Cho, Hyeong-Do Kim, Tae-Yeong Koo, Chunhua Chen, Mingtao Li, Xujie Lü, Wenge Yang, Kee-Hoon Kim, Seung-Ho Baek, Hyeonsik Cheong, Sung-Keun Lee, Beom Hyun Kim, Christopher Lane, Jian-Xin Zhu, Zhaorong Yang, Young-Woo Son, Je-Geun Park
Materials Science
A Universal Crystal-Field Design Principle for Orbital-Order-Driven Altermagnetism
Shantanu Pathak and Saswata Bhattacharya
Altermagnets combine collinear
antiferromagnetic order with nonrelativistic
spin splitting, enabling spintronic functionalities without relying on
spin–orbit coupling. While staggered orbital ordering has recently emerged as an alternative route to altermagnetism, its generality has remained unexplored. Here, we establish a universal
crystal-field design principle for orbital-order-driven altermagnetism. We show that structural relaxation consistently reconstructs the
crystal-field landscape, activating a common $d_{xz}/d_{yz}$ orbital
manifold that drives spontaneous staggered orbital ordering and robust $d$-wave nonrelativistic
spin splitting across transition-metal compounds spanning electron fillings from $d^1$ to $d^7$. By introducing a unified
symmetry framework based on layer-dependent
magnetic and orbital order parameters, we demonstrate how interlayer stacking determines whether the system realizes a bulk altermagnetic state or a globally compensated antialtermagnetic phase. Furthermore, we reveal that this
symmetry-protected
spin-split texture gives rise to highly anisotropic
spin-polarized conductivities. Our results establish
crystal-field engineering as a predictive design strategy for discovering and engineering orbital-order-driven altermagnets.
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High Energy Astrophysical Phenomena
Distinct Jet Properties in the X-Ray-Obscured State of GRS 1915+105
Xi Yan, Lang Cui, Sergei Trushkin et al. (+6 more)
GRS 1915+105 has remained in an X-ray-obscured state since its transition from a long-lasting unobscured state in 2019. We report on 6.7-GHz East Asia VLBI Network observations of GRS 1915+105 obtained during strong
radio flares detected at 2.3–11.2 GHz with the RATAN-600
radio telescope in 2025. Our images reveal two contrasting jet morphologies. The first epoch, associated with a
flare evolving from an optically thick to an optically thin spectrum, shows a bright
radio core accompanied by an extended jet structure. By contrast, the second epoch, observed near the peak of another
flare displaying optically thin emission at lower frequencies, is dominated by two bright, symmetric, well-separated jet blobs and shows no detectable
radio core. If these jets exhibited the apparent superluminal motions commonly observed prior to 2019, measurable angular shifts would be expected over the five-hour observations. However, no significant jet motion is detected. Combined with our derived jet speed of $\beta\Gamma \lesssim 0.40$, these results suggest that the jets launched during the current obscured state are slower than the relativistic jets ($\beta\Gamma \gtrsim 1$) observed earlier during the unobscured state. Together with the recently reported large variations in jet orientation, our findings in GRS 1915+105 provide robust support for the emerging paradigm that X-ray binary jets launched in obscured and unobscured states likely exhibit distinct propagation properties.
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All authors Xi Yan, Lang Cui, Sergei Trushkin, Shuangjing Xu, Wu Jiang, Zhen Yan, Sándor Frey, Timur Mufakharov, Ruchika Dhaka
Quantum Physics
Quadruply Bonded Mo2 Molecules: An Innate Emitter-Resonator Quantum System in Free Space
Miao Meng, Ying Ning Tan, Zi Cong He et al. (+5 more)
In recent decades, significant progress has been made in constructing and studying individual
quantum systems based on two level atoms (molecules) and
photons. Here we demonstrate that the quadruply bonded Mo2 unit, with a MoMo bond distance as short as 2.1A, functions as an innate emitter resonator molecular
quantum system capable of trapping visible light
photons between the two molybdenum atoms under ambient conditions, thereby generating an intense quantized local electromagnetic field with an extremely small mode volume. The resonance fluorescence spectra of three Mo2 complexes indicate that the intermetallic Mo-Mo charge transfer transition is coherently coupled to the local scattering field, exhibiting
vacuum Rabi splitting and Mollow triplets. Resonant coupling of single molecules and N-molecule ensembles to the scattered light through sideband excitation produces a sequence of discrete optical modes spanning a broad wavelength range, with polaritonic transitions identical to those observed in Ni2 based systems. These results establish the Mo2 molecule as an independent emitter resonator integrated
quantum system that enables
quantum optical experiments in free space using conventional spectroscopic instrumentation. This work extends
quantum electrodynamics into molecular science, providing new insights into metal metal bonding, molecular physics, and light matter interactions.
