Materials Science
d-band filling dictates magnetic stability in Mn- and Co-substituted FeRh alloys
Greeshma R and Rudra Banerjee
The composition-dependent
magnetic properties of B2-ordered \zfr~
alloys with substitutional disorder on the Fe sublattice are investigated using first-principles calculations within the coherent potential approximation. By systematically substituting Mn and Co on the Fe sublattice, we establish $d$-band filling as the primary control parameter governing
magnetic stability in this itinerant system. Mn substitution (hole doping) shifts the
Fermi level into the minority-
spin bonding states, driving a collapse of
spin polarization (crossing zero at $x \approx 0.5$) and the emergence of competing
antiferromagnetic interactions ($\eta_\mathrm{Mn} < 0$). Even though the
ferromagnetic configuration remains energetically well separated from the G-type AFM-II configuration across the studied range ($\Delta E$ up to $\sim$0.35~eV/atom), this exchange competition drives an “itinerant
magnetic softness” that suppresses the Curie temperature by $\sim$450~K – a finite-temperature instability set by the near-cancellation of competing exchange interactions rather than by AFM–FM energy proximity. In contrast, Co substitution (electron doping) acts as a “
magnetic hardener” by pinning the
Fermi level within the majority-
spin pseudogap, preserving high
spin polarization ($|P| \approx 0.75$) and stabilizing
ferromagnetic exchange across the full composition range. These results show that tuning the
Fermi level relative to the pseudogap provides a systematic, microscopic framework for controlling
magnetic stability in B2-ordered itinerant magnets, distinct from simple magneto-volume models.
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Biological Physics · Cross-listed from q-bio.PE
How genome redundancy can promote evolutionary innovation
Domenico Caudo, Mattia Miotto, Giancarlo Ruocco et al. (+1 more)
Polyploidy is defined as the existence of more than two complete sets of homologous chromosomes. Despite it being a widespread phenomenon across the tree of life, its role as either an evolutionary innovation or a dead end is still debated. Here, we investigate how under varying selective pressures the degree of ploidy interacts with two key biological factors: the mode of inheritance and the genotype-phenotype mapping. Through a minimal evolutionary model we find that polyploidy is especially advantageous during abrupt environmental changes, confirming that polyploidization is often associated with ecological upheavals. We observe that
stochastic inheritance combined with a nonlinear (maximum-based) genotype-phenotype mapping maximizes both phenotypic exploitation and landscape exploration across all environments. By contrast, structured inheritance with an additive phenotype mapping systematically underperforms, yet displays a pronounced optimum at low-to-intermediate ploidy level that mirrors the distribution observed in natural plant and bacterial populations. When individuals are free to carry different chromosome numbers, selection drives the population toward values that reflect an interplay between exploitation, exploration, and convergence speed rather than any single evolutionary objective. The relative weight of these three factors depends on the fitness landscape, providing a unifying framework for understanding when and why polyploidy is favored by natural selection.
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All authors Domenico Caudo, Mattia Miotto, Giancarlo Ruocco, Greta Grassmann
Solar and Stellar Astrophysics
Sloshing Oscillations in coronal loops excited by successive M- and C-Class flares
Hitesh Paliwal, S. Krishna Prasad and M. V. Sunil Krishna
Slow magnetoacoustic waves in hot coronal loops have remained a topic of considerable interest and debate over the past two decades. The periodic back-and-forth motion of
plasma within a coronal loop, often initiated by a
flare, is commonly referred to as sloshing oscillation. In the present study, we report unprecedented observations of sloshing oscillations in coronal loops excited by successive M- and C-class
flares, using data from the Atmospheric Imaging Assembly (AIA) onboard the
Solar Dynamics Observatory (SDO). A total of fifteen oscillation events were identified within seven distinct coronal loops, providing the rare opportunity to evaluate the influence of
flare strength on the characteristics of the oscillations. Based on the appearance of the oscillations, their properties were extracted mainly from the AIA 131 and 94 Å channels. Additionally, we estimate the deprojected length of each loop by assuming a semi-circular geometry. Our results indicate considerable changes in the properties of oscillations from one
flare to another, suggesting the role of individual
flares in shaping the local physical conditions. The
plasma temperature estimated from the loop length and oscillation period ranges from 9 to 31 MK. Additionally, we find that the damping times are not always longer in the colder 94 Å channel as previously observed. By combining the results obtained from all events, we study the inter-dependences between various parameters, including oscillation period, damping time, loop length, and
plasma temperature, and discuss these results in the context of the theory of slow waves.
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Soft Condensed Matter
History-dependent discharge of compressed particle rafts
Mario Nabernik, Gregor Plohl, Kathrin Schulte et al. (+1 more)
While particle-laden interfaces play a central role in many natural and industrial processes, predicting their mechanical properties remains a major challenge. These systems combine granular characteristics conferred by particle-particle contacts with elastic behavior originating from capillary interactions, making them very sensitive to their history. Using the relaxation of uniaxially compressed particle rafts through a local constriction as a model experiment, we demonstrate the existence of a reproducible and continuous aging process. Aging is observed for both front- and back-compressed rafts and is characterized by a progressive increase in particle mobility and raft deformability. Macroscopic changes are seen, for example, in the extent of relaxation and are correlated with flow modifications observed at the mesoscopic level among which are increased particle fluxes, broader shear zones and enhanced particle rearrangements. While aging can be attributed unambiguously to the constrained passage of the particles through a constriction, its microscopic origin remains hypothetical, the results suggesting that contact lines around the particles may evolve. Beyond providing new insight into the effects of raft history, the proposed constriction flow experiment offers a simple method to control and compare aging in different particulate assemblies.
