Quantum Physics
The Cost of Removing Tunability in Quantum Data Re-Uploading
Anthony Yuezhang Liu and Lirandë Pira
Fixed encoding data re-uploading
quantum circuits provide a striking example of universality emerging from a highly constrained architecture. However, universality alone is insufficient for assessing the theoretical and practical value of fixed and tunable upload
circuits. The resource cost of removing tunability remains poorly understood. In this work, we establish quantitative depth-error scaling for approximating tunable upload
circuits with fixed upload
circuits. We show that a tunable upload
circuit can be approximated by a fixed upload
circuit using depth \( D = O_\sigma\!\left[(\log(1/\varepsilon))^\sigma\right] \) for every \(\sigma>1\), with a target dependent constant overhead, thereby improving the previously known
polynomial dependence on \(1/\varepsilon\) with the same overhead. Our proof is based on an auxiliary extension approximation mechanism that combines Gevrey class construction, Jackson's
theorem and generalized
quantum signal processing
theorem. Thus, the expressive power lost by removing tunability can be recovered using only polylogarithmic growth in
circuit depth with a target dependent constant overhead. We further identify a periodic mismatch obstruction intrinsic to fixed upload approximations and use Turán-Nazarov inequalities to prove logarithmic lower bounds \( D = \Omega(\log(1/\varepsilon)) \) for the approximation of mismatch class target tunable upload
circuits. Conceptually, our analysis reveals two structural mechanisms underlying approximation in fixed upload architectures: auxiliary extensions and mismatch obstructions. These results provide a quantitative understanding of how expressivity is transferred from tunable frequencies into
circuit depth, and suggest a broader framework for studying approximation complexity in
quantum signal processing and related
quantum learning models.
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Cosmology and Nongalactic Astrophysics
The Impact of Dense RM Grids on the Study of Intra-cluster and Intra-group Magnetic Fields
Francesca Loi, Valentina Vacca, Shane P. O'Sullivan et al. (+8 more)
The presence of diffuse
radio sources in
galaxy clusters and the recent discovery of polarized signals associated with the tails of a jellyfish
galaxy indicates that intra-cluster/intra-group
magnetic fields can influence the physics of these environments and the
evolution of the embedded
galaxies. A better reconstruction of the properties of such fields is therefore fundamental to understand in detail the physical processes in
galaxy groups and clusters and the
evolution of the embedded sources. The SKAO represents a great opportunity to perform these studies through the analysis of the so-called rotation measure (RM) grid, since polarization properties of
radio sources are modified by the intervening
magnetic field. In this manuscript, we illustrate the prediction on the density of the RM grid considering the SKA-mid polarization survey planned by the SKA Magnetism Science Working Group. Moreover, we describe how it is possible to measure intra-cluster/intra-group
magnetic fields with the RM grid. Eventually, we quantify the improvement in the precision and accuracy of the
magnetic field measurements compared to what is achievable with current surveys such as the POSSUM survey.
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All authors Francesca Loi, Valentina Vacca, Shane P. O'Sullivan, Craig Anderson, Chiara Stuardi, Federica Govoni, Matteo Murgia, Annalisa Bonafede, Ettore Carretti, Filippo M. Maccagni, Tessa Versnstrom
Cosmology and Nongalactic Astrophysics
Slay the Shear: A Unified Statistical Framework for Weak Gravitational Lensing Shear Estimation
Shurui Lin, Xiangchong Li and Xin Liu
Weak gravitational
lensing shear measurements are fundamentally limited by shape noise arising from the intrinsic diversity of
galaxy morphologies. Upcoming surveys such as Rubin/LSST, Euclid, and Roman demand more flexible, statistically optimal approaches that can fully exploit high-dimensional image information. In this work, we develop a unified theoretical framework for shear estimation that connects classical response-based methods, shape noise, and modern machine-learning
estimators through the concept of the score function – the gradient of the image likelihood with respect to shear. We show that, for a general
spin-2 ellipticity definition, the ensemble shear response corresponds to an inner product between the
estimator and the score function, and that the score provides the minimum-variance unbiased shear
estimator. By incorporating response into the classical inverse-variance weight, we prove that the response-weighted inverse-variance weight is a general shape-noise-minimizing weight, independent of the intrinsic shape distribution. Furthermore, we propose Response-weighted Denoising Score Matching (RDSM) that exploits the remaining structure to reduce shape noise by ${\sim}17.5\%$ relative to moment-based methods at LSST 10-year depth while maintaining a multiplicative shear estimation bias below $2\times 10^{-3}$. Our result clarifies the optimality of existing calibration techniques while revealing a principled pathway for constructing improved
estimators via nonlinear shape transformations and learned representations.
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Astrophysics of Galaxies
A 3D tomography of the Local Bubble with SKA-Low
Xiaohui Sun, George Heald and Andrea Bracco
We know we reside in the Local Bubble (LB), but we know little about the magnetized gas inside the LB. The SKA-Low with more than half of the total number of stations distributed within 1 km distance provides enough short baselines and thus great surface brightness sensitivity. An SKA-Low polarization survey covering the frequency range of 50-350 MHz will deliver high-sensitivity and high-resolution images of diffuse polarized emission that originates from the local interstellar medium (ISM) and is probably related with the LB. Such a survey will also determine precisely the rotation measures (RMs) for the polarized structures using RM synthesis. These will allow us to reveal the 3D structure of the magnetized medium in the LB and to understand how the LB forms and evolves.
