Quantum Physics
Quantum walker trapped by self-similarity of the Sierpiński carpet
Tomasz Sowiński
We study the dynamics of a single
quantum particle on a finite-size square
lattice with a fractal structure resembling the Sierpiński carpet, and compare it to the dynamics on a uniform
lattice of the same size. For a particle initially localized at a corner of the
lattice, we monitor the probability of finding it near the initial and opposite corners using zone-integrated probabilities, allowing a consistent comparison across fractal orders. While on the uniform
lattice the particle reaches the opposite corner ballistically, in a time proportional to the
lattice size, on the Sierpiński
lattice it becomes increasingly confined to the vicinity of its initial position. We show that this trapping builds up self-similarly across the whole hierarchy of corner zones of the
lattice.
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Materials Science
Structural Chirality from Short-Range Order in Heteroanionic Materials
Benjamin J. Morgan
Established routes to structural chirality in inorganic
crystals predominantly depend on
symmetry-lowering atomic displacements of an achiral parent structure. We show that chirality can instead be forced by the short-range order of two anion species over the sites of an achiral parent, independent of atomic displacements. ReO$_3$-type oxyfluorides with a 2:1 anion stoichiometry, such as NbO$_2$F, exhibit two ordering patterns, cis octahedral coordination and period-three anion-chain ordering, both of which are rooted in the off-centring of $d^0$ cations. By direct enumeration, we prove that every arrangement combining both orderings on the smallest commensurate
cell is
chiral, belonging to a Sohncke space group. For NbO$_2$F, density-functional theory (DFT) calculations predict a homochiral $P3_121$ ground state. Wang-Landau Monte Carlo simulations of a DFT-trained cluster-expansion model predict that the
chiral phase remains the
equilibrium state up to a first-order transition at 494 K. We also identify three known vacancy-ordered compounds, BaZnO$_2$, BaCoO$_2$ and $\beta$-Fe$_2$SeO, whose structures each map onto one of the enumerated
chiral arrangements. Together, these results establish short-range order as a route to structural chirality, and mark heteroanionic and vacancy-ordered materials in which both orderings are active as candidates for new
chiral phases.
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Earth and Planetary Astrophysics
Circular polarization as a probe of cloud properties and asymmetries in giant exoplanet atmospheres
M. B. Michaelis and S. Wolf
For
planets in the
Solar System, circular polarization measurements complement linear polarimetry by providing additional information on cloud particle properties. As the disk-integrated circular polarization is 0 for symmetric
planets, observing intrinsic circular polarization of spatially unresolved
exoplanets requires stable spatial asymmetries such as circumplanetary rings. We investigated the potential of circular polarization measurements at optical and near-infrared wavelengths to determine optical properties of cloud particles in the atmospheres of
giant exoplanets and characterize asymmetries. For 20 selected cloud condensates spanning a wide range of refractive indices, we calculated optical properties using Mie scattering theory. The circular polarization of starlight scattered by cloudy
exoplanets was calculated with Monte Carlo radiative transfer simulations. To explain the connection between optical properties and planetary circular polarization, we derived an interpretative model of the first two scattering orders. Planetary hemispheres with atmospheres including cloud particles with a large imaginary part, $k$, of the refractive index show distinct circular polarization phase curves dominated by scattering first by gaseous molecules and then by cloud particles. The intrinsic degree of circular polarization, $P_\mathrm{c}$, is at most $3\cdot 10^{-4}$. When the cloud particles have a low $k$, they instead induce even smaller but more predictable circular polarization dominated by scattering solely by cloud particles. Circular polarization of starlight reflected by
giant exoplanets is sensitive to cloud particle composition and large-scale asymmetries but remains a subtle signal. While promising for characterizing clouds under favorable conditions, practical detection requires technological advances in polarimetry and careful disentanglement from
stellar background signals.
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Computational Physics
From populations to absolute binding affinities in molecular simulations: exact volumetric terms and practical estimators
Davide Mandelli, Emiliano Ippoliti and Charles Plate
Biomolecular simulations of binding commonly confine the unbound ligand with volumetric restraints to accelerate convergence. However, a general account of how such restraints enter the volumetric term of the standard binding free energy, and of how this term should be evaluated from histogram data, is currently lacking. We take as our starting point the established relation, in the dilute limit, between the binding constant $K$ and the relative populations of the bound and unbound states, which we re-derive from the canonical partition function of molecular solutes in explicit solvent. Building on this relation, we show that a restraint that leaves the bound state unaffected and confines a homogeneous unbound region modifies the volumetric term in a single way, by replacing the system volume with the volume of the region over which the unbound population is evaluated. This yields closed-form
estimators for restrained simulations, computable from histograms of any suitably defined reaction coordinate, with the volumetric term kept explicit. Previous expressions based on the potential of mean force are recovered as a special case. The analysis also exposes two distinct errors in current practice: single-bin
estimators, which reduce the bound state to one histogram bin and are not valid
estimators of $K$, and working formulas that omit the bin width entering the volumetric term, which make the result depend on the unit of length. We apply the
estimators to a Lennard-Jones dimer, the cucurbit[7]uril/1-adamantanol host–guest complex, and the galactonate–DgoT ligand–
protein complex.
