Optics
Seidr update: photonic 'black magic' for high-contrast interferometry using kernel-nulling and photonic lanterns
Nathan K Long, Daniel S Dahl, Christopher H Betters et al. (+13 more)
Seidr is a new interferometric beam combiner within the Asgard Suite, utilizing infrastructure common to the BIFROST instrument at the Very Large
Telescope Interferometer. Seidr combines hybrid mode-selective photonic lantern injection modules with a kernel-nulling photonic chip backend to enable deep H-band nulling for high-contrast studies of
exoplanets, exomoons, and circumstellar
dust. This instrument update summarizes Seidr's current design maturity and recent simulations of the point source - to - lantern outputs. We also outline progress on our neural network-based wavefront estimation scheme, which uses the photonic lantern outputs to sense phase fluctuations, designed to feed back to Baldr's deformable mirror, and improve nuller light injection.
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All authors Nathan K Long, Daniel S Dahl, Christopher H Betters, Julia J Bryant, Nick Cvetojevic, Michael J Ireland, Stefan Kraus, Sergio Leon-Saval, Frantz Martinache, Marc-Antoine Martinod, Barnaby Norris, Jyotirmay Paul, Akira Rodziewicz-Ryan, Adam K Taras, Jin Wei, Peter G Tuthill
Quantum Physics
Complexity of Normalized Persistence Problems for Topological Data Analysis and Local Hamiltonians
Dominic Lowe, M.S. Kim, Roberto Bondesan et al. (+1 more)
Topological data analysis (TDA) is a machine learning technique that uses
topology to extract patterns from data and has shown the potential to exhibit
quantum advantage. A key concept in TDA is persistent homology, which measures the robustness of topological information at different lengthscales. In this paper, we introduce and study the problem of normalized persistence, a practically motivated and easily interpretable version of persistent homology that counts the fraction of holes that persist at different lengthscales. We prove that a variant of normalized persistence is $\mathsf{DQC}_1$-hard and contained in $\mathsf{BQP}$, giving evidence of an exponential
quantum speedup for TDA under the standard assumption that $\mathsf{DQC}_1 \not\subseteq \mathsf{BPP}$. These are the first $\mathsf{DQC}_1$-hardness results for clique complexes, making them directly applicable to TDA instances. We also find a close connection between normalized persistence and the complexity of estimating spectral quantities in the low-energy subspace of local
Hamiltonians. We study a family of such problems, including a low-energy normalized subtrace and spectral density. We show that these are $\mathsf{DQC}_1$-hard for $O(1)$-local
Hamiltonians, strengthening previous results that required log-local interactions. We also introduce a variant of $\mathsf{DQC}_1$ with perfect completeness ($\mathsf{SDQC}_1$) to characterize the hardness of problems normalized by an exact kernel. This includes normalized persistence for $O(1)$-local
Hamiltonians, which we show is $\mathsf{SDQC}_1$-hard.
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All authors Dominic Lowe, M.S. Kim, Roberto Bondesan, Ryu Hayakawa
Earth and Planetary Astrophysics
Refined rotational state and shape model of (98943) Torifune ahead of the Hayabusa2# flyby
P. Fatka, P. Pravec, P. Scheirich et al. (+4 more)
The Hayabusa2# mission will perform a high-speed flyby of near-Earth asteroid (98943) Torifune on 5 July 2026, offering a rare opportunity to compare a pre-encounter
spin and shape model derived from convex light-curve inversion with spacecraft imaging. We refined Torifune's rotational state and shape model using previously published dense light curves, new photometry data obtained in late 2025, and selected sparse photometry data from the Asteroid Terrestrial-impact Last Alert System (ATLAS). A key methodological contribution is a per-measurement weighting scheme that accounts for heterogeneous data quality and cadence through light-curve scatter, rotational-phase-dependent brightness, and correlation-time downweighting of closely spaced measurements. We also estimated uncertainties with an apparition-constrained block bootstrap, resampling complete light curves while preserving the dense/sparse composition of the
dataset and retaining coverage of each apparition. This procedure provides realistic uncertainties for the determined sidereal period, pole direction, and shape parameters. We refine the sidereal period to P_sid = 5.0215221^{+0.0000011}_{-0.0000007} h and confirm a prograde
spin state with the axis near the north ecliptic pole. The nominal pole solution is (\lambda, \beta) = (314\degree, +84\degree), with a 5.4\degree angular uncertainty. The dynamically equivalent ellipsoid has a/b = 1.66^{+0.03}_{-0.07}, whereas its polar axis remains less well constrained, with b/c = 1.49^{+0.44}_{-0.29}. All quoted uncertainties correspond to the two-sided 95% intervals of the block-bootstrap distributions. The forthcoming Hayabusa2# flyby should enable direct evaluation of which elements of this pre-encounter convex inversion model are robust, particularly the pole orientation and global silhouette, and may help constrain the remaining uncertainty in the polar dimension of the body.