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Quantum Physics
Controlling radiative dynamics of a giant $\Lambda$-type atom via interference induced by the vacuum of a waveguide
Ci-Ming Deng, Ge Sun, Jing Lu et al. (+1 more)
We investigate the dynamics of a $\Lambda$-type
giant atom (GA) whose both transition coupled to the guided modes of a one-dimensional (1D) waveguide at two spatially separated points with the GA initially excited and the electromagnetic (EM) modes of waveguide in
vacuum. The spontaneous emission properties of this GA is investigated by solving the delay-differential equation for the amplitude of the 3GA in its excited state. Signatures of non-Markovian behavior is manifested in a population trapping in the excited state of the GA in the regime where the distance $d$ of the coupling points is smaller or comparable to the coherent length $L$ characterizing the width of the emitted wave packet. And an exact Markovian dynamics is also found when $d\geq L$ via the inference by adjusting the energy spacing and the inherent time delay besides the complex phases in the atom-light coupling, matching the behavior of a small atom coupled to a waveguide.
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All authors Ci-Ming Deng, Ge Sun, Jing Lu, Lan Zhou
Cosmology and Nongalactic Astrophysics
Weak Lensing with SKAO: Cosmic Shear Cosmology
Ian Harrison, Roberto Ingrao, Stefano Camera et al. (+4 more)
We discuss the power of weak gravitational
lensing surveys with the SKAO in constraining cosmological parameters and the properties of
radio star-forming
galaxy samples. As well as reviewing progress to date on
cosmic shear in
radio experiments, we show forecasts for parameter constraints using the Mid
telescope both alone and in cross-correlation with contemporaneous optical surveys. By selecting a sample of resolved, high-
redshift star-forming
galaxies in Band 2, surveys with the AA4 configuration will be capable of measuring the growth of structure on large scales in the Universe through the effect of weak gravitational
lensing on their shapes. Assuming the high fidelity reconstruction of such
galaxy shapes to be possible, we find that SKAO will measure the $S_8$ structure formation parameter to a level of $5\%$ alone and $3\%$ in full combination with either LSST or the Euclid satellite. These measurements will be highly important due to their radically different sensitivities to key weak
lensing systematics, both instrumental and astrophysical, and as such provide a vital robustness test to a pillar of modern cosmological measurements.
Radio surveys also provide unique and potentially game-changing information in the form of polarisation and
galaxy kinematics, which allow the cleaner separation of
lensing from intrinsic
galaxy shapes and can increase statistical power by factors $\sim5$-$10$.
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All authors Ian Harrison, Roberto Ingrao, Stefano Camera, Catherine Cress, Mamta Pandey-Pommier, Ziad Sakr, Cora Uhlemann
Astrophysics of Galaxies
The magnetic field in the Milky Way Galaxy: from large to small scales
Xiaohui Sun, Jennifer West, Marijke Haverkorn et al. (+6 more)
The Milky Way is the
galaxy in which we can study its
magnetic field to the finest details, providing an ideal laboratory to understand the fundamental questions: how
magnetic field is generated and evolves, and how it influences other components in the
Galaxy. An SKA-Mid polarization survey will produce an all-sky rotation measure (RM) grid with a density of about 100 per square degree, which is approximately two orders of magnitude larger than what is currently available, and produce total intensity, polarized intensity, and RM all-sky images of diffuse emission covering scales from about 10 arcseconds upward after combination with single-dish observations. The dense RM grid and images of diffuse emission will allow us to determine the most complete picture of the
magnetic field in the southern
Galactic hemisphere from large to small scales.
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All authors Xiaohui Sun, Jennifer West, Marijke Haverkorn, Andrea Bracco, Anna Ordog, Sui Ann Mao, Yik Ki Ma, Wenhui Jing, Thiem Hoang
Astrophysics of Galaxies
The OTELO Survey: The main sequence of low-mass galaxies
Bernabé Cedrés, Jordi Cepa, Carmen P. Padilla–Torres et al. (+15 more)
This paper describes the relationship between the
star formation rate and the
stellar mass, the so-called main sequence (MS), of low-mass
galaxies at three different
redshifts from the OTELO survey. In particular, we study Halpha at z=0.38, [OIII] at z=0.83, and [OII] at z=1.43 emission line
galaxies (ELGs). This is done to characterise the properties of low-mass ELGs. We fitted the spectral energy distribution (SED) of each emitter and obtained the
stellar masses, the total infrared luminosity, and the
star formation rate. We found that 100% of the Halpha emitters and about 90% of the [OIII] and [OII] emitters are low-mass
galaxies (< 1E10M_sun). We generated a MS for each
redshift regime, employing all
galaxies and binning them in
stellar mass. We obtained the parameters of the fit (turnover mass and slope of the low-mass regime) and compared them to results from the literature. We found that the colour-magnitude method employed to select ELGs leaves out a significant number of them. We also found that the whole sample contains few luminous infrared
galaxies and no ultra-luminous infrared
galaxies. We also found that the lack of infrared constraints in the input SEDs may generate problems when determining the total infrared luminosity. When comparing the MS obtained for our sample of low-mass ELGs with those from the bibliography, we found, in general, very good agreement. We can consider the MS to be almost the same for the relatively unexplored regime of low-mass
galaxies. However, the turnover mass obtained by this work is higher for all
redshifts compared with the ones from the literature. We suggest that this is an effect of the different methods and samples used in the generation of the MS compared to those of the bibliography.
