Atmospheric and Oceanic Physics
Predictability of El Niño from Delayed Observations
Francisco J. Beron-Vera
Using monthly Niño-3.4 anomalies through July 2026, we investigate how much predictive information is contained in delayed observations of the index. Ridge regression identifies informative delays, while multilayer perceptron and sparse identification of nonlinear dynamics (SINDy) models test whether nonlinear complexity provides additional direct forecast skill; gated recurrent unit (GRU) and long short-term
memory (LSTM) networks provide a complementary test in which the temporal representation is learned internally. Delayed observations substantially improve forecasts over persistence and climatology at leads of up to six months, but increasing model complexity provides no systematic improvement. Historical recursive experiments favor a simple explicit SINDy recurrence and select shallow recurrent architectures, with no appreciable gain from learning the temporal representation internally. These results support a compact predictive representation of Niño-3.4
evolution in which the representation of past information is more consequential than model complexity. As a prospective application, the selected models are used to forecast the developing 2026 event beyond the last available observation and to compare its predicted
evolution with completed historical El Niño events.
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Mathematical Physics
Joint moments of characteristic polynomials in the circular Jacobi ensemble and Painlevé equations
Thomas Bothner and Fei Wei
In this paper, we establish a connection between joint moments of characteristic
polynomials and their derivatives in the Circular Jacobi Ensemble, a generalisation of the Circular
Unitary Ensemble, and solutions of nonlinear Painlevé equations. For finite $N$, we show that these joint moments are characterised by a solution of the $\sigma$-Painlevé V equation for all real moment exponents in their admissible range. Under an appropriate large-$N$ scaling limit, we further prove that the limiting joint moments admit a representation in terms of a solution of the $\sigma$-Painlevé III$'$ equation for a certain range of moment exponents. As applications, we answer a question posed by Assiotis et al. in [Math. Physics. Anal. Geom. 25 (2022), no.2, Paper No. 15, 24pp, Remark 1.7] by showing that the characteristic function of a distinguished random variable is connected with the $\sigma$-Painlevé III$'$ equation for complex parameters. Furthermore, we investigate joint moments involving higher-order derivatives of characteristic
polynomials in the Circular Jacobi Ensemble. As a consequence, we extend a result of Assiotis et al. in [Comm. Pure Appl. Math. 79 (2026), no. 7, 1771-1827,
Theorem 1.11] concerning the joint moments of a sequence of random variables arising from the ergodic decomposition of Hua-Pickrell measures, from real parameters to complex parameters.
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Materials Science
A colossal dielectric response of Bi1-xSmxFeO3 nanopowders
Vladyslav O. Kolupaiev, Olexander S. Pylypchuk, Vladimir N. Poroshin et al. (+6 more)
The dielectric permittivity of the pressed powder samples of Bi1-xSmxFeO3, with Sm content "x" varying in the range 0 - 0.2, has been investigated in the temperature range from 20 to 400 C and the frequency range from 100 Hz to 100 kHz. We have shown that the Sm content impacts significantly the real and imaginary parts of effective dielectric permittivity, which have expanded diffuse maxima with a colossal magnitude up to 105 (for the real part) and up to 108 (for the imaginary one) at temperatures 300 - 400 K. Analysis of experimental data carried has shown that both the real and imaginary parts of effective dielectric permittivity may be comprehensively explained by considering a complex interplay of a diffuse ferroelectric-paraelectric phase transition and the Maxwell-Wagner-Sillars effects, which emerge from the formation of spatial charges at interfaces between nanograins and at the ferroelectric nanoparticle-air interface. Processing of experimental data for the real and imaginary parts of the effective dielectric permittivity within effective medium approach allows us to separate and analyze the colossal dielectric response of the nanoparticles itself. The main trends followed from experiments are supported by the theoretically simulated dependences, which reveal correlations between the temperature behavior of dielectric properties and phase state of the Bi1-xSmxFeO3 nanoparticles.