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Mathematical Physics
Multi-frequency far-field data enrichment for electromagnetic source reconstruction
Atyab Khalifa Al-Shaqsi, Heba Mohammed Al-Subhi, Xianchao Wang et al. (+2 more)
Reconstructing unknown electromagnetic sources from far-field radiation patterns is a fundamental inverse problem with broad applications in biomedical imaging, non-destructive testing, and telecommunications. In practical settings, however, collecting dense multi-frequency far-field measurements at the Nyquist sampling rate is often infeasible. Under-sampled or sparse data introduce non-radiating source components that sever the uniqueness of the solution, creating severe artifacts when standard inversion techniques are applied. To overcome this limitation, we present a two-stage reconstruction strategy exploiting the physical property that compactly supported, geometrically sparse sources exhibit a finite rate of innovations (FRI). In the first stage, we construct an associated wrap-around structured Hankel
matrix. By leveraging the low-rank property of the
matrix due to FRI of the unknown sources, we enrich the sub-sampled data. To that end, we convert missing multi-frequency far-field data recovery into a constrained
matrix completion task solved via Annihilating Filter-based Low-rank Hankel
Matrix Completion Approach (ALOHA). In the second stage, a
Fourier inversion scheme reconstructs the current source density from the enriched
dataset. Extensive numerical evaluations on electromagnetic source models show that our enrichment framework effectively eliminates under-sampling artifacts and resolves non-uniqueness challenges. The method delivers accurate and stable reconstructions under high sub-sampling rates (e.g., with $30$% to $50$% available samples) and strong noise conditions ($10$ dB SNR), outperforming standard $\ell_1$-compressed sensing baselines.
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All authors Atyab Khalifa Al-Shaqsi, Heba Mohammed Al-Subhi, Xianchao Wang, Shujaat Khan, Abdul Wahab
Fluid Dynamics
Laminar gaps mirror turbulent puffs in pipe flow
Shai Kapon, Tobias Grafke and Anna Frishman
Pipe flow at intermediate Reynolds numbers, between the laminar and fully turbulent regimes, takes the form of several spatially and temporally intermittent phases in which turbulent and laminar states coexist. In the lower range, $Re\in (1750,2300)$,
turbulence appears in the form of localized traveling structures called "puffs", which form long-lived chaotic dynamical states, whose
stochastic decays and splits control the steady state intermittency. At the other end, $Re\in (2300,3000)$, puffs are replaced by an extended turbulent state, with laminar pockets intermittently forming and disappearing within it. Using direct numerical simulations of pipe flow at $Re = 2400, 2450, 2500, 2550$, we provide evidence that these laminar gaps form a distinct dynamical state analogous to puffs: a traveling laminar pocket in a turbulent surrounding, stabilized by a shear-dependent self-tuning mechanism. We analyse the mean spatial profile of these gaps and show that their lifetimes are exponentially distributed, suggesting that gap closing corresponds to an escape from a chaotic saddle. Finally, we suggest these laminar gaps become unstable and disappear at a finite Reynolds number, $Re\sim 2900$, which can be interpreted as the onset point of spatially and temporally homogeneous
turbulence.
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Quantum Physics
Quantum States Protection under Environmental Noise
Kai Wang and Zhen-Yang Peng
All realistic
quantum systems are inevitably in contact with the environment. Suppressing theimpact of environmental noise is a critical challenge in cutting-edge
quantum technologies. In thiswork, we introduce and systematically analyze a scheme for the protection of
quantum states againstamplitude-damping (AD) noise based on the
circuit structure called the
quantum filter. Filtrationcircuits employing single- and multi-control
qubits are examined, and their capability to enhance stateprotection fidelity while preserving a high success probability is discussed. Moreover, for many-bodyqubit states, those with a fixed
quantum Hamming weight can be perfectly protected against ADnoise, whereas states with the largest Hamming weight difference set a lower bound on the achievableprotection fidelity. Our work provides a resource-efficient route for
quantum state protection withoutrequiring full
quantum error correction.
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Instrumentation and Methods for Astrophysics
Characterization of the MUSE NFM PSF as a function of atmospheric conditions: TipTop calibration
Enrico Congiu, Fuyan Bian, Carlo F. Manara et al. (+8 more)
The Multi Unit Spectroscopic Explorer (MUSE) achieves exceptional spatial resolution in narrow-field mode (NFM) thanks to the GALACSI adaptive optics (AO) system. However, limitations in point spread function (PSF) characterization still hinder the full exploitation of its capabilities. In particular, the current exposure time calculator (ETC) lacks an accurate PSF model, preventing users from reliably predicting the signal-to-noise ratio of NFM observations during proposal preparation. To address this limitation, we analyzed a large set of archival standard-
star observations to quantify how NFM PSF properties vary with observing conditions, including airmass, seeing, coherence time, wind speed, and wavelength. We then used this reference
dataset to calibrate TipTop, a fast AO PSF simulation tool that will be integrated into the next release of the MUSE NFM ETC. Our results demonstrate that calibration against real on-sky data is essential for accurate PSF modeling. In particular, we find that reproducing realistic PSFs requires both an additional static aberration term and an airmass-dependent tip-tilt jitter component. The calibration performs well at wavelengths longer than 7000 A, while additional corrections are still required at shorter wavelengths, likely due to unmodeled chromatic aberrations. Once implemented in the ETC, this tool will provide condition-dependent NFM PSF predictions and more reliable signal-to-noise estimates.