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All authors Miao Meng, Ying Ning Tan, Zi Cong He, Zi Hao Zhong, Jia Zhou, Yu Li Zhou, Guang Yuan Zhu, Chun Y. Liu
Strongly Correlated Electrons
Iterative minimization in reduced density matrix functional theory for periodic systems
Kai Luo, Jingang Han, Peize Lin et al. (+3 more)
Reduced density
matrix functional theory (RDMFT) offers a route beyond Kohn-Sham density functional theory for strongly correlated systems, yet practical calculations for periodic solids are still out of reach. We formulate RDMFT for extended systems in a basis-independent way and present a planewave implementation using iterative minimization for periodic solids, evaluating nonlocal exchange-correlation functionals through the existing adaptive compressed exchange machinery. Natural occupations are optimized under N-representability constraints with a spectral projected gradient (SPG) method or an first-order explicit-by-implicit (EBI) map, while natural orbitals are updated by Riemannian optimization on the complex Stiefel
manifolds.
Benchmarks on typical systems of \ce{H2}, silicon, and sodium with the Hartree-Fock functional show that SPG reproduces converged hybrid references, whereas EBI can stall when occupations approach $0$ or $1$. With the power and Müller functionals, SPG yields lower energies and more stable convergence than EBI. Applications to fractionally charged \ce{LiH}, dissociating \ce{H2} and \ce{N2} molecules, and equation of state of silicon show that the
algorithm presented in this implementation is reliable and robust.
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All authors Kai Luo, Jingang Han, Peize Lin, Daye Zheng, Mohan Chen, Xinguo Ren
Astrophysics of Galaxies
The X-ray-Weak Tail of the Quasar Population: Physical Properties and Redshift Evolution of Variability-Selected AGN in eFEDS
P. Arévalo, J. Buchner, M. Salvato et al. (+10 more)
(abridged) Aims: To characterize variability-selected AGN candidates within the eROSITA Final Equatorial-Depth Survey (eFEDS), leveraging the synergy between optical variability and deep X-ray observations by SRG (Spectrum Roentgen Gamma)/eROSITA, to compare the physical properties of AGN populations selected through complementary methods. Methods: We used a sample of AGN candidates selected via optical variability by Arévalo et al. and cross-match it to the X-ray selected eFEDS AGN sample. Spectroscopic characterizations are obtained for the matched samples from the Dark Energy Spectroscopic Instrument public data products. Results: We find a high classification purity with 98% candidates confirmed as broad-line AGN/QSOs. We identify a significant population (25%) that lack X-ray counterparts (X-U) in the eFEDS survey. We find that the X-D and X-U samples exhibit distinct physical properties and
redshift distributions. The X-U sample peaks at $z = 2$ while the X-D sample at $z =1$, with nearly half of the variability-selected AGN at $z > 2.5$ remaining undetected in X-rays. This missing fraction can be attributed to K-correction effects and SED
evolution with luminosity, mainly resulting in high
accretion rate objects falling out of the X-D sample at higher
redshifts. X-ray variability accounts for a part of the missing fraction but its dependence with
redshift is less clear. Ensemble spectral analysis reveals that X-D sources have steeper optical continua and stronger broad emission lines than their X-U counterparts, while the forbidden and semi-forbidden lines have equal EWs in both samples. Finally, broad absorption line (BAL) features are found almost exclusively in the X-U population. This "missing" X-ray population must be accounted for when extrapolating X-ray-selected AGN to the broader Type I population and could impact
cosmic estimates of massive black hole growth.