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All authors Vladyslav O. Kolupaiev, Olexander S. Pylypchuk, Vladimir N. Poroshin, Denis O. Stetsenko, Ihor V. Fesych, Lesya D. Demchenko, Eugene A. Eliseev, Victor V. Vainberg, Anna N. Morozovska
Cosmology and Nongalactic Astrophysics
The Primordial power spectrum from the largest to smallest CMB scales
Debabrata Chandra, Dhiraj Kumar Hazra, Arman Shafieloo et al. (+1 more)
We reconstruct the
primordial power spectrum (PPS) across the full range of cosmological scales accessible to
Cosmic Microwave Background (CMB) observations. Using the Modified Richardson–Lucy
algorithm, we perform free-form reconstructions through deconvolution of Planck PR3 and PR4, Atacama Cosmology
Telescope (ACT) DR6, and South Pole
Telescope 3G (SPT-3G) D1 data. Across different regularization schemes, we find no evidence for significant deviations from a power-law
primordial spectrum. The reconstructed spectra show a strong correlation between Planck and ACT, even at the level of localized features over their overlapping range, $0.07 < k < 0.14\,\mathrm{Mpc}^{-1}$, demonstrating consistency between the two observations. Using a complementary parametric
Bayesian reconstruction, we find that the previously discussed preference for a blueward tilt in the ACT data at small scales is preferred only at the $1\sigma$ level.
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All authors Debabrata Chandra, Dhiraj Kumar Hazra, Arman Shafieloo, Tarun Souradeep
Quantum Physics
Towards Stirling cooler operable single-photon sources based on low-noise GaAs quantum dots
Maximilian Aigner, Jana Schlücking, Eva Schöll et al. (+15 more)
For photonic
quantum technology applications, sources capable of emitting
photons with indistinguishability close to unity are essential. Ideally, these sources should not require demanding cooling systems. Here, we present temperature-dependent two-
photon-interference measurements on
photons produced by the radiative decay of the negative trion in a low-noise GaAs
quantum dot, which are in quantitative agreement with theoretical calculations accounting for carrier-
phonon interactions and coupling to excited states. While at at the lowest explored temperatures the emission linewidth reaches values only 6(2) % above the
Fourier limit and the indistinguishability I between subsequently emitted
photons reaches 0.966(6), the latter drops to 0.05(4) at 55 K. We show that this loss can be explained with the coupling with energetically close excited trion states and suggest that the
photon indistinguishability at elevated temperatures can be increased by employing Purcell enhancement of the emission rate or by increasing the energy separation of the excited states. Using cavity-enhanced emission, we experimentally verify the first route and demonstrate an improvement in
photon indistinguishability from 0.314(25) to 0.80(3) at 32 K, which - to our knowledge - is the highest reported value at such temperature.
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All authors Maximilian Aigner, Jana Schlücking, Eva Schöll, Christian Weidinger, Gabriel Undeutsch, Ievgen Brytavskyi, Thomas Oberleitner, Tobias Maria Krieger, Ailton Jose Garcia Junior, Melina Peter, Thomas K. Bracht, Michał Gawełczyk, Saimon Filipe Covre da Silva, Santanu Manna, Yusuf Karli, Gregor Weihs, Doris E. Reiter, Armando Rastelli
Strongly Correlated Electrons
Altermagnetic Anomalous Hall Effect and Spin–Edge-Locked Chiral Modes in a Modified Kane–Mele–Hubbard Model
Mohsen Hafez-Torbati and Alireza Qaiumzadeh
We establish a correlation-driven route to the altermagnetic anomalous
Hall effect (AHE) and its associated
spin–edge-locked edge states in a modified Kane–Mele–Hubbard model. Using dynamical mean-field theory (DMFT), we show that, at half-filling, increasing the Hubbard interaction drives the system from a metallic paramagnetic phase hosting antichiral edge states into an insulating in-plane Néel-type
antiferromagnetic phase, in which a residual antiunitary
symmetry forbids the AHE. Hole doping induces a
spin-flop transition to an out-of-plane Néel-type
antiferromagnetic phase, thereby breaking this
symmetry and generating a finite anomalous
Hall conductivity that persists into the strongly correlated regime. Distinct from a conventional
spin-polarized
Hall response in ferromagnets, the altermagnetic AHE receives equal and additive contributions from the two
symmetry-related
spin sectors and is accompanied by
spin–edge-locked
chiral states. Our results demonstrate that carrier doping and
spin-rotationally invariant Hubbard interactions are sufficient to realize the altermagnetic AHE, without invoking an explicitly Ising-like interaction, and provide a realistic microscopic route toward its realization in correlated transition metal dichalcogenides monolayers.