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All authors P. Fatka, P. Pravec, P. Scheirich, P. Kušnirák, K. Hornoch, H. Kučáková, M. Hirabayashi
Quantum Physics
Comparing and learning figures of merit for quantum circuit compilation
Harshdeep Singh, Marvin Richter, Mats Granath et al. (+1 more)
To make
quantum algorithms executable on a particular
quantum device, they need to be compiled into
circuits that respect constraints of the
quantum hardware. This compilation usually involves multiple steps, where many hardware-compatible
circuits are generated, and the best
circuit is selected. To say which
circuit is best, the quality of a
circuit is generally quantified by a $\textit{figure of merit}$ (FoM). For FoMs, there is a trade-off between ease of calculation and accuracy in predicted execution quality. Commonly used FoMs, e.g., the number of gates,
circuit depth, etc., are easy to evaluate, but do not directly capture the effects of
circuit structure and noise. On the other end of the spectrum are FoMs that require full
circuit execution and take a prohibitively long time to evaluate. One example is the probability of successful trials (PST), i.e., the probability of obtaining the initial state after running the
quantum circuit followed by its inverse. Here, we investigate advantages and disadvantages of different FoMs, and formulate the properties of an ideal FoM. Based on our results, we propose wPST, a weighted version of the PST that accounts for individual
qubits, not just the whole state. To quickly predict PST and wPST, we design machine learning models that take into account both the
quantum circuit and
quantum hardware data. In numerical simulations and experiments on
quantum processors, we find that our machine learning-predicted FoMs outperform commonly used FoMs, increasing the correlation with the true PST or wPST by over 50%. To make our model useful for
quantum compilers, we devise a two-step process to predict the wPST for non-transpiled
quantum circuits: first, we predict the additional
quantum gates required for the given
quantum circuit, and then we predict the wPST, accounting for coherence times in the
quantum device.
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All authors Harshdeep Singh, Marvin Richter, Mats Granath, Anton Frisk Kockum
Quantum Physics
False vacuum decay in long-range interacting quantum systems
Valerio Pagni, Laura Batini and Nicolò Defenu
We formulate false-
vacuum decay in a mixed-field Ising chain with $1/r^\alpha$ interactions as a spatially nonlocal Euclidean $\phi^4$ theory featuring a fractional spatial kinetic term $\sim |q|^\sigma$, where $\sigma=\alpha-1$. The nonlocal bounce is anisotropic in space-time and develops algebraic spatial tails, challenging the standard thin-wall picture of a compact droplet. Combining thin-wall arguments with numerical solutions of the full nonlocal saddle, we show that these tails preserve the leading thin-wall exponents, manifesting instead in subleading corrections. For $0<\sigma<1$, the lifetime exponent scales with the energy bias $h$ of the metastable state as $B\sim h^{-1/\sigma}$; for $1<\sigma<2$, the leading Coleman scaling $B\sim h^{-1}$ is recovered, while long-range effects are retained in the subdominant term $\sim h^{\sigma-2}$. Our results show that tunable long-range interactions fundamentally reshape bubble nucleation and alter false-
vacuum decay in
quantum simulators.
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Mathematical Physics · Cross-listed from math.SP
Higher order Weyl coefficients for the operator curl
Giovanni Bracchi, Matteo Capoferri and Dmitri Vassiliev
We establish refined spectral asymptotics for the operator curl acting on a connected oriented closed Riemannian 3-
manifold. We treat positive and negative
eigenvalues separately and obtain explicit formulae for the first six global Weyl coefficients. With local Weyl coefficients we compute the first four coefficients as well as the sixth one, and we determine the fifth up to a universal constant. As a consequence, we prove that the eta function of curl (both in its local and global versions) is holomorphic in the complex half-plane $\operatorname{Re}s>-2$. Finally, under appropriate assumptions on the geodesic flow, we improve Bär's asymptotic formulae for the positive and negative counting functions, refining the remainder to $o(\lambda^2)$.
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General Relativity and Quantum Cosmology
Dark energy genesis: modeling dissipative effects in primordial cosmology
Pietro Pellecchia, Alejandro Perez and Salvatore Ribisi
In various approaches to
quantum gravity, spacetime geometry is understood to emerge from more fundamental discrete structures at the Planck scale. As sometimes posited, their presence could lead to dissipative effects in the smooth effective sector. In this paper, we develop the idea of non-conservation in
gravity, by introducing an effective cosmological model within unimodular
gravity, in which a varying cosmological constant arises as a consequence of dissipation. We show that this requires to incorporate hidden degrees of freedom – termed
quantum gravity defects – that act as an effective bath for the matter fields. To illustrate the viability of the framework, we study the case of an Ohmic bath inspired by the Caldeira-Leggett model for Brownian motion, leading to a
diffusion equation for the matter energy density. The results show that, starting from a
primordial universe with no dark energy, dissipation can account for the generation of a small positive cosmological constant.