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All authors Mario Nabernik, Gregor Plohl, Kathrin Schulte, Carole Planchette
Solar and Stellar Astrophysics
Dual-Perspective Microwave and Hard X-ray Constraints of Asymmetric Nonthermal Loops in an X-class Flare
Ruifei Huang, Yao Chen, Victor Melnikov et al. (+9 more)
We report dual-perspective microwave and HXR observations of an X-class
flare on 2024 May 15, taking advantage of the unique geometry of a front-side view from the Earth and a back-side perspective from the
Solar Orbiter (SolO). Using spatially resolved imaging spectroscopy from Siberian Radioheliograph (SRH) together with Chashan Broadband
Solar millimeter spectrometer (CBSmm) and STIX data, we identify a set of nonthermal flaring loops in an asymmetric
magnetic field, with microwave sources located near the loop top and HXR sources associated with the southern footpoint. Compared with HXR, the microwave emission shows an opposite ascending trend, an increasing time lag in time profile, and a distinctive “SHH” spectral pattern, which we attribute to energy-dependent trapping and precipitation of energetic electrons in an asymmetric
magnetic configuration. Flux pulsations and their spectral and polarization signatures are consistent with intermittent particle acceleration rather than MHD wave modulation. Microwave
magnetic diagnostics, corroborated by non-linear force free field (NLFFF) extrapolation, provide key constraints on the three-dimensional
magnetic configuration. The dual-perspective flux profile comparison and consistent QPP signatures across wavelengths together support a self-consistent picture of energy-dependent electron trapping, precipitation, and transport in these asymmetric loops.
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All authors Ruifei Huang, Yao Chen, Victor Melnikov, Alexey Kuznetsov, Zhao Wu, Dmitriy Smirnov, Sergey Anfinogentov, Feiyu Yu, Xiangliang Kong, Ze Zhong, Mingzhe Guo, Hao Ning
Instrumentation and Methods for Astrophysics
The IRT Telescope on board the THESEUS mission
Diego Gotz, Aline Meuris, Eric Doumayrou et al. (+28 more)
We present the Infra-Red
Telescope (IRT), which is part of the payload of the THESEUS mission, one on the three phase A candidate missions for the M7 slot of ESA (launch date 2037). The IRT is a 0.7 m class
telescope with an off-axis Korsch optical design, with imaging capabilities in the 0.7-1.8 microns range over a 15 x 15 arc min field of view. The IRT also provides slit-less low resolution spectroscopy (R~400) over a limited field of view of 2 x 2 arc min, in the 0.8-1.6 microns range. The goal of the IRT is to identify the near infrared counterparts to the Gamma-Ray Bursts (GRBs) detected by the two other
telescopes on board THESEUS (the XGIS and the SXI), and to measure on board its photometric
redshift in near real-time. The position and the
redshift will be transmitted immediately to ground to allow for deeper follow-up by the large
telescopes (ELT, VLT, ...). If the source is bright enough, spectroscopy will be performed to characterize the GRB environment.
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All authors Diego Gotz, Aline Meuris, Eric Doumayrou, Dehbia Lattab, Frederic Pinsard, Samuel Ronayette, Thierry Tourrette, Herni Triou, Bortolino Saggin, Marco Giovanni Corti, Stefano Covino, Fabrizio Fornasiero, Luca Oggioni, Luca Terenzi, Stephane Basa, Enrico Bozzo, Ludovic Genolet, Lauro Conti, Mariachiara Celato, Paul Hedderman, Shaymaa Hussein, Christoph Tenzer, Karine Mercier, Lander Ruiz de Ocenda, Jean-Michel Le Duigou, Adrien Fort, Florent Robinet, Andras Peter Joo, Rebeka Kiss, Bendeguz Koncz, L. Viktor Toth
Materials Science · Cross-listed from stat.ME
Fitting the topology of synthetic particle systems with a novel graph representation
Martin Alexander Memmesheimer and Claudia Redenbach
The shape and arrangement of particles in a material determine its macroscopic properties. The generation of synthetic data with varying particle structure, often represented as 3D voxel images, combined with simulation of macroscopic properties reveals structure-property relations. Most particle generation models focus on single-particle characteristics like shape and size. We aim at fitting the
topology of the particle system using tools from persistent homology. However, the large size of the required 3D image data makes existing methods computationally infeasible. We bridge this gap by introducing a novel graph representation of particle systems and transferring the computation of persistent homology from the image domain to the graph domain. This yields a postprocessing method for synthetic images of particle systems, that is independent of the underlying generation method and improves topological and geometrical agreement with real particle systems while preserving morphological characteristics such as the particle size distribution.
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Quantum Physics
Variance-Reduced Trajectory Unravelings for GPU Noisy Quantum-Circuit Simulation: Characterization and a Qiskit-Aer Integration Gap
Chun-Yeol You
Monte-Carlo trajectory (
quantum-jump) methods are the practical route to simulating noisy
quantum circuits once the exact density-
matrix method is precluded by its $4^n$
memory cost. Their bottleneck is
estimator variance: resolving one expectation value can demand thousands of trajectories. Recent tensor-network work shows that variance-reduced unravelings – projector and analog sampling – sharply cut this variance, but only on CPU
matrix-product-state backends, with no path into production tooling. We implement both unravelings on a GPU dense-statevector trajectory engine and validate them against the exact density
matrix (ideal-
circuit fidelity $1-2.2\times10^{-16}$; $1/\sqrt{N}$ convergence; all unravelings unbiased to trace distance $<0.01$). On a single consumer GPU, projector unraveling reaches a target standard error with $20.8\times$ fewer trajectories than Qiskit-Aer's batched\_shots\_gpu at $n=10$, a factor that holds at $19$–$26\times$ across $n=8$–$20$. A regime map places analog sampling optimal at weak noise and projector at strong noise, crossing near $\gamma t\approx0.35$. We further report a systems finding: Qiskit-Aer applies noise at the channel level and reconstructs a canonical Kraus decomposition at apply time, discarding any user-supplied unraveling, so variance-reduced unravelings cannot be delivered through its public API. Because Aer's Born-rule collapse machinery already exists, we specify a minimal change that would unlock the technique in production.