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Earth and Planetary Astrophysics
Volatile depletion in rocky planets as a chemical fingerprint of hybrid accretion
Haiyang S. Wang, Anders Johansen, Ziyan Xu et al. (+7 more)
Volatile depletion in rocky
planets relative to their host
stars is commonplace in both the
Solar System and exoplanetary systems, yet the connections between
planet formation and composition remain elusive. Here we model devolatilization during pebble
accretion in combination with collisional growth from volatile-depleted planetesimals to explore the formation pathways of Earth and Mars. Using
Bayesian inference, we find that bulk silicate Earth is best reproduced by ${\gtrsim}$75% contribution from two protoplanets formed via pebble
accretion, supplemented by up to $\sim$25% material from planetesimals that are compositionally akin to the asteroid Vesta. Using instead a planetesimal volatile-depletion curve that is not observed among known meteorite parent bodies would allow the planetesimal contribution to reach 40$^{+15}_{-14}$%. In comparison, bulk silicate Mars reflects 27$\pm$5% pebble-accreted material and 73${\pm}$5% Vesta-like planetesimals. We identify volatile depletion as a chemical fingerprint of hybrid
accretion, in which both pebble
accretion and collisional assembly contribute to terrestrial
planet growth. By quantitatively linking formation pathways to volatile budgets, our findings demonstrate how planetary
accretion histories can be inferred from elemental signatures, with broad implications for interpreting the chemical diversity of rocky
exoplanets.
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All authors Haiyang S. Wang, Anders Johansen, Ziyan Xu, Marie-Luise Steinmeyer, Michiel Lambrechts, Elishevah van Kooten, Chao-Chin Yang, Zhaohuan Zhu, Dante S. Lauretta, Martin Bizzarro
High Energy Physics (Phenomenology)
Hyperfine Mixing and Final-Spin Redistribution in Inclusive $\Xi_{bc}\to H_{cc}+X$
Ishtiaq Ahmed
In this work, we study the effect of hyperfine mixing on the inclusive weak transition $\Xi_{bc}\to H_{cc}+X$, which has been proposed as a useful channel for searching for beauty-charmed
baryons. Starting from the inclusive heavy-diquark framework, we include mixing between the scalar and axial-vector $bc$ configurations and decompose the final doubly charmed system into the $J_f=1/2$ and $J_f=3/2$
spin sectors. Within a minimal scalar-to-axial transition model, and for a
benchmark scalar-channel normalization of order unity at zero
recoil, we find that the interference between the scalar and axial components is large in the separate
spin sectors but cancels after summing over the two members of the adopted ground-state $ccq$
spin multiplet, $\Gamma_{AS}^{1/2}=-\Gamma_{AS}^{3/2}$. Consequently, the
spin-summed inclusive rate is less sensitive to hyperfine mixing than the direct ground-state contribution, provided feed-down from the
spin-excited $\Xi_{cc}^{*}$ partner is experimentally unresolved. For a scalar-channel normalization of order unity, the direct contribution can be strongly
spin selective: $\Xi_{bc}^{(1)}$ dominantly feeds the $J_f=1/2$ $\Xi_{cc}$ channel, whereas $\Xi_{bc}^{(2)}$ dominantly feeds the $J_f=3/2$ $\Xi_{cc}^{*}$ sector. We test this pattern for several convention-matched literature admixtures and for a separately labeled decay-interference diagnostic angle, together with the dependence on the scalar-to-axial normalization and
recoil-shape choice. The cancellation of the
spin-summed interference is a consequence of
baryon spin recoupling within the spectator and common-multiplet assumptions, whereas the magnitude of the
spin selectivity is conditional on the magnitude and relative phase of the scalar-to-axial transition.