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Astrophysics of Galaxies
Advancing extragalactic spectral line studies with the Square Kilometre Array Observatory
Jacco Th. van Loon, Viviana Casasola, Manuela Bischetti et al. (+6 more)
We present an overview of the Square Kilometre Array Observatory (SKAO) science potential in the area of extragalactic spectral lines besides 21-cm neutral hydrogen. It highlights the main points from the SKAO Science Book chapters on individual topics, but is augmented by additional prospects. The SKAO will push studies and use of masers, kilomasers, megamasers, molecular and
radio-recombination-line emission and absorption to a wider variety of environments, including to very high
redshift where it may detect the first molecule (HeH$^+$). It will open the door to measurements of hydrogen and helium isotopes, probing the conditions for
star formation and Big Bang nucleosynthesis. While the planned SKAO of the 2030s (AA*) is destined to forge major progress, an SKAO as initially envisaged (AA4) will truly transform the landscape, and an extension towards higher frequencies (up to 24 GHz) would enable water maser and ammonia surveys in nearby
galaxies and systematic molecular gas inventories at
redshift 5.
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All authors Jacco Th. van Loon, Viviana Casasola, Manuela Bischetti, Sandra Etoka, Hans-Rainer Klöckner, Mamta Pandey-Pommier, Mark Sargent, Nick Seymour, Andrea Tarchi
Materials Science
Enhanced hydrogen response of copper-doped TiO$_2$ synthesised by helium-assisted magnetron sputtering
Akash Kumar, Nirmal Kumar, David Kolenatý et al. (+4 more)
Cu-doped TiO$_2$ thin films for hydrogen sensing were synthesised by reactive DC magnetron sputtering in Ar/O$_2$/He mixtures, with the He fraction used as a control parameter for film growth. By combining normal-angle deposition (NAD) and glancing-angle deposition (GLAD) with post-deposition annealing, the effects of He on microstructure formation and sensor performance were examined. X-ray diffraction and electron microscopy revealed that He promotes nanostructuring,
lattice expansion in as-deposited NAD films, increased porosity after annealing, and a stronger anatase character in the final
oxide layers. These structural changes, which enhance the reactive surface area, lead to improved hydrogen sensing at 300\,$^\circ$C in 1~vol.\,% H$_2$. The response of NAD films increased from 1.4 to 6.0 simply by replacing part of the argon with helium, whereas GLAD films showed only a modest increase. The observed nanostructuring is discussed in terms of a simulation-supported growth scenario involving energetic backscattered He, a reduced hammering effect, and cooling-related suppression of adatom mobility, which together favour the formation of a more open sensing layer. Helium-assisted sputtering represents a useful physical route for tailoring
oxide thin films for gas-sensing applications.
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All authors Akash Kumar, Nirmal Kumar, David Kolenatý, Mina Farahani, Jiří Rezek, Tomáš Kozák, Stanislav Haviar
Mesoscale and Nanoscale Physics
One-dimensional carbon nanostructures with periodic graphitic nitrogen substitution
Nicolò Bassi, Shantanu Mishra, Zheng Zhang et al. (+8 more)
Heteroatom substitution is a powerful route to tune the chemical and electronic properties of carbon nanomaterials. In particular, replacement of an sp2 hybridized carbon atom in the
graphene lattice with a nitrogen atom (denoted as graphitic nitrogen) induces substantial changes in the electronic properties. These include changes in the band structure that can influence electronic transport, and magnetism. A key requirement for applications is both the periodic and precise incorporation of the heteroatoms in extended carbon
lattices. Here, we report the on-surface synthesis and characterization of two one dimensional carbon nanostructures, a
polymer and a
graphene nanoribbon, consisting of periodically incorporated graphitic nitrogen atoms. The on-surface reactions toward formation of the nanostructures were monitored by scanning tunneling microscopy. The bond-resolved chemical structures of the reaction intermediates and products were investigated by atomic force microscopy, which enabled atomic-scale visualization of the graphitic nitrogen sites. The electronic properties of the nanostructures were studied by scanning tunneling spectroscopy and density functional theory calculations. Our analyses revealed the presence of localized nitrogen-centered electronic states. In the gas phase where the nanostructures are in a neutral charge state, these states undergo
spin polarization leading to an open-shell ground state. Upon adsorption on Au(111), the nanostructures exhibit electron transfer to the surface, which resulted in a closed-shell ground state. Our results demonstrate a straightforward and generally applicable route to synthesize graphitic nitrogen-substituted carbon nanomaterials with potential applications in spintronics, catalysis and energy storage.