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All authors Enrico Congiu, Fuyan Bian, Carlo F. Manara, Arseniy Kuznetsov, Guido Agapito, Johanna Hartke, Timo Kravtsov, Lisa-Marie Mazzolo, Fabio Rossi, Cedric Plantet, Fernando Selman
Strongly Correlated Electrons
Ghost-RISB for Correlated Electron-Phonon Systems: Application to the Hubbard-Holstein Model
Samuele Giuli, Ricardo J. Campos-Lopes, Emin Moghadas et al. (+1 more)
We develop a generalization of the ghost-rotationally-invariant slave-
boson (ghost-RISB) method that incorporates local
phonon modes coupled to arbitrary on-site electronic degrees of freedom, enabling a nonperturbative treatment of electron-electron and electron-
phonon interactions within an efficient variational framework. The method extends the ghost-orbital construction to capture dynamical self-energy effects and
phonon-induced renormalizations beyond static slave-
boson approaches. Benchmarking against dynamical mean-field theory (DMFT) results for the Hubbard-Holstein model, we find excellent quantitative agreement for electron quasiparticle weights and
phonon properties across a wide range of coupling strengths, and it captures accurately the competition between electron-electron and electron-
phonon interactions. We show that the inclusion of the ghost orbitals is crucial to accurately describe the regime of low-frequency, strongly dynamical,
phonons. The extended ghost-RISB achieves this accuracy at a fraction of the computational cost of DMFT, due to its self-consistency rooted in static observables instead of dynamical ones, enabling rapid exploration of correlated electron-
phonon phase diagrams. We exploit this advantage to characterize the most demanding regime of strong coupling and adiabatic
phonons. Our analysis shows a suppression of the superconducting order parameter, which is interpreted as a Franck-Condon-like reduction of the overlap between the
phonon wavefunctions associated with empty and doubly-occupied sites in the bipolaronic regime.
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All authors Samuele Giuli, Ricardo J. Campos-Lopes, Emin Moghadas, Massimo Capone
Applied Physics
Memristive Behavior and Mechanism in Solid-State Nanopores
Zhiwei Li, Ngan Hoang Pham, Shi-Li Zhang et al. (+1 more)
Nanofluidic memristors whose conductance evolves through history-dependent ionic transport and dynamic interfacial processes are promising building blocks for ionic neuromorphic applications. However, most existing designs rely on biological nanopores,
polymers, and two-dimensional materials, which limit scalable fabrication and poses challenges to integration of ionic computing
circuits and systems. Here, we report memristive behaviors of silicon-based solid-state nanopores (SSNPs) fabricated based on wafer-scale
semiconductor processes. The SSNPs exhibit hysteretic current-voltage characteristics with a dependence on voltage sweeping frequency, electrolyte concentration, and nanopore geometry. To investigate the physical origin of their
memory feature, the measured current of the SSNPs is decomposed into resistive, capacitive, and memristive components. An ion adsorption-desorption kinetics is developed to explain and predict the memristive behavior. A dynamical system analysis further reveals that the memristive behavior arises from delayed relaxation, thereby linking the measured hysteresis to the observed adaptive ionic response. Together, these findings establish native SSNPs as scalable ionic memristive elements and provide a generalized electrokinetic mechanism for memristive behavior under nanoconfinement. The resulting analytical framework connects device characterization with the underlying dynamics, deepens mechanism understanding, and guides the design of ionic neuromorphic devices.
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All authors Zhiwei Li, Ngan Hoang Pham, Shi-Li Zhang, Chenyu Wen
Materials Science
Growth and characterization of GaN/Ga2O3 Nanowire Heterostructures for Ultraviolet Optoelectronics
Edgars Butanovs, Eriks Dipans, Martins Zubkins et al. (+10 more)
Ultraviolet-range GaN/b-Ga2O3
heterostructures were fabricated and investigated in both planar and nanowire geometries using pulsed
laser deposition and reactive magnetron sputtering from a
liquid gallium target for b-Ga2O3 deposition, while both GaN nanowire arrays and planar p-type Mg-doped GaN layers were grown by metal-organic chemical vapor deposition. Precise control of film uniformity and thickness was achieved as confirmed by structural and morphology studies using X-ray diffraction, X-ray photoelectron spectroscopy, atomic force microscopy and scanning electron microscopy. Planar n-Ga2O3/p-GaN heterojunction diodes were electrically and photoelectronically characterized, exhibiting pronounced rectifying behavior, high forward current and a visible-blind ultraviolet photoresponse under zero external bias, demonstrating intrinsic self-powered operation. Furthermore, GaN/b-Ga2O3 core/shell nanowire
heterostructures were developed and systematically studied with a focus on morphology control and process optimization. The influence of deposition parameters on shell thickness, uniformity, and tapering was investigated, enabling improved conformality of the b-Ga2O3 coating on the M-plane facets of GaN nanowires. The results highlight the viability of physical vapor deposition techniques for forming GaN/b-Ga2O3
heterostructures and establish a pathway toward nanowire-based ultraviolet optoelectronic devices.
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All authors Edgars Butanovs, Eriks Dipans, Martins Zubkins, Edvards Strods, Anatolijs Sarakovskis, Juris Purans, Ashutosh Kumar, Sergiy Khartsev, Martin Berg, Anders Hallen, Qin Wang, Joseph le Pluart, Peter Ramvall
Quantum Physics
Motional refocusing for trap-off Rydberg gates
Yoav Sagi, Ofer Firstenberg, Nir Davidson et al. (+1 more)
Rydberg entangling gates in optical-tweezer arrays are commonly executed with the trapping light switched off, so every gate contains a release–and–recapture cycle that heats the atomic motion and can ultimately limit
circuit depth. We develop a motional refocusing protocol that exactly removes this heating in the harmonic approximation using only programmable intensity switching of the trapping light. The protocol closes the release–and–recapture cycle for every matched harmonic mode, returning arbitrary motional populations and coherences exactly up to ordinary
evolution under the static trap. We derive the recovery sequence in closed form for arbitrary catch depth and prove that, within the experimentally relevant regime, it is the unique globally time-optimal solution under bounded trap intensity. The harmonic theory is then extended in two directions. First, we construct exact common-intensity recovery sequences that simultaneously refocus several nondegenerate harmonic modes, including radial–axial and fully anisotropic three-dimensional traps. Second, we derive a composite sequence that suppresses the leading anharmonic correction of weakly anharmonic traps by canceling all first-order motional transitions induced by the quartic anharmonicity, changing the residual heating law from $U_0^{-2}$ to $U_0^{-4}$. Wave-packet simulations in realistic Gaussian tweezers validate the analytic theory and quantify the residual effects of anharmonicity, finite switching ramps, trap ellipticity, and control errors. Applied to representative cesium Rydberg gates, the protocol suppresses the dominant recapture heating to the anharmonic floor and prevents the associated motional Doppler contribution from increasing with
circuit depth. The resulting framework provides a practical route toward heating-free trap-off neutral-atom gates using only trap-intensity modulation.