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Chemical Physics
Quantum Vibronic Dynamics Shape Catalytically Relevant Au-Ligand Interfaces in Atomically Precise Gold Nanoclusters
Mengyuan Cui, Tianrui Chen, Junhua Zhou et al. (+6 more)
Atomically precise gold nanoclusters are versatile for photocatalysis and energy conversion because their electronic structure stems from strong metal-ligand interactions. However, these interactions are mostly discussed statically, leaving dynamic reorganization of Au-ligand interfaces under photoexcitation unclear. We investigate rod-shaped [Au25(PPh3)10(SC2H5)5Cl2]2+ using ultrafast transient-grating spectroscopy, two-dimensional electronic spectroscopy, ab initio calculations, and hierarchical equations-of-motion simulations. The multidimensional spectra resolve multiple electronic relaxation pathways and a hierarchy of coherent structural motions, from localized Au-ligand distortions to collective framework vibrations. Wavelet analysis reveals that high-frequency Au-ligand vibrations emerge immediately after excitation, whereas low-frequency collective modes appear later through interstate vibronic coupling, indicating sequential redistribution of structural coherence. Simulations reproduce the nonlinear response and identify the microscopic vibronic couplings responsible. The results show that photoexcitation drives continuous ultrafast reorganization of the Au-ligand bonding network, transiently reshaping interfacial electronic structure before thermalization. This work establishes dynamic Au-ligand interfaces as the microscopic link between excited-state energy flow and photochemical function in atomically precise nanoclusters.
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All authors Mengyuan Cui, Tianrui Chen, Junhua Zhou, Xiangmei Duan, Vandana Tiwari, Chao Mei, Ajay Jha, Fulu Zheng, Hong-Guang Duan
High Energy Astrophysical Phenomena
Fingerprints of thermal Comptonization in accreting neutron stars. Plasma-vacuum interplay in cyclotron lines and polarisation
E. Sokolova-Lapa, D. K. Maniadakis, J. J. R. Stierhof et al. (+11 more)
X-ray emission from accreting, strongly magnetised
neutron stars and its pulse-phase variability probe their
magnetic-field geometry,
spin orientation, and emission processes. Whether the radiation emerges mainly from a hot spot or column, and whether its properties are shaped by bulk or thermal Comptonization, remain debated across luminosity regimes. We aim to disentangle intrinsic emission from visibility effects and identify observables characteristic of thermal Comptonization in hot spots and columns. We therefore derived energy-dependent beam patterns and observable signatures without assigning the model to a luminosity regime, focusing on cyclotron-resonance and polarisation effects as tracers of anisotropy. To do so, we computed angle-dependent polarised broadband spectra, including the fundamental cyclotron line, for a homogeneous, self-emitting, magnetised Comptonizing
plasma over a broad parameter range. Accounting for light bending and projection, we obtained phase-dependent fluxes for different geometries and, for hot spots, observed linear polarisation. The beam patterns evolve with energy, driving pulse-profile changes. Near the cyclotron resonance,
plasma-
vacuum interplay produces a narrow central beam and side petals. Their visibility creates geometry-dependent dips, bumps, and M- and W-shaped structures in hot-spot pulsed fraction spectra, but only dips and bumps for columns. Thermally Comptonized cyclotron lines do not reliably trace
plasma temperature;
plasma-induced ellipticity and band averaging reduce observed soft-X-ray linear polarisation to 0-30%. Under typical X-ray
pulsar accretion-channel conditions, thermal Comptonization leaves robust energy-dependent anisotropic signatures. Energy-resolved pulse profiles, pulsed fraction spectra, and polarisation thus provide complementary diagnostics of
neutron star geometry, emission-region shape, and spectral formation.