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All authors P. Arévalo, J. Buchner, M. Salvato, P. Sánchez-Sáez, F. Bauer, M.L. Martínez-Aldama, D. Tubín-Arenas, J. Cerón-Meneses, R. Pucha, P. Lira, A. Merloni, M. Mezcua, M. Krumpe
High Energy Physics (Theory)
Non-relativistic Floquet Conformal Field Theory
Diptarka Das, Sumit R. Das, Arnab Kundu et al. (+1 more)
We develop a formalism for studying Floquet dynamics for systems with non-relativistic conformal invariance in d spatial dimensions. Our analysis indicates the existence of two dynamical phases,
hyperbolic and
elliptic, separated by a
parabolic transition surface. We demonstrate this by studying the fidelity of the driven state and the expectation value of a conformal generator in the many body ground state during the drive. Stroboscopically, they behave exponentially in the
hyperbolic phase, show oscillatory behavior in the
elliptic phase, and exhibit power-law on the transition surface. Our analysis is completely universal and can be directly applied to several systems including trapped
fermions near unitarity and resonant anyons. The former can provide experimental signatures of these dynamical phases. We also comment on a
holographic perspective of such driven non-relativistic CFTs and demonstrate that the
hyperbolic phase is associated with a timelike stationary-limit surface, such as an ergosphere, in the bulk, while the
parabolic phase corresponds to an extremal Killing horizon.
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All authors Diptarka Das, Sumit R. Das, Arnab Kundu, Krishnendu Sengupta
General Relativity and Quantum Cosmology · Cross-listed from math.DG
Volume Stability for Hyperbolic Manifolds and Applications to General Relativity
Puskar Mondal and Shing-Tung Yau
We prove a sharp volume-stability
theorem for closed
hyperbolic three-
manifolds. Let \((M,h)\) be closed
hyperbolic with \(\operatorname{Ric}_h=-2h\), and let \(g_i\) be smooth metrics on \(M\) satisfying $R(g_i)\geq -6, \operatorname{Vol}_{g_i}(M)\longrightarrow \operatorname{Vol}_h(M)$. After passing to a subsequence, there exist \(Z_i\subset M\), smooth domains \(K_i\subset M\), and diffeomorphisms $\psi_i:K_i\longrightarrow M\setminus Z_i $ such that $\operatorname{Vol}_{g_i}(Z_i)\longrightarrow0, \operatorname{Vol}_h(M\setminus K_i)\longrightarrow0, $ and $ \|\psi_i^*g_i-h\|_{C^0(K_i,h)}\longrightarrow0. $ Thus near-equality in the sharp
hyperbolic volume bound forces tensorial \(C^0\)-convergence to the
hyperbolic metric outside regions of vanishing volume. As an application, we establish stability of the Fischer–Moncrief reduced
Hamiltonian at the Lorentz-cone ground state: after CMC normalization, near-minimizing compact
vacuum data in the
hyperbolic topological class converge, modulo sets of vanishing volume, to the
hyperbolic Lorentz-cone geometry in tensorial \(C^0\). This provides a rigorous volume-dominance formulation of the Fischer–Moncrief asymptotic picture.
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Instrumentation and Methods for Astrophysics
Proof of Concept Measurements of Laterally Graded Multilayers for Soft X-ray Spectropolarimetry
Sarah Heine, Herman L. Marshall, Alan Garner et al. (+2 more)
This work describes proof of concept measurements for a soft X-ray spectropolarimeter that utilizes laterally graded multilayer mirrors within a grating spectrometer. The work tests two multilayers: a Chromium-Scandium multilayer designed to be utilized at Brewster's angle in the 200-400 eV range and a Tungsten Boron Carbide mirror designed to reflect X-rays at 30 degrees incidence in the 500-850 eV range. We present measurements of monochromatic, polarized light reflecting off of these multilayers over a range of polarization angles, demonstrating the expected modulation of signal with respect to incident polarization angle
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All authors Sarah Heine, Herman L. Marshall, Alan Garner, Eric Gulllikson, Nithya Kothnur
Astrophysics of Galaxies
Galactic HII regions in LAMOST Medium-Resolution Spectroscopic Survey of Nebulae
Yunning Zhao, Wei Zhang, Lin Ma et al. (+10 more)
Based on LAMOST Medium-Resolution Spectroscopic Survey of Nebulae (MRS-N) data and WISE
Galactic HII region catalog, we construct a sample of 280
Galactic HII regions and candidates in the Outer