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All authors Yoav Sagi, Ofer Firstenberg, Nir Davidson, Guy Raz
Materials Science
An Exchange-Correlation Functional for Fast and Accurate Modeling of Ferroelectric Perovskites
Owain T. Beynon and Chiara Gattinoni
We present a novel exchange correlation functional, C09x-PBEc, which combines C09 exchange with PBE correlation, to accurately model the ferroelectric properties of perovskites while retaining the computational efficiency of GGA functionals. With a growing interest in developing machine learning interatomic potentials (MLIPs) to model large-scale ferroelectric systems of technological relevance, it is important to scrutinise the density functional theory exchange-correlation functionals which are used to compute the forces, energies and stresses the MLIP is trained on. Using the example of the prototypical ferroelectrics lead titanate, PbTiO3, and barium titanate, BaTiO3 we show that many widely used functionals tend to overestimate their
lattice constants and spontaneous polarization. Conversely, non-local van der Waals functionals with C09 exchange accurately capture these properties compared to experiment, but with a larger computational overhead than, for example, GGA. We show that C09x-PBEc combines the accuracy provided by the C09 exchange with the computational affordability of GGA, making it an excellent candidate to be used in the training of MLIPs for ferroelectric perovskites. We also demonstrate that an MLIP trained using C09x-PBEc accurately reproduces the ferroelectric-to-paraelectric phase transition temperature of PbTiO3 with respect to experiment, showing a marked improvement on MLIPs trained using GGA.
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Earth and Planetary Astrophysics
Spatial distribution of water ice in the protoplanetary silhouette disk d216-0939
J. S. Martin, S. Wolf, A. Potapov et al. (+4 more)
The composition of rocky
planets depends on the
dust in their natal protoplanetary disk (PPD), potentially containing water ice. Crystalline water ice was detected in the PPD d216-0939 in the Orion Nebular Cluster (ONC). We aim at constraining the spatial distribution and crystallization state of water ice in the d216-0939 disk using recent observations of the water ice absorption feature at a wavelength of $\sim 3\mathrm{\mu m}$ collected with JWST. We perform 3D Monte Carlo radiative transfer (MCRT) simulations to constrain the free parameters of an
accretion disk model by fitting the calculated spectrum in the wavelength range from $1.6 \text{ to } 24\mathrm{\mu m}$ to the spectral energy distribution (SED) observed with the JWST instruments NIRSpec and MIRI. Additionally, archival, spatially resolved HST observations were used to constrain the global spatial structure of the disk, as the parameter space is degenerate with respect to the fit to the SED. Successively, we fit the water ice absorption feature using polychromatic MCRT simulations with spectral importance sampling to produce synthetic observations at high spectral resolutions. By probing the upper and outer disk layers, we found that a PPD model with
dust containing 5.4% crystallized water ice beyond the snowline fits the observations well, necessitating outward transport of material, since crystalline ice is unlikely to form in situ in the probed disk layers. In the spectral region of the water ice absorption feature, scattering and thermal
dust emission both contribute significantly to the total flux.
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All authors J. S. Martin, S. Wolf, A. Potapov, H. Linz, Th. Henning, H. Terada, M. B. Michaelis
High Energy Physics (Phenomenology)
Isochrone fitting of Galactic globular clusters - IX. Tip of the red-giant branch for 27 clusters and constraints on new particle physics
G.A. Gontcharov, A.M. Kudashov, O.S. Ryutina et al. (+1 more)
Red-
giant evolution is sensitive to non-standard channels of energy loss in
stellar cores and therefore provides a probe of new physics. Such losses increase the luminosity of the tip of the red-
giant branch (TRGB), the brightest point reached by a red
giant in the color-magnitude diagram. Previous analyses of TRGB luminosities in globular clusters placed stringent bounds on the
axion-electron coupling g_{ae}, but were limited by observational and theoretical uncertainties. To obtain a homogeneous and systematically controlled constraint, we use new parameters and TRGB estimates for 27 globular clusters, derived from Stetson, Hubble Space
Telescope, and
Gaia photometry, together with cluster-specific MESA calculations. Our primary likelihood uses 24 clusters after excluding three hot-flasher systems and explicitly accounts for
stellar variability in identifying the brightest RGB
stars. Finite sampling of the upper RGB is described by the full conditional distribution, and shared observational and
stellar-physics uncertainties are retained as correlated nuisance parameters. The observed TRGB is fainter than the standard-cooling prediction by 0.078 (+0.036,-0.037) mag; to avoid an artificially strong bound from this downward fluctuation, we use the power-constrained profile likelihood method and obtain g_{ae}<6.4e-14 (95% CL). Sensitivity estimates for the
neutrino magnetic dipole moment and for millicharged particles are also presented.