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Mesoscale and Nanoscale Physics
Lorentz-Covariant Landau Levels of Tilted Dirac Fermions in Nonuniform Fields
Sushmita Saha and Alestin Mawrie
We develop an analytical theory of Landau quantization for tilted anisotropic Dirac
fermions in an exponentially decaying
magnetic field. Using anisotropy scaling and a Lorentz transformation, we recast the laboratory-frame problem into the isotropic Dirac equation in the boosted frame, where the exponentially decaying
magnetic-field problem admits an exact solution. Transforming the boosted-frame spectrum back to the laboratory frame yields an implicit quantization condition with an intrinsically energy-dependent guiding-center parameter. We identify the conditions for physically admissible states. We further show that the formalism recovers the known uniform-field spectrum of tilted anisotropic Dirac
fermions in the appropriate limit. Our results extend the Lorentz-covariant treatment of tilted anisotropic Dirac
fermions to an exponentially decaying
magnetic field and reveal the energy-dependent guiding-center structure generated by the inverse transformation to the laboratory frame.
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Chemical Physics
Vibrational Circular Dichroism enhancement in conformationally flexible transition metal complexes
Mariia Sapova, Menno de Boer, Wybren Jan Buma et al. (+1 more)
We extend our previously developed approach for calculating enhanced vibrational circular dichroism (VCD) spectra of transition-metal complexes to systems for which conformational flexibility is key to reproduce and elucidate experimental spectra. Treating both the Gibbs free energies and electronic excitation energies as fitting parameters, we show for Co(II)bis[N-(1-arylethyl)- salicylaldiminato] Schiff base complexes that these calculations can excellently reproduce the experiment. An important conclusion is that the DFT-optimized conformer set is spectrally redundant and that the model can be reduced from 18 conformers to only two conformers with opposite chirality at the metal center ($\Lambda$/$\Delta$) without affecting the agreement between theory and experiment, both with respect to the VCD spectrum as well population distribution over the $\Lambda$ and $\Delta$ conformers. Finally, we numerically confirm the
symmetry-selective nature of the enhancement and formulate the corresponding selection rules within the framework of the pertaining Sum-Over-States expressions.
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All authors Mariia Sapova, Menno de Boer, Wybren Jan Buma, Lucas Visscher
High Energy Astrophysical Phenomena
Time-dependent Accretion Disks in Tidal Disruption Events: Long-term Light Curves
Chenlei Guo and Erlin Qiao
The time-dependent
accretion disk has been applied to explain the light curves observed in
tidal disruption events (TDEs). Radiation pressure instability is expected to be an important factor that can shape the
evolution of the
accretion disk. In this paper, we upgrade the time-dependent disk model in Guo $\&$ Qiao by incorporating an index $\mu$ (with the stress tensor $\propto p^{\mu}p^{1-\mu}_{\rm{gas}}$, where $p=p_{\rm{gas}} + p_{\rm{rad}}$) for the modified viscosity, and a parameter $f_{\rm{w}}$ for the strength of the wind. Meanwhile, we adopt a more realistic fallback rate to inject into the disk. After systematically testing the effects of the newly incorporated parameters, we find that $f_{\rm{w}}$ can affect the time when the instability occurs, while $\mu$ can influence the occurrence and variation magnitude of the radiation pressure instability. When $\mu<0.4$, the radiation pressure instability is completely removed from the disk, and the light curves evolve stably without large-scale magnitude variation. When $\mu>0.4$, the light curves can show oscillations caused by the instability, or drop steeply when the instability occurs and become flat in the late-time
evolution, which mainly occurs when the viscous viscosity parameter $\alpha$ is small or the impact parameter $\beta$ is small. Since the drop magnitude can be modulated by $\mu$, we apply these `decay-to-flatten' light curves to some optical/UV observations in TDEs with different magnitudes of decline. Finally, we discuss the potential application of our model to some special TDEs that show oscillations in the light curves.
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General Relativity and Quantum Cosmology
Harmonic oscillation and orbital morphology for spinning charged quantum corrected black hole
Rameez Khalid, Muhammad Yasir, Shahid Qaisar et al. (+1 more)
This study investigates the dynamical behavior of particle's test around a spinning charged Einstein-Maxwell-dilaton (EMd)
quantum corrected black hole (QCBH) by examining the effects of spinning parameter $a$,
quantum correction parameter $b$, and charge parameter $Q$. Using EMd spacetime geometry, we analyze the effective potential and effective force to determine the stability and structure of the circular orbits in a strong gravitational field. Furthermore, we calculate the oscillation frequencies radial $(\Omega_r)$, vertical $(\Omega_\theta)$, and angular $(\Omega_\phi)$, as well as the corresponding Periapsis and Lense-Thirring precession frequencies. The
spin parameter primarily determines the spinning properties of spacetime, while the
quantum correction and charge particle introduce additional biases to Kerr-Newman geometry, particularly near the event horizon. These corrections alter the position and stability of the circular orbits, and the spectrum effectively associates with particle's motion. The results provide a comprehensive description of the orbital dynamics of spinning EMd QCBH through future high-precision astrophysical observations.