Galaxy (80$^{\circ}$ $\lesssim$ l $\lesssim$ 220$^{\circ}$). Using MRS-N optical spectra, we measure four emission lines (H$\alpha$, [NII]$\lambda$6584, [SII]$\lambda\lambda$6717,6731) and use line-ratios to spectroscopically confirm 255 HII regions, including 90 previously "Known" HII regions and 165 newly classified ones. We measure their $T_{\rm e}$, $n_{\rm e}$ and oxygen abundance, and determine distances via associated OB
stars and the kinematic method. The sample spans $R_{\rm gal}$ from 8.16 to 15.36 kpc, enabling investigation of radial gradients in physical properties. We find [NII]/H$\alpha$ and [SII]/H$\alpha$ decrease with increasing $R_{\rm gal}$, while [SII]/[NII] remains nearly flat; these trends are quite different from diffuse ionized gas (DIG). We derive the $T_{\rm e}$ gradient of 344.530 $\pm$ 78.083 K kpc$^{-1}$, and the $\log n_{\rm e}$ gradient of -0.143 $\pm$ 0.041 cm$^{-3}$ kpc$^{-1}$. Oxygen abundance shows a steep slope of -0.044 $\pm$ 0.010 dex kpc$^{-1}$ in the inner disk and a shallow slope of -0.016 $\pm$ 0.005 dex kpc$^{-1}$ in the outer disk, with a global slope of -0.014 $\pm$ 0.005 dex kpc$^{-1}$. We also examine the two-dimensional distributions of $T_{\rm e}$, $n_{\rm e}$, and oxygen abundance, and find the gradients vary with azimuth. There is no obvious difference between spiral arm and interarm regions, and no trend appears along individual arms. From [NII]/H$\alpha$-[SII]$\lambda$6717/H$\alpha$ diagram, HII regions have a S$^+$/S ratio (0.32), lower than DIG (0.43); however, heavy overlap prevents clear separation from this diagram alone.
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All authors Yunning Zhao, Wei Zhang, Lin Ma, Shiming Wen, Tao Jing, Cheng Li, Zheng Zheng, Aiyuan Yang, Shichao Han, Juanjuan Ren, Jianjun Chen, Hong Wu, Yongheng Zhao
High Energy Astrophysical Phenomena
On the Blueprint of Active Galaxies Producing Neutrinos
Chen Li and Francis Halzen
Based on the observation of the active
galaxies NGC 1068 and TXS 0506+056, and on additional evidence for the sources NGC 4151, CGCG 420-015, NGC 7469, and the Circinus
Galaxy emerging from IceCube data, we make the case for the production of high-energy
neutrinos within a few gravitational radii of supermassive black holes surrounded by a dense
plasma radiating X-rays. X-rays represents the target for the production of
neutrinos by
protons accelerated near the black hole; they also absorb the gamma rays from the decay of neutral pions produced in the same interactions.
Neutrinos with energies of tens of TeV and above originate in photoproduction interactions with X-rays of $0.1 \sim 1$\,keV energy on the $\Delta$ resonance, $p + \gamma \rightarrow \Delta \rightarrow n + \pi^+$. Our analysis of the multimessenger data points to gamma-ray-obscured sources with a characteristic
neutrino flux linearly proportional to the X-ray flux originating within $\sim 10$ gravitational radii of the black holes, with lower values preferred. We speculate on such sources producing the diffuse flux of
neutrinos and
cosmic rays of extragalactic origin.
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High Energy Physics (Phenomenology)
Magnetic dipole moments as probes of doubly-bottom molecular pentaquarks
Ulaş Özdem
We investigate the
magnetic dipole moments of doubly-bottom pentaquark states with
spin-parities $J^P=\tfrac{1}{2}^-$ and $\tfrac{3}{2}^-$, interpreted as hadronic molecules in the $B\Sigma_b$, $B\Sigma_b^{*}$, and $B^{*}\Sigma_b$ configurations. The analysis is performed within the framework of QCD light-cone sum rules employing
photon distribution amplitudes. Our results demonstrate a strong sensitivity of the
magnetic dipole moments to the internal
spin structure and
quark composition of the states. In particular, the light-
quark sector provides the dominant contribution in the $B\Sigma_b$ configuration, while the
magnetic moment of $B\Sigma_b^{*}$ is largely governed by the heavy bottom
quark. For the $B^{*}\Sigma_b$ molecular state, both light and heavy sectors contribute constructively, leading to a significantly enhanced
magnetic dipole moment. These findings indicate that
magnetic dipole moments constitute a sensitive probe of the internal structure of molecular-type doubly-bottom pentaquarks and provide testable predictions for future experimental studies.