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All authors G.A. Gontcharov, A.M. Kudashov, O.S. Ryutina, S.V. Troitsky
Quantum Physics
High-cooperativity coupling and spin-resolved extinction of tin-vacancy centers in a diamond-like microcavity
Kerim Köster, András Laukó, Federico Rapisarda et al. (+16 more)
The tin-vacancy (SnV) center in diamond is a promising
spin-
photon interface for
quantum networks, combining favorable optical properties with
spin coherence above 1K. Unfolding the full potential requires cavity enhancement to increase
photon-emitter coupling efficiency. Here, we demonstrate cavity-enhanced light-matter coupling of SnV centers in a fully tunable Fabry-Pérot microcavity operating at temperatures down to 1K with in-situ
magnetic field control. We access the diamond-like regime of hybrid cavity modes through integration of low-roughness diamond membranes, where the field is concentrated inside the diamond and Purcell enhancement is maximized. Diamond-like modes deliver a more than two-fold increase in the effective Purcell factor over air-like modes, reaching $C_0 = 4.1(1)$ compared to $C_0 = 1.85(5)$ in the air-like case, while simultaneously relaxing mechanical stability requirements. Resonant probing reveals coherent cavity-emitter coupling with 96% extinction contrast and a coherent cooperativity of $C = 4.0(14)$. By applying a
magnetic field, we further achieve
spin-resolved cavity extinction, observing
spin-selective optical transitions with a contrast of ${\cal C}_{\rm spin} = 0.91$. These results establish SnV centers in diamond coupled to open Fabry-Pérot microcavities as a promising platform for efficient
spin-
photon interfaces.
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All authors Kerim Köster, András Laukó, Federico Rapisarda, Philipp Graßhoff, Vladislav Bushmakin, Jens Fuhrmann, Ou Wang, Dominic Reinhardt, Doğuşcan Ahiboz, Peter Knittel, Thomas Hümmer, Wolfgang Wernsdorfer, Jörg Wrachtrup, Fedor Jelezko, Tommaso Pregnolato, Tim Schröder, Jan Meijer, Cyril Popov, David Hunger
Mathematical Physics · Cross-listed from math.DS
An Inverse Theorem for Partially Symmetric Two-Dimensional Semiclassical Schrödinger Operators
Kuo Wang
We study a two-dimensional semiclassical Schrödinger operator whose potential admits one reflection
symmetry. Under a rational independence assumption on the harmonic frequencies and a nonvanishing condition \(a_{30}\ne0\), we show that the first two layers of the
quantum Birkhoff normal form, together with the sign of \(a_{30}\) and the transverse data \(\{a_{1,2k}\}_{k\ge1}\), determine the Taylor series of the potential at the bottom of the well. The proof is constructive: the \(\hbar^2\)-layer gives a triangular recursion for odd-degree terms, while the classical layer recovers even-degree terms from their resonant projections.
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Superconductivity
Yiming Zhang and Samuel Poncé
We performed a first-principles high-throughput screening of the mechanical properties of
phonon-mediated
superconductors selected from the recent experimentally synthesized superconducting materials database PRX Energy 4, 033012 (2025). We developed the workflows that combine first-principles calculations of elastic constants and generalized stacking fault energies to assess the ductility of superconducting candidates. Starting from the 250 materials identified with promising superconducting critical temperatures, we computed their elastic tensors to evaluate bulk and shear
moduli, Pugh's ratio, and Pettifor's ratio from first principles. To further characterize their plastic deformation behavior, we calculated the stacking fault energy and surface energy for selected materials and slip directions, allowing the estimation of Rice's ratio and ductility indicators. We found that several new materials simultaneously exhibit high-T$_c$ and ductility including HfPd$_2$Al, TiRuSb, and ZrNi$_2$Ga with predicted isotropic T$_c$= 6.80K, 12.88K, and 8.23K, respectively. This work offers a quantitative mapping of mechanical performance across a wide range of
superconductors and provides a reference to identify new mechanically promising
superconductors.
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Astrophysics of Galaxies
Inflow-driven galaxy evolution - I. Revealing the physics of the fundamental metallicity relation
Kai Wang, Carlton Baugh, N. F. Boardman et al. (+11 more)
We present a unified physical framework for the fundamental
metallicity relation (FMR), based on the mass-continuity equations. The FMR is not merely the anti-correlation between
star formation rate (SFR) and gas
metallicity ($Z_{\rm g}$) at fixed
stellar mass ($M_\star$); it is a
redshift-invariant surface in the $(M_\star,{\rm SFR},Z_{\rm g})$ space. We construct a minimal cosmological gas flow model, calibrated to reproduce the mass-
metallicity relation,
star-forming main sequence, and
stellar-to-
halo mass relation at $z=0-3$, and show that the FMR emerges as a prediction of the calibrated physics. Through controlled experiments that progressively simplify the model, we reveal that in a universe where both the
star formation efficiency ($\epsilon$) and mass-loading factor ($\eta$) are constants, the FMR reduces to a universal scaling between $Z_{\rm g}$ and $M_\star/$SFR, whose shape traces the transition from inflow-driven regime to
equilibrium. The specific parameterisation of the observed FMR is not a fundamental
symmetry but a contingent consequence of how $\epsilon$ and $\eta$ depend on
stellar mass and
redshift. We show that the gaseous FMR (gFMR), defined in the $(M_\star,M_{\rm g},Z_{\rm g})$ space, is more fundamental than the standard FMR: in the inflow-driven limit, $Z_{\rm g}$ is proportional to $M_\star/M_{\rm g}$, and the approach to
equilibrium is governed by $M_\star/M_{\rm g}$ and $\eta$ alone. We derive an analytic solution for an idealised version of the model that provides closed-form expressions relating $Z_{\rm g}$, $M_{\rm g}/M_\star$, and $\eta$, and show this framework accurately reproduces the cosmological gas flow model. By establishing the physical origin of the FMR and its connection to the more fundamental gFMR, we provide the theoretical foundation to turn
metallicity scaling relations into precision probes of the
baryon cycle over
cosmic history.