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All authors Rameez Khalid, Muhammad Yasir, Shahid Qaisar, Faisal Javed
Solar and Stellar Astrophysics
CW Cas: A solar-type contact binary system with an unseen third companion in a hierarchical quadruple system
Azizbek Matekov, Liying Zhu, Linjia Li et al. (+11 more)
We present a comprehensive multiband photometric and spectroscopic study of the G-type binary CW Cas whose parameters have not been well determined. Our double-lined spectroscopic radial velocity curve of this system yields a reliable mass ratio of $q = 1.88(9)$. By combining $BVR_{c}I_{c}$ bands, TESS light curves and radial velocity curves, we found that CW Cas is a W-subtype shallow contact binary with a fill-out factor of 15%. The components have masses of $0.98(6)M_{\odot}$ and $0.52(4)M_{\odot}$, separated by $2.25(5)R_{\odot}$. A notable asymmetry in the maxima of the light curves was detected and explained by a dark spot located on the surface of at least one component. Comparison of light curves from different years revealed that these dark spot activities exhibit cyclic variations with an approximate period of 1250 days. Orbital period analysis via O-C diagram spanning 125 years shows a long-term decrease superimposed with periodic oscillation caused by the light-travel-time effect (LTTE) due to a third body. This tertiary component has an orbital period of $P_{3} = 99.4(6)$ years and a minimal mass of $M_{3}=0.91(1)M_{\odot}$. The absence of detectable signatures for this massive object in either spectroscopic or photometric
datasets implies it must be a compact object such as a white
dwarf or
neutron star. Furthermore, a visual companion was identified based on
Gaia DR3 astrometric data, suggesting that CW Cas is part of a hierarchical quadruple system. As such, CW Cas represents a valuable laboratory for probing 2+1+1 hierarchical multiple system hosting compact object.
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All authors Azizbek Matekov, Liying Zhu, Linjia Li, Fangbin Meng, Nianping Liu, ShengBang Qian, Ergang Zhao, Mikhail Kovalev, Jiangjiao Wang, Yufei Chen, Aktam Hafizov, Soonthornthum Boonrucksar, Somsawat Rattanasoon, Shuhrat Ehgamberdiev
Earth and Planetary Astrophysics
Probing disk dynamics and dust evolution through shadows in protoplanetary disks: A case study of the HD 142527 disk
Yuya Fukuhara, Ryuta Orihara, Satoshi Okuzumi et al. (+1 more)
Planet formation begins with
dust growth and planetesimal formation within protoplanetary disks surrounding young
stars. To understand these processes, it is essential to estimate
dust grain sizes from disk observations. In this study, we develop a new method to constrain grain size based on the estimation of cooling timescales. Our approach applies to transitional disks that possess an inclined inner disk casting shadows on the outer disk, whose temperature variations serve as a tracer of
dust properties. By constructing a three-dimensional model of the disk surface using near-infrared scattering light images and comparing it with submillimeter
dust continuum maps, we estimate the spatial offset between the irradiated and shadowed regions to derive the cooling timescale. We then build an analytic model that calculates the cooling timescale at the
dust thermal emission height with an assumed turbulent
diffusion intensity to infer the
dust surface density and
dust grain size. Applying this method to the protoplanetary disk around HD~142527, we find that the disk's northern shadowed region cools on a timescale of a few percent of the orbital period and that the maximum grain size consistent with the observations is approximately 0.1-1 mm. We also find that the conditions required for the vertical shear instability, which needs a short cooling timescale, are satisfied, allowing
turbulence with an intensity consistent with near-infrared observations. This study demonstrates that estimating cooling timescales is an effective tool for constraining
dust grain size. Our approach can be generally applied to other transition disks with inner-disk-induced shadows.
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All authors Yuya Fukuhara, Ryuta Orihara, Satoshi Okuzumi, Takayuki Muto
Quantum Physics
Active Optical Frequency Measurements with Superradiance Prolonged by a Modulated Magnetic Field
Huihui Yu, Shi-Lei Su, Chongxin Shan et al. (+2 more)
Superradiant emission from long-lived excited states of an atomic ensemble confined in an optical cavity constitutes a practical source of light with narrow linewidth. In the pulsed regime, however, superradiance implies rapid emission and a broadening of the spectrum. Recent experiments have demonstrated constructive and destructive interference of superradiant emission by different strontium atomic transitions. In this article, we show that by modulating the atomic transition frequencies with a
magnetic field, it is possible to control the release of the atomic excitation energy as a prolonged pulse or a train of superradiant pulses. By simulations, we show that heterodyne detection of the prolonged superradiance shows extremely sharp spectral features, which leads to significantly reduced frequency uncertainty and fluctuation.
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All authors Huihui Yu, Shi-Lei Su, Chongxin Shan, Klaus Mølmer, Yuan Zhang
Mathematical Physics
Baxter Q-operators from a Schwinger-Boson construction of the master T-operator and the mKP hierarchy
Zengo Tsuboi
The master T-operator is a generating function for transfer
matrices and a tau-function of the modified KP (mKP) hierarchy. It is conventionally introduced through a Schur-function expansion whose coefficients are fused transfer
matrices satisfying the Cherednik–Bazhanov–Reshetikhin determinant formula. For rational inhomogeneous gl(M)
spin chains, we give an alternative definition: we realize gl(M) on an auxiliary Fock space generated by finitely many families of Schwinger
bosons, form a monodromy
matrix from the resulting L-operator, and define the master T-operator as its trace over the Fock space. Howe duality then reproduces the Schur-function expansion. This realization relates two constructions of Baxter Q-operators. In the construction of [arXiv:1112.3310] (see also [arXiv:1010.4022]), the Q-operators are obtained from residues of the master T-operator with respect to selected Miwa variables. In the construction of [arXiv:1010.3699], they are defined using degenerate Yangian L-operators in oscillator form. When selected Miwa variables approach the inverses of boundary-twist
eigenvalues, the defining trace develops poles. After a suitable rescaling of this L-operator, only the terms contributing to the highest-order pole survive in the normalized limit; before the trace is taken, they form the degenerate Yangian L-operator of the second construction. The trace then gives an explicit residue formula for the corresponding Q-operator. Independently, a Holstein–Primakoff-type large-occupation-number contraction of this L-operator on subspaces with fixed total occupation numbers yields the same degenerate Yangian L-operator.