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All authors Nicolò Bassi, Shantanu Mishra, Zheng Zhang, Xiao-Ye Wang, Feifei Xiang, Nils Krane, Carlo A. Pignedoli, Klaus Müllen, Pascal Ruffieux, Akimitsu Narita, Roman Fasel
Instrumentation and Methods for Astrophysics
FINER: development of the wideband millimeter-wave receiver system and preparations for first light on the Large Millimeter Telescope
Akio Taniguchi, Yoichi Tamura, Takeshi Sakai et al. (+38 more)
The recent discovery of an excess of luminous
galaxies in the early Universe necessitates sensitive and wideband millimeter spectroscopy to understand their rapid growth. To address this, we present the development of the Far-Infrared Nebular Emission Receiver (FINER) for the Large Millimeter
Telescope (LMT). The FINER frontend comprises two receivers covering 120-350 GHz (corresponding to ALMA Bands 4+5 and 6+7). The warm optics are designed to enable simultaneous two-band observations. Combined with the 10.24-GHz-wide digital spectrometer array, the system aims to deliver an instantaneous bandwidth approximately five times wider than current ALMA capabilities. We report that the 210-350 GHz receiver has already achieved commissioning-level performance, with sideband rejection further enhanced by the digital sideband separation technique. With installation expected in 2026, we discuss parallel preparations, including integrated testing and commissioning plans for first-look targets.
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All authors Akio Taniguchi, Yoichi Tamura, Takeshi Sakai, Masato Hagimoto, Takuya Hashimoto, Akio K. Inoue, Shun Ishii, Haoran Kang, Masato Kato, Ryohei Kawabe, Kotaro Kohno, Takafumi Kojima, Kianhong Lee, Sho Masui, Akinobu Miyake, Taku Nakajima, Tai Oshima, Wenlei Shan, Tatsuya Takekoshi, Kunihiko Tanaka, Kotomi Taniguchi, Kaoru Tsuji, Issei Watanabe, Tom J. L. C. Bakx, Yoshinobu Fudamoto, Kazuyuki Fujita, Yuichi Harikane, Bunyo Hatsukade, David H. Hughes, Takahiro Iino, Yuki Kimura, Hiroyuki Maezawa, Yuichi Matsuda, Ken Mawatari, Shunichi Nakatsubo, Hideo Sagawa, Peter F. Schloerb, Shigeru Takahashi, Akiyoshi Tsujita, Hideki Umehata, Min S. Yun
Atmospheric and Oceanic Physics
A Wigner-based volumetric transport framework for paraxial waves in random media
Arnaud Coatanhay, Thomas Bonnafont and Angélique Dremeau
We develop a Wigner-based phase-space framework for mean paraxial wave propagation in random media. Starting from the random
parabolic wave equation, we derive the exact
evolution of the realization-dependent Wigner distribution and identify the ensemble-averaged Wigner function as the natural second-order state variable. The averaged equation contains a closure defect, given by a mixed field–medium correlation, which prevents a closed transport equation from being obtained without additional assumptions. We therefore organize the modelling as a hierarchy from the random wave equation to an exact Wigner formulation, then to a nonlocal kinetic closure, and finally to a local Fokker–Planck reduction in the small-angle regime. For the minimal homogeneous isotropic Fokker–Planck model, we derive closed
evolution laws for the quadratic moments, exhibit the cubic-in-distance contribution to beam spreading, and obtain explicit Gaussian and Gauss–Schell propagation formulas. These analytical results are used to validate a phase-space splitting solver in one-dimensional transverse
benchmarks. Comparisons with nonlocal kinetic models show that the diffusive approximation is accurate for narrow momentum-transfer kernels and loses validity in a controlled way as finite-jump effects become significant. Finally, we introduce a first atmospheric specialization based on a regularized
turbulence spectrum, yielding an effective
diffusion coefficient expressed in terms of standard atmospheric parameters.
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Cosmology and Nongalactic Astrophysics
Cosmology with HI Intensity Mapping
Laura Wolz, Gabriele Autieri, José Luis Bernal et al. (+18 more)
The redshifted spectral emission from neutral hydrogen (HI) at rest wavelength 21 cm can be used as a tracer of large-scale structure and its
evolution. Within the HI intensity mapping method, sufficient signal-to-noise is achieved by integrating the line emission within large voxels over a wide sky area and line of sight depth which allows access to the largest scales of the matter distribution. The resulting tomographic maps usually feature low angular and high
redshift resolution. The SKAO will be able to conduct HI intensity mapping experiments observing up to 20,000 square degrees over a wide range of
redshifts. For SKA-Mid, we will employ the array in a fast-scanning single-dish mode using Band 1 and 2 to access 0<z<3, mapping an enormous volume with fast survey speed, allowing for the possibility of a commensal survey producing high angular resolution maps via the on-the-fly imaging of the visibilities. For SKA-Low, we will focus on deep observations to detect the HI signal in a frequency band matching 3<z<6. In this chapter, we will give an overview of HI intensity mapping with the SKAO, including an outline of planned surveys, a discussion of observational challenges, and methodology for power spectrum methodology and forecasts. We present predictions on the constraining power on LambdaCDM cosmology from HI intensity mapping data via power spectrum, and other observables such as bi-spectrum and HI stacking. We also demonstrate the synergy power of HI intensity mapping with other cosmological surveys.