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All authors Bernabé Cedrés, Jordi Cepa, Carmen P. Padilla–Torres, Ángel Bongiovanni, Miguel Cerviño, José A. de Diego, Jakub Nadolny, Simon B. De Daniloff, Mauro González–Otero, Monica I. Rodríguez, Jesús Gallego, Mirjana Pović, Maritza A. Lara–López, J. Ignacio González–Serrano, Miguel Sánchez–Portal, Ana María Pérez–García, Ricardo Pérez–Martínez, Emilio J. Alfaro
Instrumentation and Methods for Astrophysics
argosim: a Python package for radio interferometric simulations
Ezequiel Centofanti, Emma Ayçoberry, Samuel Farrens et al. (+4 more)
In this paper, we present argosim, a Python package for simulating
radio interferometric observations. The argosim package is modular, lightweight and compatible with all major operating systems. Its computational backend is written in JAX, which allows for greatly accelerated performance as well as the advantage of being fully differentiable. We detail the main argosim modules and describe how to use them to generate an observation, from the
antenna positions to the cleaned image. The package is a fully open-source project, and its code is publicly available on GitHub.
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All authors Ezequiel Centofanti, Emma Ayçoberry, Samuel Farrens, Samuel Gullin, Manal Bensahli, Jean-Luc Starck, John Antoniadis
Fluid Dynamics
VesNet: Neural network accelerated solver for simulating Stokesian vesicle suspensions
Shan Zhong, Gokberk Kabacaoglu and George Biros
Numerical simulation of deformable particle suspensions in Stokes flow is computationally expensive due to nonlinear fluid-structure interactions, evolving interfaces, and multiscale hydrodynamics. We present VesNet, a hybrid framework that accelerates two-dimensional vesicle suspension simulations by approximating vesicle self interactions, including background flow coupling and short-range lubrication forces, while retaining conventional modules for boundary reparameterization and far-field hydrodynamics. A GPU-accelerated implementation achieves over 100x speedup compared to a multithreaded MATLAB CPU boundary integral solver and about 5x relative to its GPU counterpart. VesNet accurately captures key dynamics, including single-vesicle phase behavior, pair interactions, and large-scale suspensions in Taylor-Green and Poiseuille flows, enabling efficient simulations of thousands of vesicles on modest computational resources.
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General Relativity and Quantum Cosmology
Galactic microlensing by acoustic Schwarzschild black holes
G. F. Akhtaryanova, R. Kh. Karimov, U. K. Khidirov et al. (+1 more)
This work explores the application of acoustic black holes as a novel class of lenses in
Galactic microlensing, potentially representing dark matter
halo objects. While sharing key features like an event horizon, their underlying fluid-dynamical description differs from the
vacuum solutions of Einstein's equations, suggesting potentially distinct observational signatures. This work investigates these distinctions by calculating the
galactic microlensing predictions for acoustic black holes and comparing them to the standard Schwarzschild case. Using the observed parameters of known black hole candidates (Cygnus X-1, A0620-00, GRO J1655-40) as illustrative lenses, we demonstrate that the acoustic black holes tuning parameter $\xi $ significantly alters key observables. Our results show that an increase in $\xi $ leads to a larger Einstein ring radius, a longer event duration, and a higher peak magnification in the microlensing Paczyński light curves. Furthermore, we find that the microlensing event rate is enhanced for acoustic black holes compared to their Schwarzschild counterparts, with the probability of detection growing with $\xi$. These findings establish
galactic microlensing as a promising astrophysical channel for constraining analogue
gravity metrics, with the primary effects being potentially detectable in the statistical analysis of current and future microlensing survey data.
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All authors G. F. Akhtaryanova, R. Kh. Karimov, U. K. Khidirov, R. N. Izmailov
Chemical Physics
Developing fast, accurate and spin pure calculations of organic diradical electronic structure
Joseph T. Kielty, Hugh G. A. Burton and Timothy J. H. Hele
Organic diradical molecules have emerged in recent years as highly promising candidates for next generation optoelectronic and
quantum information technologies. As efforts continue to synthesise diradicals with unique photophysical properties, developing our theoretical understanding of their complex electronic structure is crucial to enable rational design strategies. However, existing computational tools struggle to properly describe the multi-reference character of diradical electronic states while also preserving a low computational scaling that enables fast calculations on large emissive diradicals. This work presents a new computational method, termed Diradical Extended Restricted Open-shell PPP (D-ExROPPP) theory, which we show yields accurate and
spin-pure electronic states at a very low computational cost relative to existing approaches. This is achieved by implementing a novel,
spin-adapted configuration interaction approach within the semi-empirical Pariser-Parr-Pople framework. D-ExROPPP is then used to study the electronic structure of three prototypical organic diradicals, and benchmarked against results from computationally intensive, post-Hartree-Fock methods. Excitation energies for these molecules are predicted that show a similar level of accuracy as high-level ab-initio calculations, while requiring up to five orders of magnitude less computational time. We further apply D-ExROPPP to a number of recently reported stable, emissive, organic diradicals. In the majority of cases, electronic transitions measured in experimental UV-vis spectra are reproduced with qualitative accuracy and the
spin states involved can be reliably assigned. Together, these results establish D-ExROPPP as a promising new tool for efficiently predicting and interpreting the photophysics of organic diradical molecules.