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Instrumentation and Methods for Astrophysics
Optimal mode-sorting coronagraphy: limits of single-moded measurements for the Habitable Worlds Observatory
Yinzi Xin, Sebastiaan Haffert and Rico Landman
Conventional coronagraph architectures struggle to reach the theoretical limit of
exoplanet detection at close working angles. Spatial mode-sorting is capable of reaching the theoretical limit, which previous work has calculated for a completely unresolved
star whose signal lies entirely in the fundamental piston mode of the
telescope. More recently, we have calculated optimized nulling modes as a function of the size of the
star and
planet parameters, with the goal of improving coronagraphic performance at ~l/D working angles given partially resolved
stars and complex
telescope apertures. In this work, we further explore the limits of a coronagraph involving the measurement of a single spatial mode, with potential applications for the infrared arm of the Habitable Worlds Observatory. We present the achievable single-channel 1 l/D
planet throughput as a function of the single-channel
stellar suppression (for a 0.03 l/D diameter
star), and show that the ability to measure a single optimized spatial mode can allow us to reach at least ~80% of the theoretical information limit.
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Optics
Ghost-wave momentum bandgaps in anisotropic Floquet lattices
Junhua Dong, Huan He and Huanan Li
Momentum bandgaps, characterized by complex frequencies and non-resonant amplification effects, provide a powerful route for wave manipulation beyond conventional band theory. Here, we introduce a distinct mechanism for momentum-gap engineering in higher-dimensional Schrödinger-type Floquet
lattices by exploiting the intrinsically complex wave vectors of ghost waves, with complex-frequency excitation providing an additional degree of freedom for continuously tailoring the ghost-wave branch and the associated Floquet spectrum. Furthermore, we show that the higher-dimensional Floquet band structure supports momentum bandgaps extending across the entire Brillouin zone along the propagation direction and enables amplification over a broad frequency range under arbitrarily weak modulation. When the
lattice is truncated along the ghost-wave decay direction, the resulting Floquet waveguide exhibits broadband reflectionless pulse amplification. Our results establish a higher-dimensional framework for ghost-wave momentum-gap physics and reveal new opportunities for non-Bloch wave engineering in time-varying photonic systems.
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Quantum Physics
Fully-connected three-mode squeezed vacuum: Gaussian entanglement, steering, and collective photon subtraction
Manjia Mai, Jifeng Sun, Teng Zhao et al. (+2 more)
We investigate a fully-connected three-mode squeezed
vacuum (FC-C3MSV) state, where all three modes are pairwise coupled through nonlinear interactions in a triangle ($K_3$)
topology. Using the integration-within-ordered-product technique, we derive the normal product form of the squeezing operator and obtain the covariance
matrix directly from the Bogoliubov transformation. Under symmetric coupling, the physical state is genuinely tripartite entangled for any nonzero squeezing, while the three Armstrong-type witnesses provide a finite-window sufficient experimental test; in the chain-type C3MSV only one of these witnesses is violated. We find that, despite two-mode
entanglement, the fully-connected
topology admits no two-mode Gaussian steering ($\mathcal{G}^{i\to j}=0$) between any pair of physical modes; the steering resource is instead collective one-mode-versus-two steering $\mathcal{G}^{i\to jk}$, which is $\theta$-independent and grows with $r$. We analyze independent
vacuum losses and obtain critical transmittances for steering survival: under full symmetric loss at $r=0.5$, one-to-two collective steering disappears at $\eta\approx0.58$, whereas reverse two-to-one collective steering survives down to $\eta\approx0.502$ and the underlying two-mode
entanglement persists for all $\eta>0$. Finally, we revisit
photon subtraction using a normalized phase-space derivation. A
photon subtraction on a single physical mode does not generate Wigner negativity on another single mode, consistent with the absence of two-mode steering. Wigner negativity can instead be generated when Bob subtracts from the collective mode $(b+c)/\sqrt{2}$, with a loss threshold $\eta_c\approx0.667$ at $r=0.5$. These results distinguish pairwise and collective nonclassical resources in the FC-C3MSV and clarify the operational role of the complete-graph
topology.
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All authors Manjia Mai, Jifeng Sun, Teng Zhao, Ming Zhang, Liyun Hu
High Energy Physics (Theory)
Hypercomplex formulation of dissipative scalar electrodynamics and phase transitions
B.R. López-Raymundo and R. Cartas-Fuentevilla
A hypercomplex formulation of scalar electrodynamics is developed, in which dissipation emerges as an intrinsic dynamic property dictated by the extended local gauge
symmetry U(1)XSO(1,1). By constructing an effective free-energy functional, we derive the generalized Ginzburg-Landau equations and analyze the thermodynamic stability of the system. Our analysis of the
vacuum state up to the fourth order reveals that the constraint on the coefficients associated with the invariants prohibits the coexistence of mixed states, formally establishing the existence of a bicritical point. Consequently, upon crossing the critical temperature, the system is forced to undergo a discontinuous first-order phase transition. Furthermore, we demonstrate that the
hyperbolic symmetry induces a structural instability when the effective quartic couplings take negative values, rendering the free energy unbounded from below and creating asymptotic directions of instability.