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All authors E. Sokolova-Lapa, D. K. Maniadakis, J. J. R. Stierhof, E. Ambrosi, A. D'Aì, C. Ferrigno, N. Schettino, M. Middleton, A. Gúrpide, V. Grinberg, G. Lipunova, I. El Mellah, P. Kretschmar, J. Wilms
Astrophysics of Galaxies
Interstellar Aromatic Infrared Bands: IR absorption spectroscopy of the lowest triplet state of naphthalene
Priyanka Arvind Paunikar, Hugo Maurer, Lars Reems et al. (+5 more)
The aromatic infrared bands (AIBs), emission features observed ubiquitously across a wide variety of interstellar objects, are commonly attributed to radiative cooling of highly-excited ground-state vibrational levels of polycyclic aromatic hydrocarbons (PAHs) that are populated after UV absorption and internal conversion. However, for neutral PAHs intersystem crossing to the triplet
manifold, followed by radiative cooling of vibrational levels within the lowest excited triplet state is expected to be a competing relaxation channel. This state differs in vibrational frequencies, transition moments and internal energy, and therefore gives rise to different emission spectra. Despite their significance, neutral PAHs in their triplet states have remained largely unexplored, primarily because of the lack of direct spectroscopic access. Here, we report the first measurement of the infrared absorption spectrum of the lowest triplet state of naphthalene. The spectrum is markedly different from the vibrational spectrum of the singlet electronic ground state, displaying features that can help identifying PAHs in the triplet states in astronomical spectra. We also show that experimental spectra are closely reproduced by anharmonic frequency calculations. These findings serve as a stepping stone for detecting triplet-state PAHs in the interstellar medium and provide a basis for developing more accurate infrared emission models.
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All authors Priyanka Arvind Paunikar, Hugo Maurer, Lars Reems, Alessandra Candian, Sandra Brunken, Jos Oomens, Piero Ferrari, Wybren Jan Buma
Plasma Physics
Spatio-Temporal Synchronization of Counter-Propagating Femtosecond Pulses
Tamir Cohen, Moshe Fraenkel and Ishay Pomerantz
Generating intense x-ray radiation via inverse-Compton scattering and exploring the strong-field regime of QED, require precise spatio-temporal synchronization of tightly focused counter-propagating intense
laser pulses. We present a protocol for establishing spatio-temporal synchronization in this geometry that combines microscope-based target positioning, wavefront-sensor-assisted
alignment of off-axis
parabolic mirrors, and a high-resolution temporal delay scan based on interference. We observed an interference window of 72 fs in good agreement with the expected autocorrelation width. The accuracy levels in space and time of using this protocol are discussed.
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High Energy Physics (Theory)
New RG flows between non-Unitary CFTs from exact massless scattering theories
Changrim Ahn, Zoltan Bajnok and Soma Elek
We construct complete solutions of the massless S-
matrix bootstrap equations describing a new infinite family of integrable RG flows from the higher-fusion-level minimal models M(3,2n+3;n) to the non-
unitary Virasoro minimal models M(2,2n+3), including a flow from M(3,5) to the Yang–Lee CFT M(2,5) when n=1. We provide strong evidence for this identification by matching conformal perturbation theory around the UV fixed points with the small-volume expansion of the corresponding thermodynamic Bethe ansatz equations. We further show that a family of non-invertible Verlinde defect lines is preserved along the flows.
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Statistical Mechanics
Emergence of Stigmergic Transport in Granular Environments
F.Wéry, F.N. Pinan Basualdo, B. Gorissen et al. (+1 more)
We show that stigmergic path formation emerges in a deformable environment through the interplay between environmental
memory and geometrical crowding. Using experiments with robotic random walkers together with a minimal
stochastic model, we demonstrate the onset of persistent self-reinforced transport pathways above a critical packing fraction $\phi_c$, where environmental
memory enhances walker mobility. As the jamming transition $\phi_J$ is approached, increasing crowding progressively suppresses this transport enhancement despite the persistence of environmental
memory. The resulting non-monotonic behavior reveals an optimal transport regime well below jamming. More generally, our work establishes how active
agents can collectively build transport networks through purely mechanical interactions with a deformable substrate.