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Materials Science
A topology-tuned pressure valve across the isoreticular RHO zeolite family
Salvador R. G. Balestra, Antonio Rivas-Blanco, Said Hamad et al. (+1 more)
The isoreticular index of the eight-member embedded RHO zeolite hierarchy operates as a phenomenological design knob that tunes the mechanical critical pressure of the framework valve from $\sim 0.94$ GPa for parent RHO down to a predicted $\lesssim 0.03$ GPa for the largest member PST-28, more than an order of magnitude lower across a single family of synthesizable nanoporous solids. The molecular-valve effect that defines zeolite RHO (a reversible centric-to-acentric phase transition triggered by water, gas pressure, or mechanical loading) is shown here to be not a peculiarity of the smallest member but a generic property of the whole hierarchy, with a critical pressure that decays exponentially with the isoreticular order $k$. Combining
lattice dynamics, full elastic-constant tensors, and finite-temperature free-energy reconstructions within a classical core-shell description of the pure-silica frameworks (independently validated against r$^2$SCAN+rVV10 density-functional theory on $G_1$ and $G_2$), we find that the entire family is well described by an effective mean-field Landau picture in which the framework distortion couples quadratically to the volumetric strain. We emphasise that $p_c$ is a mechanical (hydrostatic) critical pressure of the bare pure-silica framework, used as a proxy for the intrinsic framework softness and for the cation- and dehydration-driven response of the real aluminosilicates; it is not a gas-adsorption pressure. The exponential extrapolation places $p_c(G_6\text{-}G_8) \lesssim 0.1$ GPa (model-dependent band $0.03$-$0.15$ GPa), identifying the higher-order members as the softest, most stimuli-responsive frameworks of the hierarchy; whether this intrinsic softness translates into guest-driven switching at low gas activities will depend on the Al distribution, extra-framework cations and adsorbed molecules, and remains to be tested experimentally.
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All authors Salvador R. G. Balestra, Antonio Rivas-Blanco, Said Hamad, A. Rabdel Ruiz-Salvador
Atomic Physics
Broadband Rydberg Atomic Microwave Sensing with 44.6$\,$MHz Instantaneous Bandwidth
Yuhan Yan, Xuejie Li, Jinyin Wan et al. (+6 more)
Rydberg atoms have become a promising novel type of microwave sensor due to their excellent physical properties – broad frequency coverage and large electric dipole moments. High sensitivity and broad instantaneous bandwidth are two indispensable requirements for deployable Rydberg microwave sensors. However, enabling broadband operation while retaining high sensitivity has been a longstanding barrier limiting their applications. We propose and experimentally demonstrate a Rydberg microwave sensor whose instantaneous bandwidth is significantly enhanced via an auxiliary microwave field. By finely modulating the Rydberg energy levels with this field, we broaden the bandwidth substantially while retaining the sensor's inherent high sensitivity. An instantaneous bandwidth of 44.6$\,$MHz ($\pm$22.3$\,$MHz) with a sensitivity of 225.7$\,$nV$\,$cm$^{-1}\,$Hz$^{-1/2}$ is realized in a thermal \(^{87}\)Rb vapor with the local microwave frequency of 16.03$\,$GHz. Our work delivers concurrent broad instantaneous bandwidth and high sensitivity for Rydberg microwave sensors, paving a technically viable path for their practical deployment in broadband microwave metrology, radar, and wireless communication.
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All authors Yuhan Yan, Xuejie Li, Jinyin Wan, Xing Xia, Haojie Zhao, Binghong Yu, Jianliao Deng, Huadong Cheng, L. Q. Chen
High Energy Physics (Phenomenology)
Current-dependent SU(3)-flavor breaking in hidden-heavy $0^{--}$ tetraquark spectroscopy
Bing-Dong Wan, Ming-Yang Yuan, Si-Yu Liu et al. (+2 more)
We investigate SU(3)-
flavor-breaking effects in hidden-heavy tetraquark channels with the exotic
quantum number $J^{PC}=0^{--}$, focusing on the dependence of the extracted mass shifts on the interpolating-current structure. Using four local color-octet–octet currents within QCD sum rules, we retain the explicit strange-
quark mass and strange condensate contributions in the operator product expansion through dimension eight. By comparing the strange and nonstrange sectors within the same current basis, we obtain hidden-charm-strange mass estimates between 4.37 and 4.79 GeV and hidden-bottom-strange masses between 10.85 and 11.19 GeV. The central charm-sector mass shifts are approximately 40 and 70 MeV for the hidden-
flavor-like currents, compared with 190 and 220 MeV for the open-
flavor-like currents. The bottom sector exhibits a smaller spread in the corresponding shifts. These results suggest a current-dependent SU(3)-breaking response within the adopted sum-rule framework. The predicted mass associated with one open-
flavor-like current also overlaps the $D_s^*\bar D_{s1}(2536)$ threshold region within uncertainties. Our analysis provides complementary strange-sector spectral information while leaving the physical-state composition unresolved.