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All authors Kai Wang, Carlton Baugh, N. F. Boardman, Sownak Bose, Zheng Cai, Shaun Cole, Carlos S. Frenk, Cedric Lacey, Peder Norberg, Yingjie Peng, Isabel Santos-Santos, Amélie Saintonge, Tom Theuns, Enci Wang
Strongly Correlated Electrons
Lifting the degeneracy of quantum spin liquid phase by uniaxial pressure
Shams Sohel Islam, Zurab Guguchia, Orion Gerguri et al. (+13 more)
We report
muon spin relaxation/rotation ($\mu$SR) measurements of the candidate three-dimensional (3D)
quantum spin liquid (QSL) PbCuTe$_2$O$_6$, hosting $S=1/2$ moments, under controlled in situ [110] uniaxial compression up to $\sigma_{[110]}=37.7$~MPa. A small directional
lattice perturbation significantly modifies the local
magnetic response, while above $\sigma_{\rm cr}\sim10.8$\,MPa the relaxation rates are strongly enhanced and the internal-field distribution is substantially broadened. These changes occur along with the local crystalline
symmetry breaking. While, no evidence for conventional static long-range
magnetic order is observed, the compression drives the system towards a structurally modified and strongly correlated state in which enhanced quasi-static correlations coexist with persistent slow
spin dynamics. This work demonstrates a clean and
symmetry-selective route to control frustrated exchange landscape and access hidden
magnetic instabilities in a 3D QSL candidate opening up the possibilities to tune other correlated systems where intrinsic coupling between
magnetic and
lattice degrees of freedom are relevant.
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All authors Shams Sohel Islam, Zurab Guguchia, Orion Gerguri, Petr Král, Maxime Lamotte, Toni Shiroka, Jonas A. Krieger, Thomas J. Hicken, Tina Arh, Gediminas Simutis, Abanoub Hanna, Nazmul Islam, Bella Lake, Hubertus Luetkens, Hans Henning Klauss, Rajib Sarkar
Materials Science
A phase field model of coupled crack and dislocations: emission, blunting, and the necessity of dissipative toughening
Khanh Chau Le and Thi My Kieu Tran
We propose a phase field model of a macrocracked single
crystal in which the crack and the geometrically necessary dislocations descend from a single energy functional. Energy minimization alone then decides dislocation nucleation, through an integral criterion evaluated in closed form along slip chords. The criterion yields a size effect inaccessible to point-wise strength conditions: a grain-size-dependent yield stress. With slip suppressed the model reproduces Griffith fracture; with fracture suppressed, the nucleation load measured by the full non-smooth solver agrees with the closed-form nucleation criterion to four percent. The coupled computations produce a two-stage response: at loads an order of magnitude below cleavage, dislocation bands emitted from the notch tip blunt and shield it, raising the initiation load; once the crack grows, the bands heal; a compact cluster of like-signed dislocations travels with the tip, its canceling partner walls pinned at the grain boundary, and the dissipated fracture resistance equals the elastic one. In the purely energetic, dissipationless limit, emission shields the crack but does not toughen it; toughening requires dissipation, incorporated in the sequel through the threshold resistance to dislocation motion.
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Quantum Physics
Demonstrating advantages of dynamic quantum circuits on a hybrid superconducting qubit-cavity processor
Hongbo Wu, Ling Hu, Jiasheng Mai et al. (+10 more)
Dynamic
quantum circuits (DQCs) provide a hardware-efficient route to
quantum computing by reducing physical-
qubit overhead and compressing
circuit topology through mid-
circuit measurements,
qubit reset and reuse, and classical feed-forward control. Here, we demonstrate the advantages of DQCs on a single hybrid superconducting
qubit-cavity processor by implementing a hierarchy of
algorithms with increasing complexity. This hybrid architecture consists of a high-dimensional cavity qudit serving as the computational register and a dispersively coupled superconducting transmon ancilla that is repeatedly measured, reset, and reused to enable dynamic control. Using this device, we implement a 10-bit Bernstein-Vazirani
algorithm with an average success probability of 82%, surpassing state-of-the-art dynamic and static implementations in both scale and performance; an 8-bit
quantum phase-estimation protocol with estimation errors below 10-3; and the first dynamic-
circuit implementation of Shor's
algorithm on a superconducting platform, factoring 15 over all coprime bases with squared statistical overlap values above 99.8%. These results provide concrete
benchmarks for future DQC implementations and highlight the versatile advantages of DQCs with the hybrid
qubit-qudit architecture, establishing it as a promising route toward scalable, programmable
quantum computation.