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All authors F.Wéry, F.N. Pinan Basualdo, B. Gorissen, N.Vandewalle
Statistical Mechanics
Exact autoregressive sampling of planar Ising spin glasses via the Kac–Ward theory
Jing Liu, Tao Chen, Tianrui Che et al. (+3 more)
Exact sampling from the Boltzmann distribution of
spin glasses remains an outstanding challenge: Markov chain Monte Carlo methods suffer from critical slowing down and metastable trapping, while modern neural autoregressive samplers such as variational autoregressive networks are approximate and, in the absence of exact reference samples, cannot be rigorously benchmarked. Here we present an exact autoregressive sampling
algorithm for planar Ising
spin glasses based on the Kac–Ward theory. Under the chain-rule factorization, sequentially fixing
spins induces boundary-localized external fields, which destroy the zero-field structure required for exact evaluation. By encoding these fields with a planarity-preserving auxiliary
spin construction, the conditional partition functions are mapped to an extended zero-field Ising model and exactly evaluated using the Kac–Ward determinant formula. The method generates strictly independent and identically distributed samples with exact normalized likelihoods at a computational cost of $\mathcal{O}(N^{5/2})$ for $N$
spins, thereby providing an exact baseline for benchmarking neural autoregressive samplers.
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All authors Jing Liu, Tao Chen, Tianrui Che, Lei Wang, Youjin Deng, Pan Zhang
Soft Condensed Matter
Conformation-Mediated Kinetics of Polymer Chain Scission under Tension
Jie Zhu and Laurence Brassart
Chain scission is a key molecular process underlying damage and fracture in
polymer networks. In this Letter, we develop a statistical-mechanical framework for predicting chain-scission kinetics while accounting for three-dimensional (3D) conformational fluctuations. Within transition-state theory, scission is formulated as a multichannel first-rupture problem, with bond-specific rates governed primarily by self-consistent potentials of mean force. In the freely jointed limit, the additional 3D configurational freedom enhances rupture relative to the collinear 1D reference. Finite bending stiffness introduces orientational correlations that can reverse this enhancement and, at high stiffness, reduce rupture rates by orders of magnitude. These correlations also make rupture bond-position dependent, with higher rates near the chain ends and a common interior rate. For sufficiently long chains, the interior contribution dominates, yielding linear scaling of the chain-scission rate with chain length. These molecularly resolved rates provide physically grounded inputs for future network-scale models of
polymer damage and fracture.
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Quantum Physics
ABSTRACTS: Amsterdam Benchmark Suite for the Time and Resource Analysis of Clifford+T Simulators
Matthew Sutcliffe and John van de Wetering
Recent years have seen a rapid growth in literature presenting new methods for simulating non-Clifford
quantum circuits with classical hardware. These methods span a range of approaches, including stabiliser decomposition and tensor contraction techniques, varying in efficiency depending on
circuit class, depth, non-Clifford gate count, and other metrics. A notable limitation of this literature is the lack of a standardised approach to benchmarking, with each new paper outlining its own specification, simulating its own set of
circuits on the authors' own hardware. This paper seeks to address this issue by presenting a standardised and canonical
benchmark suite and infrastructure for quantifying the efficiency of non-Clifford classical simulators, with a consistent
dataset of
circuits and providing consistent (virtual) hardware, thereby enabling a fair comparison of results.
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Atomic Physics
Measurement of the O$^{-}$ Photodetachment cross-section in the electrostatic storage ring FLSR
Oliver Forstner, Thorben Niemeyer, Andrey I. Bondarev et al. (+10 more)
The achievable precision of photodetachment studies via tunable
laser light has been investigated on circulating oxygen anions at the room-temperature electrostatic low-energy storage ring of Frankfurt University (FLSR) in preparation of investigations on molecular species. For this purpose, the FLSR, originally designed for reaction dynamics studies on positive ions, was upgraded by a source for anions, by the installation of a tunable high repetition rate
laser system and by implementation of a transversal interaction region between
laser and ion beam. Results on the electron affinity and the ground state fine structure of O$^{-}$, which both serve as a calibration standard, are discussed, exhibiting the performance and accuracy of this new spectroscopic application of the FLSR.