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All authors Bing-Dong Wan, Ming-Yang Yuan, Si-Yu Liu, Jun-Hao Zhang, Yan Zhang
Instrumentation and Methods for Astrophysics
Gravitational Light Deflection with SKA-VLBI and Its Application to Precision Tests of General Relativity
Y. J. Li, J. J. Li, Z. H. Lin et al. (+4 more)
Experimental test of general relativity remains an ongoing endeavour.
Radio astrometry provides a vital tool for precisely measuring the light deflection caused by the Sun, testing general relativity, and discriminating between gravitational theories. The best accuracy for the post-Newtonian relativistic parameter, $\gamma$, achieved with very long baseline interferometry is $9 \times 10^{-5}$. With 300-sec integration, SKA-VLBI can achieve a sensitivity of $\sim$15 $\mu$Jy at 15 GHz over a bandwidth of 0.256 GHz. This enables detection of $\sim$36 extragalactic
radio sources per square degree with flux densities of $\sim$1.5 mJy, and potentially detecting in-beam
radio sources. Single-epoch SKA-VLBI observations may achieve an astrometric precision of $\sim$2 $\mu$as. Utilising the Sun as a gravitational lens, 10-epoch positional tracking of extragalactic sources could improve $\gamma$ accuracy to $\sim$10$^{-7}$. Even with Jupiter as a lens, SKA-VLBI can measure $\gamma$ to $\sim$10$^{-4}$. Critically, it may conduct the first measurement of quadrupolar deflection of light caused by Jupiter, determining the physical oblateness of Jupiter, $J_{\mathrm{2, J}}$, to within $\sim${}$10^{-3}$. These advances are expected to rigorously test and improve gravitational theories or high-order parameterized post-Newtonian formalisms, while laying the foundations for (sub)$\mu$as astrometry.
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All authors Y. J. Li, J. J. Li, Z. H. Lin, D. J. Liu, Y. W. Dong, C. J. Hao, Y. Xu
High Energy Astrophysical Phenomena
Compact Objects Revealed by SKA and SKA-VLBI
Z. H. Lin, Y. J. Li, C. J. Hao et al. (+4 more)
Compact objects represent a crucial interdisciplinary frontier between astronomy and fundamental physics.The SKA/SKA-VLBI, with exceptional sensitivity (at $\mu$Jy levels) and ultrahigh positional precision (at $\mu$as levels), will enable direct, precise measurements of orbital dynamics in compact objects including black holes and
neutron stars. This facility is expected to achieve at least three breakthroughs: (1) Developing effective methodologies for detecting and identifying black hole-
neutron star binaries to construct observational catalogues, thus advancing investigations into the equation of state of ultra-dense
nuclear matter and strong-field relativistic effects; (2) Determining critical parameters such as orbital elements and component masses in compact binaries, yielding insights into
stellar structures and evolutionary mechanisms under extreme conditions; (3) Identifying intermediate-mass black holes and measuring their masses to deepen understanding of black hole formation and
evolution.
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All authors Z. H. Lin, Y. J. Li, C. J. Hao, J. J. Li, Y. W. Dong, D. J. Liu, Y. Xu
Optics
Pseudo-spectral frequency-domain method with background field decomposition and Green's function preconditioner for electromagnetic scattering problem in EUV lithography
Seungjin Lee, Werner Gillijns and Doyun Kim
We provide an accelerated computational framework to solve electromagnetic scattering problems in planarly layered media arising from extreme ultraviolet (EUV) lithography. To achieve this, we reformulate the EUV scattering problem into a scattering problem on a homogeneous background, in which the electromagnetic contribution of the layered media is captured by a recursively updated reflection of the layered stack. The system is numerically solved by employing the pseudo-spectral frequency-domain method paired with an iterative solver, whose iterative convergence is expedited by a free-space Green's function preconditioner. The proposed framework is evaluated on EUV mask geometries and multilayer mirror stacks, demonstrating a significant speedup over the conventional pseudo-spectral frequency-domain method.
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Soft Condensed Matter
Mode-locking in a colloidal ring driven by power-modulated optical tweezers
Muyang Huang, Pik-Yin Lai and Xiaoguang Ma
Particles and clusters moving across real-space periodic potentials can become locked to discrete directions or orientations due to competing
symmetries. Here, we demonstrate an analogous locking phenomenon within a synthetic frequency space. We drive ring-shaped colloidal clusters using a circular optical tweezer array, where power modulation of the traps generates coexisting, distinct potential waves. Relative displacements between the cluster and these waves trace zigzag trajectories across a synthetic two-dimensional
lattice, mirroring directionally locked motion in real-space periodic potentials. By tuning the relative wave amplitudes, both the cluster's direction in synthetic space and its velocity in real space exhibit discrete plateaus, both governed by square-
lattice symmetry. Furthermore, the formation of superlattices between the particles and potential wave minima mirrors the characteristic features of kinetically locked two-dimensional clusters, demonstrating the capability to explore driven cluster dynamics within higher-dimensional potentials using lower-dimensional setups. Our findings establish new strategies for controlling transport of particle clusters via power-modulated
laser tweezers.