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Applied Physics
Biodegradable, Millimeter-Scale Light-Emitting Sensors for Distributed Environmental Monitoring-Functional Pixie Dust
Zhiming Hu, Danzhen Zhang, Janghun Ko et al. (+24 more)
Methods for large-area, precise monitoring across natural environments are of growing interest due to pressing needs for sustainable management of rapidly increasing anthropogenic activities. Established approaches involve sparse spatial sampling and/or sequential measurements, while emerging techniques exploit miniaturized electronics or passive optical methods. Various constraints in scalability, costs, robustness, operational range and other factors create a need for alternatives. Here, we introduce a concept that overcomes many of these limitations through the combined use of chemically induced light emission and chemically responsive optical filter elements in millimeter-scale systems that we refer to as functional pixie
dust (fPD) sensors, designed specifically for monitoring natural water systems during nighttime to eliminate background optical interference and to enhance remote analysis. These floating devices act as Lagrangian tracers to follow surface flows and to simultaneously measure the concentrations of key chemical species along their trajectories. Optimized designs exploit environmentally compatible constituent materials that are also degradable through natural processes to benign end products, thereby eliminating the need for recovery. Spatially and spectrally resolved ratiometric measurement schemes ensure robust operation and ability to address practical requirements in range, operational lifetime, time response and sensitivity. Demonstrations include distributed measurements of pH, Hg2+, and NO2-, each of relevance to industrial discharge, toxic metal contamination, and nitrogen-rich runoff, adapted for static concentration gradients, flow-driven transport conditions, and outdoor aquatic settings. The results establish a framework for environmental sensing using degradable, self-powered microsystems capable of scalable deployment and remote readout.
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All authors Zhiming Hu, Danzhen Zhang, Janghun Ko, Haohui Zhang, Jiale Chen, Chanho Park, Jiatong Zhang, Qiuna Zhuang, Shiwei Xu, Xiaoran Yang, Dain Son, Taehoon Kim, Uikang Joo, Zhaojian Xu, Hyunsoo Kim, Richard Chai, Gwangmin Bae, Wooyoul Maeng, Qiong Wang, Sangmin Lim, Liangsong Zeng, Un-Seong Baik, Kaiqing Zhang, Liming Yuan, Yonggang Huang, Jin-Tae Kim, John A. Rogers
Quantum Physics
Spatial nonlocality imaging via metasurface
Jian Li, Zi-Mu Fan, Qing-Yuan Wu et al. (+7 more)
Bell nonlocality is both a defining signature of
entanglement and a key
quantum information resource. However, visualizing and certifying nonlocal correlations across a spatially multimode photonic field remains challenging due to the rapidly growing measurement cost of spatially resolved projective tests. To address this issue, we build a spatial nonlocality imaging scheme that directly reveals the spatial distribution of
quantum nonlocality by integrating a metasurface that performs parallel polarization projections with a
quantum-adaptive neural network. Spatially resolved Clauser–Horne–Shimony–Holt (CHSH) tests are realized over a 400-pixel biphoton field using an average of only 1.7 detected coincidence pairs per pixel per basis. This approach yields a nonlocality image that maps the two-dimensional spatial distribution of Bell violations across the optical field and reveals the target-state-dependent spatial
evolution of Bell violations. It provides a highly resource-efficient route to large-scale Bell certification and opens new possibilities for exploiting spatially multimode
entanglement in
quantum imaging,
quantum networking, and scalable photonic
quantum technologies.
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All authors Jian Li, Zi-Mu Fan, Qing-Yuan Wu, Wen-Kai Yu, Zhe Meng, Xing-Yan Fan, Wen-Hao Wang, Jie Ma, Xia Guo, An-Ning Zhang
Astrophysics of Galaxies
On the Separation Between the Brightest Cluster Galaxy and the Intracluster Light
Emanuele Contini and Sukyoung K. Yi
We present a model-based framework to define an aperture separation between the brightest cluster
galaxy (BCG) and the intracluster light (ICL). Using the intrinsic BCG and ICL components predicted by the semi-analytic model FEGA25, we determine, for each
halo, the aperture radius that minimizes the bias in the recovered ICL mass. The optimal radius is obtained by balancing the BCG
stellar mass lying outside the aperture with the ICL mass enclosed within it. At $z=0$, the optimal aperture in physical units increases with
halo mass approximately as $r_{\rm cut}\propto M_{\rm halo}^{0.28}$, close to the expected virial scaling. When expressed in units of the virial radius, the aperture becomes nearly independent of
halo mass, with $r_{\rm cut}/R_{\rm vir}\simeq 0.045$ at $10^{14}M_\odot$. Applying the resulting aperture prescriptions, we recover the intrinsic BCG mass to better than 8% (lowest percentile), while the ICL mass is recovered with median values very close to unity, and an average scatter of $\pm 3\%$. Extending the analysis to $z=1$ and $z=2$, we find that the mass trends remain similar, with the slope and intercept of $r_{\rm cut}/R_{\rm vir}$ that stay stable. Robustness tests show that the inferred aperture is most sensitive to the ICL concentration and BCG size, but the main trends are preserved. Our results provide a physically motivated aperture definition for connecting observational BCG–ICL measurements to intrinsic model components.