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All authors Oliver Forstner, Thorben Niemeyer, Andrey I. Bondarev, Markus Dworak, Vadim Gadelshin, Raphael Hasse, Lothar Schmidt, Markus Schöffler, Matou Stemmler, Kurt E. Stiebing, Dominik Studer, Klaus Wendt, Patric Ziel
Materials Science
A hidden low-temperature transformation pathway in compositionally complex materials
Yujiao Li, Elaheh Akbarnejad, Quentin Bizot et al. (+9 more)
Most compositionally complex materials (CCMs, frequently referred to as high
entropy alloys) are metastable and their attractive properties often belong to kinetically trapped states. However, pathways towards lower-free-energy phase states governing long-term stability, can remain hidden because
diffusion-controlled atomic redistribution is too slow to be revealed at experimentally accessible timescales. This blind spot is acute in CCM design: enormous compositional spaces are screened for performance, yet the low-temperature kinetics and the associated transformation pathways determining whether that performance persists are rarely considered in material selection. Here we use defect-rich nanoscale volumes coupled with atom-probe
tomography to access and reconstruct the hidden phase-
evolution pathway in a metastable Ag24Au20Pd50Pt6 electrocatalyst, without relying on elevated temperatures to accelerate the transformation. By varying microstructural starting state, annealing temperature and time, we reveal precipitation of a Pt-rich phase within the fcc
matrix, its coarsening and re-homogenization. The Pt-rich phase recurs after homogenization with delayed kinetic accessibility, while prolonged annealing extends the pathway to 300{\deg}C. Atomistic simulations independently predict the same Pt-rich phase selection. The transformation is accompanied by a 3.7-fold loss of catalytic activity for hydrogen
evolution. These results establish hidden phase-
evolution pathways as a materials-design variable: resolving them can guide the selection of metastable CCMs not only for their as-synthesized properties, but also for the phase states and associated functionalities they may access over time.
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All authors Yujiao Li, Elaheh Akbarnejad, Quentin Bizot, Aleksander Kostka, Natalia Pukhareva, Ridha Zerdoumi, Alan Savan, Matous Mrovec, Ralf Drautz, Baptiste Gault, Dierk Raabe, Alfred Ludwig
Quantum Physics
Essentially optimal gate teleportation
Lukas Schmitt and David Sutter
Gate teleportation allows us to implement a nonlocal
unitary using local operations, classical communication (LOCC), and a shared entangled state. Known deterministic teleportation protocols consume at least one full ebit and achieve optimal
entanglement consumption only for Clifford gates. Here, we present a deterministic LOCC protocol for implementing the two-
qubit controlled-phase gate $U_{\phi}=\mathrm{diag}(1,1,1,e^{i \phi})$ with $\phi \in [0,\pi]$ whose
entanglement consumption is close to optimal for every $\phi$. In particular, vanishing rotation angles require vanishing
entanglement.
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Optics
Nonlocal-nonlinear phonon polaritons
Gonzalo Álvarez-Pérez, Line Jelver, Alexander Paarmann et al. (+1 more)
When light is confined to deeply subwavelength volumes, optical responses can become nonlocal. Yet how nonlocality reshapes nonlinear light-matter interactions remains largely unexplored, particularly in dielectrics. Here, we theoretically uncover a new class of nonlinear optical processes arising from the interplay between optical-
phonon propagation and ionic-bond anharmonicity in polar
crystals. We show that, unlike conventional local nonlinearities, this mechanism enables second-order responses even in centrosymmetric materials. Moreover, these responses can be tuned by the confinement and resonantly enhanced near optical-
phonon resonances. Using density functional perturbation theory, we quantify the resulting nonlocal second-order susceptibilities in representative polar
crystals. Our results establish nonlocal-nonlinear optics as a new regime of light-matter interaction in dielectrics.