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Cosmology and Nongalactic Astrophysics
Probing the Fundamental Nature of Particle Dark Matter
Marco Regis, Aritra Basu, Geoff Beck et al. (+7 more)
Understanding the fundamental nature of dark matter (DM) is one of the most significant scientific challenges of our time. A compelling hypothesis is that DM consists of a new, yet-to-be-discovered particle. Among the leading candidates are weakly interacting massive particles (WIMPs) and
axion-like particles (ALPs), both of which can be investigated using observations with the SKA
telescopes. In this chapter, we review the search for particle DM through
radio observations, summarizing the current state-of-the-art and presenting forecasts for the SKA-Low and SKA-Mid
telescopes in the AA4 baseline design.
Radio searches for WIMPs focus on detecting synchrotron radiation originating from the products of DM annihilation using continuum observations. Competitive constraints on sub-TeV WIMPs have already been derived using SKA precursors looking at
dwarf galaxies,
galaxy clusters, and the Large Magellanic Cloud. We discuss how the superior continuum sensitivity of the SKA
telescopes will allow us to progressively close in on the WIMP parameter space. The ALP signal arises from its decay or conversion into
photon(s), which typically consists of a nearly monochromatic signature, and from rotation of polarization angles of
photons interacting with ALPs. We demonstrate how the spectral resolution, line sensitivity, and polarimetry of the SKA AA4
telescopes can be leveraged to constrain the ALP-
photon coupling.
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All authors Marco Regis, Aritra Basu, Geoff Beck, Gianni Bernardi, Paolo Marchegiani, Dominik J. Schwarz, Marco Taoso, Elisa Todarello, Emma Tolley, Cora Uhlemann
Plasma Physics
Numerical thermalization in $n$-D particle-in-cell simulations
R. M. Park, C. H. Moore and S. D. Baalrud
The particle-in-
cell (PIC) simulation method is often understood to solve the collisionless Vlasov equation due to the finite shape of its macroparticles. In reality, it can suffer from artificially high collisionality due to the underresolution of particle number; i.e., the use of a large macroparticle weight. The degree to which particle shape effects compensate for a large macroparticle weight in 1D, 2D, and 3D is presented. The collision time is calculated from PIC simulations based on the decay rate of the velocity autocorrelation function and compared directly with the kinetic theory of Okuda, Birdsall, and Langdon. The theory is found to accurately predict the simulated collision time with varied grid spacings,
plasma conditions, and simulation dimensionalities. The result is a means to predict the timescale of self-consistent Coulomb interactions in the PIC simulation and thus characterize the relevance and implications of numerical thermalization as a function of grid spacing and macroparticle weight. It is determined that reaching the physical thermalization time, let alone approximating the collisionless Vlasov limit, may often be intractable in 3D for macroparticle sizes that resolve the Debye length.
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Astrophysics of Galaxies
Studying HI and the Cosmic Web in the Era of SKA
Hengxing Pan, Martin Meyer, Madalina N. Tudorache et al. (+5 more)
Neutral atomic hydrogen plays a central role in the
evolution of
galaxies. Yet our understanding of how gas is accreted onto
galactic disks, and the way this is governed by the cascade of processes extending up to
cosmic web scales, remains poorly understood. The Square Kilometre Array has the potential to significantly advance our understanding in this field, being able to both resolve
galactic disks with high column density sensitivity, while also being able to survey the large volumes needed to understand the impact of processes at the level of the
cosmic web. In this chapter, we examine recent observational and theoretical progress made in this area, the potential contribution of the SKA, and needed
alignment with other
radio and multiwavelength facilities to advance the field.
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All authors Hengxing Pan, Martin Meyer, Madalina N. Tudorache, S. Lyla Jung, Maryam Arabsalmani, Gabriella De Lucia, Kristine Spekkens, Matt J. Jarvis
Solar and Stellar Astrophysics
Unveiling the nature of barium stars. I. Asteroseismic masses and the evolutionary link between Ba dwarfs and giants
Lupamudra Sarmah, Yerra Bharat Kumar, Simon W. Campbell et al. (+2 more)
Barium
star systems are excellent sites for studying AGB nucleosynthesis, binary
evolution, and mass transfer processes. However, an accurate estimation of their fundamental
stellar parameters is still lacking. Using TESS data, we made the first extensive asteroseismic mass measurements of 31 Ba
giants and 13 Ba
dwarfs. For some, we were able to measure $\Delta P$, ascertaining their evolutionary phase. We then constructed a grid of
stellar models across the relevant mass range, where we accreted AGB material using composition from existing yields. We found that the average masses of the Ba
dwarfs and Ba
giants are significantly different ($1.29\pm0.09~\rm{M}_\odot$ versus $1.96\pm0.16~\rm{M}_\odot$, respectively). However, their mass distributions peak around $1.3~\rm{M}_\odot$. While our sample of Ba
giants spans the low- and intermediate-mass regime, we found no intermediate-mass Ba
dwarfs. The abundance trends of $s$-process elements show an overall anti-correlation with
stellar mass, particularly in the low-mass regime. The
stellar models adopting Monash AGB yields can satisfactorily reproduce the observed light elements, $s$, and heavy-$s$ abundance trends, with an accreted mass of $0.1-0.5~\rm{M}_\odot$, but fail to explain the [hs/ls] ratio. Our results support an evolutionary scenario in which Ba
giants evolve from Ba
dwarfs, with mass
accretion occurring while the progenitor Ba
star is still on the main sequence. In this scenario, a substantial number of intermediate-mass Ba
dwarfs are expected. We found that post-
accretion additional mixing in our models is critical to explain the observed $s$-process abundances in Ba
dwarfs and the low C isotopic ratio ($<30$) in Ba
giants. The mismatch between the model and the observed [hs/ls] ratio suggests that the chemical enrichment of Ba
stars cannot be explained by standard single-
star AGB yields alone (abridged for arXiv).