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All authors Hongbo Wu, Ling Hu, Jiasheng Mai, Munan Zhang, Libo Zhang, Yanyan Cai, Xiaowei Deng, Pan Zheng, Zhongchu Ni, Song Liu, Kun Fang, Dapeng Yu, Yuan Xu
Quantum Physics
Constructive realization of self-referential prediction limits in quantum control: Resource bounds and Gödel-safe architectures
Salman Sajad Wani, Álvaro Perales-Eceiza, Saif Al-Kuwari et al. (+1 more)
Programmable
quantum control systems increasingly rely on predictive modules for certification, real-time feedback, and autonomous decision-making. This development raises a fundamental question: can self-analyzing
quantum platforms universally predict their own experimental outcomes? Wolpert formalized a general impossibility of universal self-prediction. Here we translate that limitation into an explicit laboratory obstruction that can be realized with finite resources. We consider settings with programmable
quantum control in which predictors can be embedded as subroutines within the experiments they analyze. Our diagonal construction uses Kleene's recursion
theorem to transform any deterministic bounded-time predictor into a reversible protocol encoding its own specification. The resulting protocol invokes the predictor on that specification and deterministically produces a classical pointer record that contradicts the forecast. For efficient predictors, the compilation has
polynomial overhead and admits concrete physical realizations as a fault-tolerant
quantum circuit and as a minimal Mach-Zehnder interferometer. These realizations connect computability-theoretic self-reference to programmable
quantum hardware. We also introduce and formally define Gödel-safe architectures. These architectures block the forbidden causal path from the protocol description to an actuator that can affect the pointer during the same run. We analyze their implications for real-time
quantum error correction, including the resulting expressiveness trade-offs. As
quantum control loops grow in computational expressiveness, the limits of self-reference cease to be mere mathematical abstractions and become explicit engineering constraints for the reliable operation of autonomous
quantum technologies.
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All authors Salman Sajad Wani, Álvaro Perales-Eceiza, Saif Al-Kuwari, Mir Faizal
Quantum Physics
From normal Lindbladians to non-normal quantum trajectories
Shakib Daryanoosh
Efficient simulation of Markovian open
quantum systems remains a central challenge because the density-
matrix description grows exponentially with system size.
Quantum trajectory methods provide an alternative by replacing mixed-state
evolution with
stochastic pure-state realizations. Here we investigate this framework for normal Lindblad generators, whose orthogonal eigenoperator decomposition precludes transient amplification. By decomposing the Lindbladian into deterministic smooth and
stochastic jump contributions, we derive an exact steady-state balance relation that identifies the interplay between these processes as the mechanism underlying Liouvillian normality. We further show that normal Lindbladians exclude exceptional points and that, although individual
quantum trajectories generally exhibit
stochastic coupling between Liouvillian eigenmodes, these couplings cancel upon ensemble averaging, recovering independent orthogonal relaxation modes. These results provide a trajectory-level interpretation of Liouvillian normality and clarify how a global property of the Lindblad generator is realized through
stochastic quantum dynamics.
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Solar and Stellar Astrophysics
Cepheid metallicities from low-resolution near-infrared spectra: validation against the optical reference scale
M. A. Urbaneja, R. P. Kudritzki and N. Przybilla
Classical Cepheid
metallicities trace recent chemical enrichment and help assess systematics in Cepheid-based distance measurements. They are derived mainly from high-resolution optical spectroscopy, which provides the
benchmark abundance scale but limits measurements to nearby systems. Extending such studies to more distant Cepheids with extremely large
telescopes requires complementary low-resolution near-infrared methods and careful treatment of model–data residuals. We test whether low-resolution SpeX/IRTF Y+J-band spectra can yield
metallicities compatible with homogenised optical abundances. We analyse 14
Galactic classical Cepheids with periods of approximately 13–69 d, supplemented by two shorter-period
stars from the IRTF Spectral Library. Using
Bayesian full-spectrum fitting based on MARCS/TURBOSPECTRUM spectra and a regularised covariance likelihood, we infer [M/H] and compare it with homogenised optical [Fe/H]. For the primary 14-
star sample, the inferred
metallicities reproduce the optical reference scale with a mean offset of -0.05 dex, a scatter of 0.09 dex, and a robust scatter of 0.12 dex; the median posterior uncertainty is 0.22 dex. Including the two additional
stars changes these values only slightly. Compared with a diagonal likelihood, the covariance-aware treatment reduces the mean offset and improves the stability of the uncertainty calibration. Low-resolution Y+J spectra therefore contain usable
metallicity information for classical Cepheids when short-range correlated residuals and localised modelling imperfections are treated explicitly. The resulting near-infrared
metallicity scale provides a practical foundation for extending Cepheid
metallicity work to larger and more distant samples.
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Cosmology and Nongalactic Astrophysics
Is Dark Matter Really Matter?
Jun-Qian Jiang and Arman Shafieloo
In the standard model of cosmology, it is assumed that dark matter is pressureless with equation of state $w=0$ and dark energy has $w=-1$. We test these assumptions jointly using DESI DR2 distance measurements, including the recent Lyman-$\alpha$ full-shape Alcock-Paczynski (AP) information, DES
supernovae, and two complementary CMB treatment. When constant $w_{dm}$ and $w_{de}$ are varied together, we find $w_{dm}=0.000968^{+0.000501}_{-0.000496}$ and $w_{de}=-0.9380^{+0.0259}_{-0.0262}$ (68%). With an alternative CMB treatment that marginalizes over the
lensing spectrum, the corresponding constraints are $w_{dm}=0.000870^{+0.000408}_{-0.000410}$ and $w_{de}=-0.9353^{+0.0258}_{-0.0254}$. Both standard $\Lambda$CDM values are disfavored at approximately $2\sigma$ in the joint extension. Neither parameter departs significantly from its standard value when only that parameter is varied. This behavior arises because late-time distances favor $w_{de}>-1$, while maintaining the early-Universe physical matter density requires a compensating positive $w_{dm}$, which changes the mapping to the matter density today. Allowing dynamical dark energy further highlights the complexity of the situation: phantom crossing for dark energy makes $w_{dm}=0$ consistent with the data, whereas a positive $w_{dm}$ preference persists when crossing is forbidden. Interestingly, the Pad'e-$w$ parameterization that provides a flexible description of a class of quintessence models (with no phantom crossing), along with $w_{dm}$ free, is even mildly favored over the phantom-crossing $w_0w_a$ model according to both the best-fit $\chi^2$ and the DIC under both CMB treatments. One can conclude that the apparent preference for phantom crossing may instead reflect deviations in the dark-matter sector rather than dark-energy dynamics alone. [abridged]
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Disordered Systems and Neural Networks
Emergent Replica Clock Unifies Many-Body Localization and Thermalization
Tong Liu
Many-body localization (MBL) and eigenstate thermalization (ETH) are traditionally distinguished by a collection of separate diagnostics, not by a single order parameter. We show that replication and folding of isolated
unitary dynamics generate a complex statistical mechanics of forward–backward history pairings and, in a closed cyclic infrared sector, an emergent clock $r_x\in\mathbb Z_t$. Its correlator has three distinct asymptotics: exponential decay in MBL, scale-free decay at criticality, and long-range locking in the thermal phase. A controlled $l$-bit reduction makes the clock action quasi-local, while its inverse correlation length obeys $\xi_{\rm pair}^{-1}=\kappa_{\rm el}=\ln|\rho_0/\rho_q|$, unifying history coherence, the defect line tension, and the transfer spectrum. Replica order supplies a second, discrete coordinate—the first order at which a hidden dynamical invariant becomes visible—and can distinguish localized dynamics that share the same spatial correlation length.