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All authors Laura Wolz, Gabriele Autieri, José Luis Bernal, Maria Berti, Philip Bull, Stefano Camera, Isabella P. Carucci, Zhaoting Chen, Steven Cunnington, José Fonseca, Keith Grainge, Jiakang Han, Wenkai Hu, Dionysios Karagiannis, Mario G. Santos, Marta Spinelli, Liantsoa F. Randrianjanahary, Cora Uhlemann, Matteo Viel, Bernhard Vos-Ginés, Jingying Wang
Atomic Physics
Development of a High-Performance Permanent Magnet System for Ion Trapping Experiments
Jifei Wu, Jiawei Wang, Tianhang Zhang et al. (+4 more)
This work presents the design and fabrication of a compact permanent magnet based on an optimized stacked structure of fifteen NdFeB rings. The tunable NS-SN-NS configuration generates a central
magnetic field of 0.8T with a reconstructed uniformity of 99.988% within a 1mm radius spherical volume. The remaining field inhomogeneity is dominated by radial dipole components. Requiring neither cryogenics nor external power, this design provides a high-performance and cost-effective alternative to superconducting magnets for applications in ion-trap development and
Fourier-transform ion cyclotron resonance mass spectrometry.
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All authors Jifei Wu, Jiawei Wang, Tianhang Zhang, Zichen Su, Liangyu Huang, Wei Wu, Bingsheng Tu
Quantum Physics
Generating one-way computations with flow: flow-preserving rewriting that ignores the interpretation
Miriam Backens
The one-way model is a universal model of
quantum computation, driven by successive adaptive single-
qubit measurements on an entangled resource state. Measurements are non-deterministic, yet if the computation satisfies one of several related families of conditions known as 'flows', the computation can be made deterministic overall by modifying later measurements depending on the outcomes of earlier ones. Flow properties also enable efficient translation from one-way computations to
circuits, motivating research into rewriting one-way computations while preserving the existence of flow. Existing approaches to flow-preserving rewriting are used for compilation or optimisation and preserve both the interpretation and the existence of flow. Here, we broaden our perspective to consider flow-preserving rewriting that does not necessarily preserve the interpretation, with applications to creating test instances for software that works with flow, as well as to generating ansätze for
quantum machine learning. We show that a family of just three flow-preserving rewrite rules suffices to generate any diagram with flow from a trivial diagram with the desired number of inputs and outputs. This rule set is nearly the same as the complete set of flow- and interpretation-preserving rewrite rules for one-way computations in which all measurements are Pauli; and just a small subset of the flow- and interpretation-preserving rewrite rules for arbitrary measurements.
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High Energy Physics (Phenomenology)
Probing a 146 GeV cLFV scalar using the LHC and low-energy experiments
Christina Gao, Lingfeng Li and Z.J. Xiong
The CMS Collaboration reported a local excess at $146~\mathrm{GeV}$ in the search for the
lepton-
flavor-violating decay of the
Higgs boson and additional
Higgs bosons in the $e\mu$ final state at $\sqrt{s}= 13~\mathrm{TeV}$. If confirmed, this would constitute a major piece of evidence of charged
lepton flavor violation (cLFV). We investigate the compatibility of the claimed signal with the full suite of existing low-energy cLFV constraints in a bottom-up effective description: a single real scalar of mass $146~\mathrm{GeV}$ coupled to
gluons and to all charged-
lepton bilinears, with seven free parameters that simultaneously control the LHC production cross section, every di-
lepton decay channel, and every low-energy cLFV observable. A
Bayesian MCMC analysis against $\mu-e$ conversion, muonium-antimuonium oscillation, three-
lepton and radiative LFV decays, semileptonic $\tau$ LFV decays, and LHC di-
lepton searches yields a preferred mode with peaked value $Y_{e\mu} \sim 10^{-4.09}$, already cut into by the current $\mu-e$ conversion limits. The projected sensitivities of Mu2e, COMET, Mu3e, MACE, MEG~II, Belle~II, STCF, and the HL-LHC directly probe the region of coupling space selected by the CMS excess, so the complementarity between high-energy and low-energy cLFV probes will either corroborate or decisively exclude the scalar interpretation of the anomaly within the next decade.
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Instrumentation and Detectors
Secondary electron yield from aluminium-coated foils for muon tagging and beam monitoring up to 60 MeV/c
Gianluca Janka, Michael W. Heiss, Maxime Lamotte et al. (+2 more)
The feasibility of foil-based
muon tagging is investigated in the momentum range below 60 MeV/c, with particular focus on its applicability to the low-momentum range spanning approximately 2.5 MeV/c to 20 MeV/c, where no efficient and minimally invasive detection scheme is currently established for continuous beams. Secondary electron emission from a 7 um Mylar foil coated with 50 nm aluminium is investigated using a continuous negative
muon beam with nominal momenta between 12 MeV/c and 60 MeV/c at the piE1 beamline at PSI. The emitted electrons are detected with position-sensitive microchannel plate detectors, enabling particle tagging and spatial characterization of the beam. The detection efficiency and corresponding secondary electron yield are extracted and benchmarked against literature data for
protons, showing good agreement and confirming reliable
muon tagging. The observed trend for negative
muons is consistent with the well-established increase in ion-induced secondary electron emission toward lower particle velocities, suggesting improved performance in the low-momentum regime. A proof-of-principle reconstruction of the
muon beam profile is demonstrated by correlating detected electron positions with their emission point at the foil. These results establish foil-based tagging as a viable approach for combined timing and minimally invasive beam monitoring, bridging the gap between high- and low-energy
muon instrumentation.