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All authors Lupamudra Sarmah, Yerra Bharat Kumar, Simon W. Campbell, Sunayana Maben, Bacham E. Reddy
High Energy Astrophysical Phenomena
Accreting Compact Object Binaries with the SKA
Aru Beri, Francesco Carotenuto, Rob P. Fender et al. (+4 more)
Accreting binary systems provide a time-resolved view of the
accretion and ejection processes that are seen in all classes of compact objects, from
stellar-mass to supermassive. They allow us to study the launching of relativistic jets on human timescales, probing how the jets are coupled to the underlying
accretion flow, and providing unique insights that can be extended to supermassive black holes via the well-established mass scale invariance. Comparative studies of jets from different classes of compact objects allow us to determine the impact of mass,
spin,
magnetic fields, and
stellar surfaces on the launching of jets. The jets from black hole X-ray binaries provide probes of the
Galactic black hole population, and an important source of feedback to the surrounding interstellar medium. While existing
radio facilities (including the SKA precursors) have made great progress in this field in recent years, the SKA will enhance such studies via its high point source and surface brightness sensitivity, high angular resolution, and broad frequency coverage. This will enable the extension of our existing black hole studies to the fainter accreting
neutron star and white
dwarf population, the detection of previously-undiscovered systems in a low-luminosity quiescent state, and the extension of our studies to nearby
galaxies, revealing rare, high-
accretion rate systems that probe a key phase of black hole growth.
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All authors Aru Beri, Francesco Carotenuto, Rob P. Fender, James C.A. Miller-Jones, Sara Motta, Valeriu Tudose, Jakob van den Eijnden
High Energy Physics (Phenomenology)
Disentangling Dark Gauge Symmetries with Deep Learning on the Lund Jet Plane
Jinmian Li, Junle Pei and Rao Zhang
While dark sectors with new confining gauge
symmetries are compelling candidates for resolving the dark matter mystery, discerning the underlying dark gauge group structure remains a significant phenomenological challenge. In this work, we systematically investigate the distinct radiation patterns of dark
quarks and
gluons by developing a novel Monte Carlo parton shower simulation framework applicable to arbitrary gauge groups. To handle generalized color
topologies and the momentum
recoil scheme, our
algorithm constructs color dipoles using a group-theoretic tagging procedure. Furthermore, our simulation framework employs an exact three-body phase-space parameterization by analytically solving the cubic kinematic equation for each branching. This enables capturing full mass effects for both dark
quarks and dark
gluons, naturally yielding precise boundaries including mass-induced gaps and dead-cone thresholds. To decode these complex emission
topologies, we utilize the Lund Jet Plane representation alongside a dedicated Neural Sorter Mamba Network. We demonstrate that our framework can successfully disentangle the perturbative footprints of different gauge
symmetries. Finally, we show that our discrimination power remains robust against the unknown non-perturbative details of dark hadronization by maintaining high classification efficiencies even under stringent infrared $k_T$ cutoffs, and we explicitly quantify the impact of massive dark gauge
bosons on the classification sensitivity.
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Earth and Planetary Astrophysics
Physical Characteristics of the Asteroid (469219) Kamo'oalewa as a target of the Chinese Tianwen-2 mission
Xiaobin Wang, Karri Muinonen, Shenghong Gu et al. (+3 more)
The Near-earth asteroid (469219) Kamo'oalewa, a quasi-satellite of the Earth, is going to be observed in site and sampled by the Chinese space mission Tianwen-2 in near future. Here. we analyze its photometric and spectroscopic data to figure out its basic physical properties, which are very important for the sample return task of the Tianwen-2 mission. With photometry inversion methods, we derived a pole $(276^{o}.79, -21^{o}.43)$ with a
spin period of 28.4517 minutes and a slightly flat convex shape. The estimated photometry slope of $0.998 mag/rad$ implies a large albedo of the Kamo'oalewa, i.e. S-type. Using the estimated absolute magnitude of $24.98$ mag, its size could be 27.4m assuming a typical albedo of S-type asteroids. The taxonomy analysis with a constructed ANN tool also supports that the Kamo'oalewa should belong to S-type asreroids, it may be a strong weathering fragment of an A-type or Q-type asteroid. Using derived pole, size and shape information of the target, we estimated its thermal inertia as $163.0 Jm^{-2}K^{-1}s^{-1/2}$ based on the new derived Yarkovski draft $A_2=-13.29349563\times10^{-14}au/day^2$, which means the target has a surface of mixture of grains and small bounds, like the surface of asteroid Bennu.