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Nuclear Experiment
News on charged and neutral hadron production from NA61/SHINE
Yuliia Balkova and Maciej P. Lewicki
Strangeness production in high-energy hadronic and
nuclear collisions remains a central topic in the study of strongly interacting matter under extreme conditions. The data collected by the NA61/SHINE experiment at the CERN SPS allow for a comprehensive scan of
hadron production across various collision energies and system sizes. This article focuses on new results on charged and neutral
hadron production in central collisions of medium-sized
nuclei, such as Ar+Sc and Xe+La, in the SPS energy range. First, the energy and system-size dependence of the $K^+/\pi^+$ ratio is discussed, confirming the “horn” structure in central Pb+Pb collisions and its absence in smaller systems. Furthermore, the inverse slope parameter $T$ of kaon transverse mass (transverse momentum) spectra is analyzed, showing that intermediate-size systems reach values comparable to those observed in central Pb+Pb collisions. Second, normalized
proton rapidity spectra $(\text{d}n/\text{d}y)/\langle W \rangle$ in central Be+Be, Ar+Sc, and Pb+Pb collisions are presented, demonstrating energy-dependent
baryon transport as a function of system size. Building on this baseline, $\Lambda$ hyperon production in central Ar+Sc collisions is explored across SPS energies, where rapidity spectra, mean multiplicities ($\langle \Lambda \rangle$), and ratios to pions are compared with model predictions and existing data. Finally, an anomalous excess of charged over neutral kaons ($R_K > 1$) in central Ar+Sc collisions is reported, highlighting a potential unexpectedly large violation of isospin
symmetry.
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Cosmology and Nongalactic Astrophysics
Non-Thermal Pressure due to Gas Motions in the Intracluster Medium: Confronting XRISM/Resolve with TNG-Cluster Simulations
Erwin T. Lau, Naomi Ota and Daisuke Nagai
Intracluster medium (ICM) gas motions probe cluster assembly, feedback, and non-thermal pressure support, but recent XRISM observations reveal velocity dispersions and non-thermal pressure fractions systematically lower than simulations predict, with extreme systems such as Abell 2029 falling below nearly all simulated clusters. Using the TNG-Cluster simulations, we show that the non-thermal pressure fraction depends sensitively on cool-core state and formation history, and provide a two-scale fitting function capturing both the inner cool-core suppression and outer rise of the radial profile. By forward-modeling mock XRISM observations and comparing them with both projected and intrinsic three-dimensional quantities, we find that azimuthal variations and projection effects contribute to the deficit in the observed velocity dispersion and non-thermal pressure fraction. This bias increases with radius and partially offsets the intrinsic outward rise in the true three-dimensional non-thermal pressure fraction. However, these effects cannot explain the extremely low values of the non-thermal pressure fraction observed in Abell 2029, which fall below approximately the 0th-6th percentiles of the simulated cool-core cluster distribution at every measured radius under both the
turbulence-only and
turbulence-plus-bulk definitions. The remaining tension points to rare dynamical conditions or missing physics affecting the amplitude of gas motions in current ICM models.
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Materials Science
Unifying microscopic theories for the phono-magnetic effect
Natalia Shabala, Finja Tietjen, Ylva Liljegren et al. (+1 more)
Phonon angular momentum induces an effective
magnetic field, a phenomenon called phono-
magnetic effect, which has been measured to vary significantly in size. Here, we compare three approaches for deriving the effective
magnetic field of a
phonon, using electron-
phonon coupling and orbital magnetism. The adiabatic approach assumes a slow ionic motion, keeping electrons in the ground state. The perturbative approach treats the electron-
phonon interaction as a perturbation to the electronic ground state, and the Floquet approach is based on the time-periodicity of the circular ionic motion. We show that all three approaches lead to the same effective
Hamiltonian in the low-frequency limit, which moves us closer towards a unified theory of the phono-
magnetic effect. Furthermore, we identify two phononic contributions to the sample magnetization, spontaneous and induced. Thus, we clarify the role of the effective
magnetic field in the
phonon-induced magnetization. We conclude by providing a numerical estimate for the effective
magnetic field in SrTiO$_3$.
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All authors Natalia Shabala, Finja Tietjen, Ylva Liljegren, R. Matthias Geilhufe