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All authors Gianluca Janka, Michael W. Heiss, Maxime Lamotte, Xiao Zhao, Thomas Prokscha
High Energy Physics (Experiment)
Searching for Dark Photons with a room-temperature dielectric haloscope
Siyin Li, Paschos Ioannis, Zhengyin Yang et al. (+4 more)
We present a search for dark-
photon dark matter with a room-temperature dielectric multilayer haloscope. The dielectric stack enhances
photon conversion near 2 eV, and a spatially resolved CMOS focal plane records the emitted
photons with few-
photon sensitivity. We calibrate the stack-lens-CMOS response in situ and use the calibrated focal-plane pattern in a template-based inference. With 904 h of search data and 404 h of background-control data, we observe no excess and set a 90% confidence-level upper limit of $\kappa < 4.0\times10^{-13}$ for dark-
photon dark matter with mass 1.9$\,\mathrm{eV}/c^2$.
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All authors Siyin Li, Paschos Ioannis, Zhengyin Yang, Alexandros Spiliotis, Husheng Guan, Pavlos G. Savvidis, Shengchao Li
Quantum Physics
A Galton-Watson estimate for Dyson series
Hans Maassen and Dmitri Botvich
We consider the question of convergence of particular series of integrals, which are labeled by rooted trees. Necessary and sufficient criteria for convergence are obtained, together with an explicit expression for the sum. The technique used is strongly reminiscent of the generating function approach of Galton and Watson to branching processes. The interest in these series derives from the Dyson series expansion for the perturbation of a free
quantum dynamics by a local potential: the convergence of the series imlies that the perturbed dynamics exists and is unitarily equivalent with the free one.
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General Relativity and Quantum Cosmology
Odd-parity ringdown gravitational waves of a spherically symmetric black hole with perfect fluid accretion
Rikuto Ohashi, Yasutaka Koga, Hiroyuki Nakano et al. (+2 more)
The ringdown waves from a black hole offer a clean probe of strong-field
gravity, but a matter distribution that may be present around a realistic black hole renders the background spacetime dynamical and the ringdown frequencies time-dependent. We study the odd-parity ringdown of a Schwarzschild black hole that grows through the dilute, steady, spherically symmetric
accretion of a perfect fluid. Working to first order in the
accretion rate, we compute the ringdown waveform directly in the time domain on this dynamical background. Since the odd-parity matter perturbation decouples from the metric perturbation, the wave mode can be described by a purely tensorial mode on the accreting background. In particular, the ratio of the imaginary to the real part of the frequency cancels both the secular variation caused by the growth of the black hole and the
redshift factor, so that its deviation from the Schwarzschild value purely reflects the surrounding environment. The time dependence of the frequency, on the other hand, reflects the
accretion rate and allows us to define a second observable tied to it. We argue that measuring these observables across multiple modes may provide significant information to constrain the surrounding environment of the black hole.
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All authors Rikuto Ohashi, Yasutaka Koga, Hiroyuki Nakano, Kota Ogasawara, Chul-Moon Yoo
Lattice Field Theory
Staggered fermions with taste splitting mass term on dynamical configurations
Gianluca Fuwa, Nuha Georgiev-Chreim and Christian Hoelbling
We present numerical results of staggered
fermions with a taste splitting mass term on dynamical configurations. The rise of gluonic counterterms from rotational
symmetry breaking is studied for a single taste operator and the pion propagator is computed. Preliminary numerical results are given for
lattice sizes up to 16^4.
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Materials Science
NanoBTE: Fast Iterative Solution of the Phonon Boltzmann Transport Equation for Nanoscale Heat Transport
Hongjiang Chen, Hai-Xuan Lin, Xiaole Tian et al. (+7 more)
Nanoscale heat dissipation has become a critical challenge in advanced
semiconductor devices, where
phonon transport can strongly deviate from the classical
Fourier description due to the boundary scattering and ballistic effects. In this work, we propose NanoBTE, a deterministic finite-volume solver for the non-gray
phonon Boltzmann transport equation under the relaxation-time approximation. The solver supports complex two- and three-dimensional geometries, band-resolved
phonon properties, discrete-ordinates angular quadrature, volumetric heat generation, and multiple
phonon boundary conditions, including thermalizing, diffuse, and specular reflections. %To improve the efficiency of multiscale simulations, both sequential and synthetic iterative schemes are implemented, where the latter couples the microscopic
phonon transport equation with a macroscopic
diffusion-type temperature equation to accelerate convergence in near-diffusive regimes. Both sequential and synthetic iterative options are implemented for the steady-state solution. Furthermore, NanoBTE adopts a band-direction task decomposition strategy, enabling efficient MPI-based CPU parallelization and GPU acceleration of the dominant sparse transport operations.