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High Energy Astrophysical Phenomena
An extra hard spectral component peaking at sub-GeV in the prompt emission of GRB 260226A
Yi-Yun Huang, Hai-Ming Zhang, Ruo-Yu Liu et al. (+1 more)
The
prompt emission spectra of gamma-ray bursts (GRBs) have long been empirically described by the Band function over the keV–MeV range, whereas several
Fermi/LAT-detected GRBs show evidence for an extra hard component at higher energies. Here we present a joint GBM–LAT study of GRB~260226A, a rare LAT seeded onboard trigger GRB, and find that an extra sub-GeV component is present. In the time-resolved analysis, we find that a cutoff power-law model fits the spectral data of the extra component better than other models at earlier times, while at later times, the broken power-law model is preferred (or at least equally good). Interpreting the early cutoff as the $\gamma\gamma$ absorption implies that the Lorentz factor at early time is lower and increases with time. The low ratio between the peak energy of the extra component and that of the Band component is difficult to explain with a one-zone synchrotron self-Compton (SSC) scenario. Two-zone emission models, such as external inverse Compton scattering of the photosphere emission by relativistic electrons accelerated in internal shocks, could provide a possible explanation.
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All authors Yi-Yun Huang, Hai-Ming Zhang, Ruo-Yu Liu, Xiang-Yu Wang
Quantum Physics
Quantum LDPC codes with design rate 1/5 and good performance below 1000 physical qubits
Yifan Hong
Constant-rate
quantum low-density parity-check (LDPC) codes promise fault-tolerant
quantum computation with constant spatial overhead in the asymptotic limit. Nonetheless, discovering finite-length code instances with good practical performance remains challenging. We introduce a new family of
quantum LDPC codes with design rate $1/5$ and check weight $9$ that approaches the teraquop
memory regime per
qubit-round with several hundred physical
qubits, under idling-free
circuit-level noise of strength $0.1\%$ and GPU-accelerated Relay-belief-propagation (Relay-BP) decoding with average latencies around 1-2 ms, a regime relevant to trapped-ion and neutral-atom processors. The construction involves the balanced product of classical LDPC codes with design rate $1/2$ that share non-abelian $\mathbb{Z}_\ell \rtimes \mathbb{Z}_m$ group
symmetries, which may be of independent interest for classical error correction. We build syndrome extraction
circuits tailored to reconfigurable atom arrays using a simple greedy scheduler, with single-round rearrangement times around 30-60 ms using present hardware specifications, and substantial room for future improvements. We also construct logical Pauli bases that are equivariant with respect to the group
symmetry, which can significantly compress the design space for code surgery. Together, these results further advance the practicality of constant-rate
quantum LDPC codes for near-term, fault-tolerant
quantum computers.
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Adaptation and Self-Organizing Systems
Effect of biharmonic coupling in frequency-weighted Kuramoto oscillators
R. Senthamizhan, R. Gopal and V. K. Chandrasekar
We investigate the collective dynamics of globally coupled phase oscillators with frequency-weighted biharmonic coupling. Although frequency-weighted and biharmonic extensions of the Kuramoto model have each been studied independently, their combined effect has remained unexplored. By combining numerical branch continuation with analytical stability analysis, we construct the complete phase diagram in the two-parameter coupling plane. The competition between the first- and second-harmonic interactions gives rise to three distinct collective states: the incoherent state (IC), the antipodal multibranch state (APMS), and the
symmetry-broken multibranch state (SBMS). These states are separated by three bistable regions and a narrow tristable region in which all three states coexist as stable attractors. The transitions from the incoherent state to both ordered states are discontinuous and hysteretic, reflecting the explosive synchronization induced by frequency weighting, while the transition between the APMS and SBMS is also abrupt. Analytically, we derive the linear instability thresholds of the incoherent state together with the existence and local stability conditions for the SBMS, and show that the theoretical predictions are in good agreement with extensive numerical simulations.
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Mesoscale and Nanoscale Physics
Third-order nonlinear transport in a percolative two-dimensional superconductor
Wenjun Liu, Chenghe Wang, Xiubin Li et al. (+5 more)
Percolative superconductivity frequently arises in two-dimensional van der Waals materials due to reduced dimensionality, enhanced
quantum fluctuations, and complex electron-
phonon interactions, providing a unique platform where normal electrons coexist with Cooper pairs. We report the observation of substantial third-order nonlinear transport in a trilayer $1T^\prime$-MoTe$_2$
superconductor within its percolative transition regime. The third-harmonic longitudinal voltage ($V_{\|}^{3\omega}$) exhibits a clear cubic dependence on excitation current below a threshold, with both its magnitude and nonlinear coefficient strongly correlated with the superconducting state. This nonlinear response is semiquantitatively captured by the superconducting fluctuation within the time-dependent Ginzburg-Landau theory, where nonlinear transport arises due to fluctuating Cooper pairs. Our results demonstrate that third-order nonlinear transport serves as a sensitive probe of superconducting transitions in percolative systems and establish a foundation for exploring higher-order transport phenomena in strongly correlated systems.