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High Energy Physics (Theory)
The next-to-next-to-leading order BFKL eigenvalue at odd conformal spin in planar N=4 super Yang-Mills: a reconstructed closed form, coefficient structure, and arithmetic
Alexander Prygarin and Claudelle Capasia Madjuogang Sandeu
We give the colour-singlet
eigenvalue of the three-loop BFKL kernel of planar N=4 super Yang-Mills in closed form at odd conformal
spin n. It splits into a holomorphic block and its conjugate, chi_2(n,nu)=(1/4)[F_n(z)+F_n(zbar)] with z=(|n|-1)/2+i nu, and the block is a finite combination of nested harmonic sums of one variable, rational functions and transcendental constants, of uniform transcendental weight five. At the two lower orders the sums are evaluated at the two conjugate points only. At three loops they are evaluated at every point of the integer ladder running from the reflected endpoint -zbar up to z, and one step beyond it, and for all but seven of the slots the coefficient at each rung is fixed by the two distances to the ends. Summing over the one-variable functions before summing along the ladder replaces the rules of those slots by one function of one variable under each ladder weight. The remaining seven are carried by a sum along the ladder whose summand moves with the summation index. All forty-seven coefficient slots follow from rules uniform in the conformal
spin at every odd n>=3, with no per-
spin coefficient tabulated in the definition; the n=1 boundary block is supplied separately. Those rules are a reconstruction from the computed
spins, exact at every one of them, verified over the range n<=99 and at the holdout
spin n=101, and not proved at arbitrary odd n. Along nu=0 the intercepts agree with the
Quantum Spectral Curve values at every computed odd
spin through n=91. That comparison tests the three-loop integrand and the reduction performed here together, at one point of each
spin, and for most of those
spins it is the first comparison of its kind.
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General Relativity and Quantum Cosmology
Massive Compact Stars Beyond the General Relativity Limit in Finslerian Gravity: A Possible Explanation for the GW190814 Secondary
Praveen J, Rajesh Kumar, Sadaf Fatima et al. (+1 more)
The existence of an upper mass limit for compact
stars is one of the fundamental predictions of general relativity (GR), with important implications for the outcome of compact binary mergers and the nature of the proposed
neutron star black hole mass gap. The LIGO Virgo collaboration announced the discovery of a compact binary merger, GW190814, containing a compact
star with mass 2.5 to 2.67 $M_\odot$ [R. Abbott et al.(2020) ApJ Lett., 896, L44], which provided an exciting new stimulus to the ongoing debate on whether a gap exists between the maximum mass of NS and the minimum mass of black hole. Such GW detection has also challenged conventional
stellar models and renewed interest in exploring whether modified theories of
gravity can accommodate such ultra-massive compact objects without invoking black hole formation. The present work investigated the structure and physical properties of compact
stars within the framework of Finslerian
gravity, employing the Heintzmann IIa gravitational potentials and showed that the our model can substantially enhance the maximum mass of compact
stars upto $2.67 M_{\odot}$, thereby offering a plausible explanation for massive compact objects such as the secondary component of GW190814. In addition, the moment of inertia is found to increase, indicating stronger rotational support and a redistribution of the internal mass profile. The analysis focuses on key astrophysical observables, including the mass radius and moment of inertia mass relations, and a detailed comparison with the GR counterpart is performed. Assuming a linear equation of state, we construct a class of physically viable anisotropic
stellar models and analyze their behavior under the influence of Finslerian corrections. The physical viability of the model is rigorously tested through stability criteria.
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All authors Praveen J, Rajesh Kumar, Sadaf Fatima, S K Narasimhamurthy
High Energy Physics (Theory)
The next-to-next-to-leading order BFKL eigenvalue at odd conformal spin in planar N=4 super Yang-Mills
Alexander Prygarin and Claudelle Capasia Madjuogang Sandeu
We give the next-to-next-to-leading order color-singlet BFKL
eigenvalue of planar N=4 super Yang-Mills at odd conformal
spin n in closed form. At the two lower orders the known expressions contain nested harmonic sums only at the two conjugate points z=(|n|-1)/2+i nu and zbar. At three loops the sums are evaluated on a ladder of integer-shifted arguments from the reflected point -zbar up to z, with one point past it, the coefficient at a rung fixed by its two distances to the ends. Seven families are the exception, their coefficients written through ladder sums whose summand shifts with the summation index. For one of the seven the coefficient lies outside the fixed-coefficient
algebra of nested harmonic sums of the two distances, an arithmetic obstruction in the denominators. That exclusion reaches the
eigenvalue coefficient only through an agreement of rule and coefficient verified and not proved. Rules uniform in the conformal
spin produce all forty-seven families at every odd n>=3; no per-
spin coefficient is tabulated in the closed form, and the n=1 boundary block is supplied separately. Those rules are a reconstruction from the computed
spins, exact at every one of them, verified over the range n<=99 and at the holdout
spin n=101, and not proved at arbitrary odd n. Each atom-table coefficient is a rational combination of 1, pi^2 and
zeta_3, coefficient and atom together carrying transcendental weight five. Along nu=0 the intercepts match the
Quantum Spectral Curve values at each computed odd
spin through n=91, the extent of those values. The comparison tests the integrand and the reduction together at one point of each
spin, for most of them for the first time. Away from that line the closed form gives the collinear behavior of the block uniformly in the
spin, which the intercepts alone do not fix.