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All authors Hongjiang Chen, Hai-Xuan Lin, Xiaole Tian, Hongyu Chen, Juan Zhang, Shengyao Yan, Hezhu Shao, Yu Wu, Junjie Liu, Hao Zhang
Mathematical Physics · Cross-listed from math.AP
Isotropy and Galilean invariance of Lattice Boltzmann Method: Theoretical and numerical analysis using oblique dipole benchmark *
François Dubois, Souleymane Kadri Harouna, Pierre Lallemand et al. (+1 more)
This work focuses on the two-dimensional, nine-velocity (D2Q9)
lattice Boltzmann model. First, we show that the D2Q9 scheme cannot achieve secondorder accuracy unless the cubic velocity terms are neglected, and we explain how some of these parasitic terms can be eliminated. Second, we demonstrate that the standard choice of the
equilibrium distribution has no effect on the equivalent PDE at second order. Finally, we numerically investigate the effect of these cubic terms and study different choices of
equilibrium distributions using a new
benchmark called the Oblique Dipole
Benchmark, which describes obliquely propagating 2D
vortex dipoles with periodic boundary conditions.
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All authors François Dubois, Souleymane Kadri Harouna, Pierre Lallemand, Mohamed Mahdi Tekitek
Quantum Physics
Quantum Annealing for Dynamic Portfolio Optimization under Realistic Transaction Costs
Escolástico Sánchez-Martínez, Senaida Hernandez Santana, Ventura Sarasa Laborda et al. (+3 more)
This paper investigates and compares
quantum and classical investment strategies for portfolio construction under realistic trading and allocation constraints. The study considers a multi-period portfolio re-balancing setting in which asset weights are subject to lower and upper bounds, class-level exposure restrictions, and turnover limitations. On the
quantum side, the portfolio selection problem is reformulated as a quadratic unconstrained binary optimization (QUBO) model through a finite binary encoding of asset weights, and subsequently embedded into a constrained quadratic model (CQM) solved by a hybrid
quantum-classical optimization workflow. On the classical side,
benchmark allocation strategies are introduced to provide an economically meaningful reference for performance assessment. The proposed framework jointly evaluates portfolio efficiency from two complementary perspectives: business performance, measured through return,
volatility, and a measure of the trade-off between them, the Sharpe ratio; and computational performance, assessed through solver structure, constraint handling, and hardware execution characteristics. The resulting comparison provides a rigorous basis for understanding the practical role of
quantum annealing in constrained portfolio optimization, while clarifying both its modeling advantages and its current implementation limitations relative to established classical approaches.
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All authors Escolástico Sánchez-Martínez, Senaida Hernandez Santana, Ventura Sarasa Laborda, Pablo Serrano Molinero, Guillermo Botella Juan, Alberto del Barrio García
Earth and Planetary Astrophysics · Cross-listed from cs.CE
Uncertainty Quantification Study of a Re-entry Breakup
Tommy Williamson, Beatriz Jilete, Emma Stevenson et al. (+3 more)
The uncertainty associated with breakup events that occur during atmospheric re-entry is severe. Limited attempts to gain a better knowledge of this environment have included the use of breakup recorder-type sensor capsules that are designed to escape the demising debris cloud and survive in order to transmit data. This work models a breakup recorder undergoing this process as a rigid body experiencing hypersonic aerothermodynamic loads alongside collision dynamics with components of the demising container vehicle. The re-entry of the Edoardo Amaldi Automated Transfer Vehicle (ATV3) and the recorder placed on board, the Re-Entry Breakup Recorder 4 (REBR4) is studied in the present work. After a deterministic exploration of the nature of the dynamics of the problem, uncertainty quantification is performed to investigate the effects of initial spacecraft state, REBR detachment conditions and spacecraft fragmentation states. From this data, inferences about the nature of the real re-entry event indicate that detachment of the recorder from the cargo bay prior to main breakup events is more likely than the alternate hypothesis of the container vehicle experiencing high rotation rates.