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All authors Wenjun Liu, Chenghe Wang, Xiubin Li, Kenji Watanabe, Takashi Taniguchi, Tao Zhang, Xiao-Xiao Zhang, Jing Li
Instrumentation and Methods for Astrophysics
Design and testing progress towards the first flight of the rocket experiment demonstration of a Soft X-ray Polarimeter (REDSoX)
Sarah N.T. Heine, Herman L. Marshall, Alan Garner et al. (+11 more)
The Rocket Experiment Demonstration of a Soft X-ray Polarimeter (REDSoX) is a NASA-funded, sounding rocket mission. The rocket payload will measure polarization strength and direction as a function of energy in the 0.2-0.4 keV band, providing complementary measurements to those made by IXPE in the 2-8 keV band. The first flight, scheduled for 2028, will provide a technology demonstration of our polarimeter concept, which utilizes an aligned system of a focusing optic, Critical-Angle Transmission (CAT) gratings, Laterally Graded Multilayer (LGML) mirrors, and Charge Coupled Device (CCD) detectors to measure polarization. We will describe the design of the instrument post-critical design review, the status of flight hardware testing, and payload assembly.
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All authors Sarah N.T. Heine, Herman L. Marshall, Alan Garner, F. Elio Angile, C. Marc Baker, Stephen Bongiorno, Leonardo Drake, H. Moritz Gunther, Ralf K. Heilmann, Beverly LaMarr, Sean McNeil, Jill Juneau, Swati Ravi, Eric Gullikson
Materials Science
Physics to Circuit Analysis of GaN RF Integrated Circuits versus GaAs and Silicon
Harkirat Kaur, Palak Kapoor and Rajesh Vedala
The migration of
radio-frequency (RF) integrated-
circuit platforms from silicon to GaAs and now to gallium nitride is derived here from first principles. The hexagonal non-centrosymmetric GaN
lattice admits a macroscopic polarization; elasticity and the piezoelectric tensor fix the bound sheet charge at an AlGaN/GaN interface, and Poisson's equation with triangular-well quantisation yields a degenerate quasi-two-dimensional channel of ~10^13 cm^-2 with no doping. Energy-momentum conservation for pair creation and
phonon-limited energy relaxation set the breakdown field (3.3 MV/cm) and saturation velocity (2.5 x 10^7 cm/s), which combine into geometry-free limits V_brf_T = E_cv_sat/(2pi) and R_on^sp = 4V_br^2/(muepsilonE_c^3). These limits are mapped onto the low-noise amplifier, power amplifier, and switch/phase-shifter functions of a transmit/receive front end and quantified by a MATLAB device-physics model comparing GaN, GaAs, and Si up to 90 GHz. The purpose of this framework and its simulations is to identify which material platform offers the best performance at millimeter-wave frequency signals.
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Physics and Society
Targeted Quarantine Strategies Mitigate SIS-model Cyber Epidemics on Complex Networks
Ho Yuen Wong and Tak Shing Tai
The rapid expansion of highly connected and heterogeneous digital infrastructures has fundamentally altered the dynamics of cyber epidemics, making it increasingly important to understand how malware propagates under realistic structural and policy conditions. In this study, we employ an SIS epidemic model on complex networks to investigate virus spreading under a range of cybersecurity scenarios, including minimally protected environments, anti-virus, vulnerable legacy systems, mixed security systems, rapidly evolving virus, and targeted quarantine of key nodes. Using simulations on scale-free
topologies, we characterize how infection prevalence evolves over time and identify conditions under which outbreaks become explosive versus controlled. Our results show that vulnerable and rapidly evolving virus scenarios lead to fast and almost complete compromise, while antivirus and mixed-security configurations significantly reduce peak infection levels. Most importantly, we demonstrate that targeted quarantine of a small fraction of structurally important nodes can both delay the onset of large scale outbreaks and lower steady state infection, revealing a threshold in the fraction of quarantined nodes which required to alter spreading of computer virus. These findings highlight the critical role of network
topology and selective protection in enhancing the resilience of cyber-physical infrastructures.