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All authors Xiaobin Wang, Karri Muinonen, Shenghong Gu, Xin Liu, Xiyun Hou, Jing Huang
Quantum Physics
Preparing two-mode magnonic Schrödinger cat states in a cavity-magnon-qubit system
Gen Li, Gang Liu, Rong-Can Yang et al. (+1 more)
The cavity-
magnon-
qubit system has recently been demonstrated as a new platform for preparing macroscopic
quantum states in magnonic systems. Here, we propose to prepare a two-mode magnonic cat state, which is also a non-Gaussian entangled state, based on this practical system involving two yttrium-iron-garnet (YIG) spheres and a superconducting
qubit coupled to a common microwave cavity. By adiabatically eliminating the cavity and resonantly driving the
qubit, an effective
magnon-
qubit conditional-displacement interaction is achieved. Further working in the
magnon-
magnon strong-coupling regime and considering two identical
magnon frequencies and coupling strengths to the cavity, two hybridized
magnon modes are formed, of which the bright mode is prepared in a cat state after a projective measurement on the
qubit, while the dark mode remains in its initial
vacuum state. Such a state corresponds to a two-mode cat state of two original
magnon modes, which share strong non-Gaussian
entanglement. We also discuss practical dissipation and dephasing effects on the cat state. The results indicate that strong nonclassicality and non-Gaussian
entanglement are present in the two-mode cat state using fully feasible parameters.
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All authors Gen Li, Gang Liu, Rong-Can Yang, Jie Li
Quantum Physics
Quantum metrology of electric and magnetic dipole moments: ultimate limits and optimal regimes
Simone Cavazzoni, Paolo Bordone and Matteo G.A. Paris
The characterization of electric and
magnetic dipole moments (EDM and MDM) in
quantum systems is central to fundamental physics and
quantum sensing. While EDM searches provide powerful probes of CP violation within and beyond the Standard Model, precise MDM estimation is crucial for high-precision magnetometry and the development of
quantum sensors. In this work, we address the ultimate precision limits for separate and simultaneous estimation of both dipole moments in a generic two-level system coupled to electromagnetic fields. We analyze three classes of
quantum probes/strategies:
unitary and depolarizing dynamics, and thermal
equilibrium states. For each, we derive the
quantum Fisher information (
matrix), identify optimal probes, and determine the ideal operating conditions, such as
evolution times and temperatures, that maximize estimation precision. We further assess the compatibility and sloppiness of the statistical models, showing that orthogonal dipole moments configurations enable joint estimation of EDM and MDM, whereas parallel configurations are intrinsically sloppy, permitting only the estimation of a single parameter combination. Our results provide a unified metrological framework for estimation schemes ranging from
neutron EDM searches to molecular magnetometry, and highlight the distinct roles of coherence, noise, and thermalization in multiparameter
quantum sensing of dipole moments.
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Statistical Mechanics
Dynamic dissipative structures in bistable magnetic ordered spin crossover systems: self-oscillations of magnetization
Yu.S. Orlov, N.N. Paklin, S.V. Nikolaev et al. (+2 more)
Dissipative systems can exhibit a variety of behavioral modes, ranging from complex deterministic chaos to the spontaneous emergence of ordered structures. A simple example of the latter is Benard
cells. More complex examples include
lasers, droplet clusters, the Belousov–Zhabotinsky reaction, and biological life. Of particular interest in the context of the formation of spatiotemporal dissipative structures are bistable systems with
spin crossover. This paper discusses the possibility of observing self-oscillations of magnetization in magnetically ordered systems with
spin crossover. The results of theoretical calculations of the nonlinear dynamics of bistable
magnetic systems under nonequilibrium conditions are presented.
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All authors Yu.S. Orlov, N.N. Paklin, S.V. Nikolaev, E.I. Shneyder, V.A. Dudnikov
Mathematical Physics · Cross-listed from math.MG
The Angular Seed Power Map: A Constructive Approach to Recursive Scaling Spirals
Arjen Toni Dijksman
We present the ”Power Spiral Map”, a continuous angular
evolution of the linear coordinate grid established in our previous work. While that previous Power Map utilized a seed value translating along a horizontal axis, this work builds upon a seed angle ($\theta$) projected onto a unit diameter circle. This operation controls two coupled
geometric behaviors: an internal area-preserving partition of unity within a reference square (cos 2 $\theta$ + sin 2 $\theta$ = 1) and an external recursive scaling mechanism (sec $\theta$ and cos $\theta$) that dictates the expansion or contraction of successive generations of squares unfolding as a spiral in the 2D plane. We demonstrate that continuous variation of this angular parameter generates discrete
geometric alignments that yield
polynomial identities, with examples of the Golden Ratio ($\Phi$) and the Plastic Ratio ($\psi$) defined through purely planar intersections.
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