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Mathematical Physics · Cross-listed from q-bio.NC
Exploring Brain Networks Using Noninvasive Electrophysiological Measurements: Methods and Applications
Richard Leahy and Takfarinas Medani
Electroencephalography (
EEG) and magnetoencephalography (MEG) provide noninvasive measurements of
brain activity with millisecond temporal resolution, enabling the investigation of functional and effective interactions within large-scale
brain networks. This chapter presents a comprehensive overview of the methodological foundations and practical workflows for
EEG/MEG-based
brain network analysis. We first review the physical principles underlying
EEG and MEG, emphasizing their complementary strengths and limitations. We then describe the forward and inverse problems, including subject-specific head modeling, source reconstruction techniques, and the importance of accurate anatomical modeling for reliable source localization. Strategies for mitigating volume conduction and signal leakage are discussed, together with best practices for source-space connectivity analysis. The chapter reviews widely used functional and effective connectivity measures, including coherence, phase synchronization metrics, amplitude envelope correlation, Granger causality, dynamic causal modeling, and transfer
entropy, highlighting their assumptions, advantages, and limitations. Modern end-to-end analysis pipelines are presented, with particular emphasis on Brainstorm and complementary open-source software for reproducible
EEG/MEG research. Finally, we discuss emerging approaches, including time-varying connectivity, cross-frequency interactions, and network-based analyses, illustrating how noninvasive electrophysiology contributes to understanding
brain organization in health and disease. The chapter provides both conceptual foundations and practical guidance for researchers and advanced students seeking to map and interpret human
brain networks using
EEG and MEG.
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Optics
Crystal orientation enables near-unity nonlinear circular dichroism in resonant metasurfaces
Chi Wang, Dmitrii Gromyko, Polina Pantiukhina et al. (+2 more)
Achieving near-unity nonlinear circular dichroism (CD) typically requires
geometric symmetry breaking, making it challenging to combine helicity selectivity, resonant enhancement, and structural simplicity. We show that
crystal orientation enables near-unity third-harmonic (TH) CD in highly symmetric resonant metasurfaces formed by a square
lattice of circular holes in a cubic nonlinear material. Under circularly polarized excitation, strong near-field components of both helicities enabled by the rotational
symmetry of the metasurface open two
symmetry-allowed in-plane TH generation pathways.
Crystal orientation controls their nonlinear coupling, selectively enabling destructive interference for one incident helicity. Our nonlinear temporal coupled-mode theory identifies the conditions for near-unity CD, reveals the distinct roles of pump and TH resonances, and explains the fourfold and eightfold
crystal-orientation dependence. Across silicon, germanium, and diamond, we obtain resonantly enhanced TH CD exceeding 99% in the near-infrared, establishing
crystal orientation as a design degree of freedom for nonlinear CD in highly symmetric metasurfaces.
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All authors Chi Wang, Dmitrii Gromyko, Polina Pantiukhina, Lin Wu, Kirill Koshelev
Materials Science
CuCrZr heat-sink irradiation performance reveals new challenges for thermonuclear fusion reactors
Thomas Barzic, Anna-Carina Seitlinger, Christoph Frühwirth et al. (+10 more)
Commercial fusion energy requires materials that survive intense
neutron bombardment whilst extracting extreme heat loads for conversion to electricity. The CuCrZr
alloy, the leading heat-sink material for fusion reactors, derives its strength from a fine dispersion of nano-precipitates formed during
prime-ageing heat-treatment. Whether this precipitation-hardening strategy can withstand fusion-relevant irradiation remains untested. Here we show, combining in situ transmission electron microscopy under heavy-ion irradiation and He implantation with thermodynamic and transmutation modelling, that the hardening precipitates dissolve under two opposing kinetic regimes: ballistic dissolution dominates at low temperatures, whilst dissolution and re-precipitation dominate at high temperatures. Although the accelerated dose rates inherent to ion irradiation shift the balance between ballistic mixing and thermal back-
diffusion relative to reactor conditions, precipitate degradation at both kinetic extremes indicates that the
prime-aged microstructure is unlikely to remain unaltered under prolonged
neutron exposure. He bubbles and Kr-rich voids nucleate once vacancies become mobile, and transmutation over five service years irreversibly redirects the
alloy chemistry towards Ni-Zr intermetallics. These three independent mechanisms converge to challenge the strategy on which CuCrZr performance depends, suggesting that the long-term performance of age-hardenable Cu-based heat-sink
alloys in fusion reactors warrants further assessment. Our findings reveal a new materials challenge for fusion reactor design and commercialisation: the need for new Cu-based heat-sink
alloys able to retain engineered strength whilst their chemistry is irreversibly rewritten - thermodynamically and ballistically - by the fusion
neutron spectrum.
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All authors Thomas Barzic, Anna-Carina Seitlinger, Christoph Frühwirth, Edward McDonald, Jing Tang, Jonathan A. Hinks, Alexandr Zinovev, Dmitry Terentyev, Stefan Luidold, Cláudio G. Schön, Enrique Jimenez-Melero, Stefan Pogatscher, Matheus A. Tunes
Chemical Physics
Disorder-induced Dark States Line Shape in Pump-Probe Spectroscopy of Polaritons
Luca Nils Philipp, Julian Lüttig and Roland Mitrić
The formation of hybrid light–matter states called polaritons provides a route to shape the photophysics and photochemistry of molecules. Accordingly, the dynamics of polaritons following photoexcitation is extensively studied. In particular, the role of the dark state
manifold in such processes remains unclear. Here, we investigate the line shape of pump-probe spectra of polaritons emerging at the dark states energy under the influence of disorder. Previously, we already investigated the pump-probe line shapes of polaritons in a disorder-free model and identified distinct signatures of relaxation into dark states, thus providing an indirect probe of this relaxation. Since the transition dipole moment of dark states vanishes in a disorder-free model, they cannot be directly probed. However, dark states acquire small transition dipole moments as soon as disorder is explicitly included in the model enabling them to be directly probed. In this work, we demonstrate that the inclusion of the relaxation to dark states and disorder leads to the
evolution of the spectral shape at the DS energy from a derivative-like into an absorptive line shape. Furthermore, we investigate the dependence of the line shape on the disorder strength and its asymptotic scaling for a large number of coupled molecules. Our results demonstrate that probing dark states can help to single out the polaritonic response from the total signal.
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