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High Energy Astrophysical Phenomena
Depolarization Induced by Rapid Polarization Angle Swings: A Common Feature of Pulsars and Fast Radio Bursts?
Yu-Chen Huang, Jie-Shuang Wang, Song-Bo Zhang et al. (+1 more)
The polarization angle (PA) of
pulsars and fast
radio bursts (FRBs) provides a useful diagnostic of the
magnetic fields in their emission regions and is therefore crucial for understanding their radiation and origins. Within a general
geometric framework for polarized emission from a rotating
neutron star, we suggest a possible anti-correlation between the degree of linear polarization $\Pi_\text{L}$ and $d\text{PA}/dt$, the time derivative of the PA, as a common feature of
pulsars and FRBs. The depolarization arises from the incoherent superposition of radiation with different polarization directions within the observable part of the emission region, and is detectable only when the PA swing is steep enough. We test this
conjecture using a sample of
radio pulsars and find possible evidence for the expected anti-correlation in a subset of
pulsars. Whether this relation holds in FRBs remains uncertain due to limited observational data. Identification of this feature would not only provide insights into the rotating magnetospheric origin of FRBs, but also place constraints on the
spin periods and
geometric parameters of the
neutron stars that power these mysterious bursts.
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All authors Yu-Chen Huang, Jie-Shuang Wang, Song-Bo Zhang, Zi-Gao Dai
Mathematical Physics · Cross-listed from math.PR
Regularized Bulk Universality versus Bounded-Disorder Nonuniversality for Annealed Complexity of Spherical $p$-Spin Landscapes
Taegyun Kim
Fix $p\ge 3$. We establish a separation between regularized bulk universality and unrestricted annealed complexity for the pure spherical $p$-
spin Hamiltonian with independent non-Gaussian tensor coordinates. There is a symmetric, compactly supported disorder law with a smooth density, matching the first $2p$ Gaussian moments, for which the expectation of a positive, frame-averaged regularization of the one-point Kac-Rice functional is asymptotic to its Gaussian counterpart, while the unrestricted critical-point count in a compact energy window has a lower exponential rate strictly above the Gaussian limit. The obstruction is a coherent block involving on the order of $N^{1/p}$ coordinates, so neither finite moment matching nor a uniform entry bound restores unregularized annealed universality. For uniformly subexponential disorder matching the first $m$ Gaussian moments, the regularized functional on incoherent frames satisfies $\left|\log\left(\mathbb{E}\mathcal{Z}_{N,L}^J/\mathbb{E}\mathcal{Z}_{N,L}^G\right)\right|\le C N q_N^{m-1}$, where $q_N=L^{p-1}N^{-(p-2)/2}(\log N)^{(p-1)/2}$. Thus mean and variance matching imply regularized pressure universality for every $p\ge 3$, and the expectation ratio tends to one when $(m-1)(p-2)>2$. We identify the Gaussian variational limit and prove the Gaussian quadratic energy-excursion upper bound uniformly over profiles asymptotically supported on $o(N)$ coordinates under a Gaussian-rate profile-tail condition. Finally, we give a conditional reduction to exact universality: once two one-sided de-regularization defects vanish, an exact max formula makes control of the localized complement necessary and sufficient. The defects vanish in the Gaussian model.
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Materials Science
Anisotropic Tensile Strength and Fracture Mechanism of $\theta$-TaN: A Machine-Learning Potential Molecular Dynamics Study
Chenyang Cao, Hongfei Li and Shuo Cao
theta-phase tantalum nitride (theta-TaN) combines metallic conductivity with exceptionally high thermal conductivity, making it a potential material for device thermal management and interconnect applications. However, its tensile strength and fracture behavior remain unclear. Here, we investigate the anisotropic tensile response and fracture mechanism of theta-TaN using neuroevolution-potential molecular dynamics simulations. Size-convergence tests show that a 20 nm long model is sufficient for reliable prediction, and the mechanical parameters vary by less than 3.5% over the strain-rate range of 10^7 to 10^9 s^-1. The results reveal strong tensile anisotropy. The c-axis direction ([0001]) shows a higher strength of 80.10 GPa and modulus of 748.63 GPa, but a lower fracture strain of 15.02%. In contrast, the a-axis direction ([2-1-10]) shows a lower strength of 56.87 GPa and modulus of 570.74 GPa, but a higher fracture strain of 17.71%. From 300 to 900 K, the mechanical properties decrease nearly linearly, while more than 73% of the 300 K strength is retained at 900 K. Fracture occurs without observable dislocation activity and is governed by cleavage-plane selection: {10-10} prismatic planes under a-axis tension and the (0001) basal plane under c-axis tension. Atomic displacement analysis shows that local separation and microvoid formation precede macroscopic crack growth, indicating a brittle fracture process driven by local bond-network instability. These results provide atomic-scale mechanical data for assessing the reliability of theta-TaN in thermal management applications.