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All authors Tommy Williamson, Beatriz Jilete, Emma Stevenson, Stijn Lemmens, Massimiliano Vasile, Marco Fossati
Materials Science
Data-driven multi-objective optimization for alloy recycling using factorization machines and quantum annealing
Thomas Plehn, Katrin Bugelnig, Silvana Tumminello et al. (+2 more)
Quantum annealing has the potential to provide practical
quantum advantage for complex optimization tasks. Here, we present a systematic assessment of an integrated factorization-machine and
quantum-annealing workflow (FM+QA) for a technologically relevant application: multi-objective Pareto optimization in metal up-cycling through
alloy design. To address the non-convex nature of the Pareto front, we employ the recently proposed data-driven Tchebycheff scalarization (DDTS) scheme. Our results show that FM+QA extends the applicability of QUBO-based optimization to data-driven materials discovery problems with multiple competing objectives. In particular, we analyze the scaling behavior of the approach and compare
quantum annealing with classical simulated annealing using both regular binary encoding and one-hot encoding. Finally, we provide a critical perspective on the problem sizes and encoding strategies for which
quantum-annealing-based optimization may become practically beneficial in the near future.
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All authors Thomas Plehn, Katrin Bugelnig, Silvana Tumminello, Daniel Barragan-Yani, David Melching
High Energy Physics (Phenomenology)
A Unified Dark Matter Explanation for $\boldsymbol{B^+ \!\to K^+\nu\bar{\nu}}$ and the Super-Kamiokande Antineutrino Excess
Shu-Yu Ho, Jongkuk Kim and Pyungwon Ko
Recent results from Super-Kamiokande and Belle II have revealed intriguing excesses over Standard Model expectations. Super-Kamiokande observes a mild excess of $\bar{\nu}_e^{}$-like events near $20\,\,\mathrm{MeV}$, while Belle II reports a branching fraction for $B^+ \!\to K^+\nu\bar{\nu}$ that exceeds the Standard Model prediction by approximately $2.7\sigma$. In this work, we study the simplest UV-complete complex scalar dark matter model with a gauged $\text{U}(1)_{\textsf{L}_\mu - \textsf{L}_\tau}^{}$
symmetry. We demonstrate that a light dark sector can simultaneously reproduce the observed dark matter relic density and accommodate both excesses within a unified framework.
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Optics
Griffiths Anomalous Absorption in Sparse-Loss Photonic Lattices
Stefano Longhi
Light absorption in photonic
lattices with sparsely distributed loss sites exhibits behavior analogous to Griffiths physics. Under uniform excitation, the transmitted power shows a stretched-exponential decay and a non-monotonic dependence on the loss strength, with an optimal loss rate that maximizes absorption. This behavior arises from rare, long loss-free segments that act as weakly coupled, long-lived photonic channels, rather than from exceptional point physics or interference effects. Using a minimal tight-binding model with binary quenched dissipation, we show that rare regions produce a universal Griffiths-type subexponential decay. Sparse-loss photonic
lattices thus provide an accessible platform to observe disorder-induced anomalous absorption and rare-region Griffiths physics.
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Quantum Physics
Broadband characterization of polarization mode dispersion for quantum communication channels
Vadim Rodimin, Konstantin Kravtsov, Rui Ming Chua et al. (+5 more)
We present a method for characterizing depolarization in fiber channels carrying broadband polarization-encoded optical signals. Wavelength-dependent polarization mode dispersion maps each input polarization to a trajectory on the Poincaré sphere; we show that the singular value decomposition of the band-averaged rotation
matrix yields, in closed form, the optimal input states, the associated mutually unbiased measurement bases, and the resulting projection error probabilities. The three singular values provide a compact, bandwidth-dependent channel signature that distinguishes first- from higher-order dispersion, and yield the bandwidth at which the worst-case error probability reaches 3% as a practical filtering budget. We perform a second-order analysis of the band average that treats the two higher-order mechanisms: variation of the differential group delay at a fixed principal-state axis and wander of that axis with wavelength. We characterize 12 deployed fiber links in Masdar City and demonstrate mitigation by concatenating two channels through a single polarization controller, a step towards nonlocal compensation. The analysis is implemented in an openly available Python library for fiber-channel characterization.
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All authors Vadim Rodimin, Konstantin Kravtsov, Rui Ming Chua, Xingjian Zhang, Aleksei Ponasenko, Yury Kurochkin, Alexander Ling, James A. Grieve
High Energy Physics (Theory)
Singularities, Entropy and the Arrow of Time, or Is CRT a Gauge Symmetry in Quantum Gravity?
T. Banks
We examine the question of whether the discrete transformation CRT is a gauge
symmetry of “
Quantum Gravity". Since the phrase in quotes is not yet completely well defined, we first try to define specific frameworks in which one might ask the question. We find that the general answer is NO. In asymptotically flat and AdS spaces, CRT is an asymptotic gauge
symmetry in the same sense that the continuous parts of the Poincare/AdS isometry groups and scalar internal
symmetries are. In eternal dS space it can be considered a spontaneously broken gauge
symmetry if a certain “Alice String" configuration is allowed in the Thermofield double
Hilbert space. This requires an extension of the conventional Chern-Simons rewriting of $2 + 1$ dimensional
gravity. This interpretation only makes sense if we consider the underlying
quantum mechanics to be time independent. General
quantum measurement and semi-classical gravitational restrictions on measuring devices put a priori limits on the existence of detectors with clocks that can actually measure proper time along a classical dS geodesic.
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