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Superconductivity
Single-crystal structural phase diagram of stoichiometric bilayer nickelate La3Ni2O7 under hydrostatic pressure
Misaki Sasaki, Zhehong Liu, Takeshi Hara et al. (+12 more)
The
bilayer nickelate La3Ni2O7 has attracted intense interest following the discovery of high-temperature superconductivity under pressure, representing the first nickelate
superconductor realized in bulk form. However, the
crystal structure of the superconducting phase remains under active discussion, complicating efforts to establish its microscopic origin. Here we resolve these structural controversies by establishing a definitive pressure-temperature phase diagram, including the superconducting region of stoichiometric La3Ni2O7 single
crystals under hydrostatic conditions using helium as the pressure-transmitting medium. At ambient pressure, La3Ni2O7 adopts a polar orthorhombic Am2m structure characterized by charge order between inequivalent Ni sites and NiO6 octahedral tilting. Upon compression, the system undergoes a direct transition from the charge-ordered Am2m phase to the tetragonal I4/mmm phase near 10 GPa, coinciding with the onset of bulk superconductivity. These results establish the intrinsic structural
evolution of La3Ni2O7 and provide a structural framework for microscopic theories of nickelate superconductivity.
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All authors Misaki Sasaki, Zhehong Liu, Takeshi Hara, Shunsuke Kitou, Markus Kriener, Haruto Yoshimochi, Shion Yamada, Chieko Terakura, Naohisa Hirao, Hirokazu Kadobayashi, Yusuke Wakabayashi, Yoshinori Tokura, Yasujiro Taguchi, Taka-hisa Arima, Yukako Fujishiro
High Energy Physics (Phenomenology)
Unbiased Data-Driven Determination of the Nuclear Dipole Amplitude in the Color Glass Condensate
Si-Wei Dai, Haowu Duan, Long-Gang Pang et al. (+4 more)
Gluon saturation limits the growth of parton densities at small Bjorken-$x$ and is expected to be most pronounced in heavy
nuclei. Yet quantitative extractions of the
nuclear gluon dipole amplitude have long relied on parametrized initial conditions, introducing uncontrolled model dependence that obscures genuine
nuclear effects. We introduce a physics-informed neural-network framework that embeds the collinearly improved Balitsky-Kovchegov
evolution equation directly into the training objective, allowing the impact-parameter-averaged dipole amplitude to be determined from data without assuming a functional form for its initial condition. Applying this framework to forward-
hadron nuclear-modification-factor and coherent $J/\psi$ photoproduction data, we extract the $^{208}$Pb dipole amplitude at $x_0=0.01$ with QCD
evolution and momentum-space positivity enforced throughout training. The evolved amplitude reproduces the measured cross sections across the available kinematic range and yields a saturation-scale ratio $Q_{s0,\mathrm{Pb}}^2/Q_{s0,p}^2 = 3.17^{+0.17}_{-0.10}$, consistent with simple
geometric scaling. The extracted Pb initial condition is well described by a McLerran-Venugopalan-type form, in contrast to the
proton, reflecting the higher color-charge density of a large
nucleus. Using the same amplitude, we predict the rapidity dependence of the transverse-momentum ratio in $pp$, $p$Pb, and Pb$p$ collisions, finding agreement with recent LHCb measurements at low multiplicity without any system-dependent parameters. This work provides the first unbiased, data-driven determination of
nuclear structure in the saturation regime and establishes a general strategy for
embedding nonlinear
evolution equations into machine-learning extractions of dynamically constrained observables.
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All authors Si-Wei Dai, Haowu Duan, Long-Gang Pang, Guang-You Qin, Shu-Yi Wei, Han-Zhong Zhang, Wenbin Zhao