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All authors Gonzalo Álvarez-Pérez, Line Jelver, Alexander Paarmann, Simone De Liberato
Instrumentation and Methods for Astrophysics
Digging dark holes on-sky with the Self-Coherent Camera: Preliminary results
Elena Tonucci, Sebastiaan Y. Haffert, Jared R. Males et al. (+17 more)
Current high-contrast imaging instruments are limited by wavefront errors originating from non-common path aberrations (NCPAs) due, for example, to manufacturing errors in the optics and temperature drifts in the system. These create quasi-static speckles in the final science image that are difficult to distinguish from companions. Therefore, focal plane wavefront sensing and control is needed to suppress speckles. The Self-Coherent Camera (SCC) is a wavefront sensor that allows us to estimate the
stellar complex speckle field. In the Fast Atmospheric SCC Technique (FAST), the on-axis starlight hits a coronagraphic focal plane phase mask and is diffracted outside the Lyot stop where it is spatially filtered by a pinhole to create a reference beam. The reference beam and the leaked starlight are recombined on the science plane, creating interference fringes that do not affect the companion, because of incoherence. The focal plane mask was manufactured in-house at Leiden University with Nanoscribe, a micro-3D-printer that uses two-
photon polymerization to achieve sub-micron precision in height. We present preliminary results of the first on-sky closed-loop SCC demonstration with the Magellan Adaptive Optics eXtreme (MagAO-X) instrument on the 6.5-meter Magellan Clay
telescope at Las Campanas Observatory, Chile. We achieve a 1-sigma raw contrast improvement of a factor 10 in the desired dark hole region with FAST closed-loop control. In the future, we will show observations of
stars with companions and use the SCC in post-processing as a Coherent Differential Imaging (CDI) technique to enhance the contrast even further.
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All authors Elena Tonucci, Sebastiaan Y. Haffert, Jared R. Males, Laird M. Close, Kyle van Gorkom, Olivier Guyon, Alexander D. Hedglen, Parker T. Johnson, Maggie Y. Kautz, Jay K. Kueny, Jialin Li, Joshua Liberman, Joseph D. Long, Jennifer Lumbres, Matthijs Mars, Eden A. McEwen, Avalon McLeod, María Eugenia Redondo González, Lauren Schatz, Katie Twitchell
Instrumentation and Methods for Astrophysics
On-sky demonstration of self-learning predictive control with MagAO-X
Sebastiaan Y. Haffert, Jared R. Males, Parker T. Johnson et al. (+13 more)
Direct imaging of
exoplanets is very tricky and requires extremely well corrected wavefronts. Especially low-order order modes are detrimental to the performance of coronagraphs at their inner-working angle. However, that is precisely where conventional AO systems have the highest residuals that are caused by servo-lag errors. This servo-lag error can be reduced with predictive control where the control anticipates the future state of the atmospheric disturbance. We use a self-learning model predictive controller based on the concepts from sub-space predictive control (SPC). We present a novel implementation of the SPC by using an online QR-decomposition based recursive least squares approach. This approach has now been used for self-learning control of vibrations on the MagAO-X instrument. We see on average an Strehl increase of 15 percent and a decrease of the jitter to 0.9 mas. I will discuss how we have implemented the controller and its on-sky perfomance.
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All authors Sebastiaan Y. Haffert, Jared R. Males, Parker T. Johnson, Laird M. Close, Olivier Guyon, Jay Kueny, Joshua Liberman, Joseph D. Long, Miles Lucas, Eden McEwen, Tiffany Nguyen, Adam K. Taras, Kyle Van Gorkom, Maggie Kautz, Katie Twitchell, Lauren Schatz
Strongly Correlated Electrons
Influence of the inter-orbital interaction and kinetic terms on superconductivity: a simple two-orbital Hubbard model
Vito Marino, Diego Florez-Ablan, Luca F. Tocchio et al. (+2 more)
We investigate a minimal two-orbital Hubbard model with intra- and inter-orbital nearest-neighbor hopping $t$ and $\tilde{t}$, as well as intra- and inter-orbital density-density interactions $U$ and $U'$ by means of variational ansätze based on Jastrow-Slater wave functions within
quantum Monte Carlo techniques. To focus on the electronic mechanisms of superconductivity, we restrict the variational ansätze to uniform nonmagnetic states with an explicit pairing amplitude and compute the pairing correlations as a function of filling and model parameters. At $U/t=10$, superconducting correlations are highly enhanced by the presence of inter-orbital terms, $U'$ and $\tilde{t}$. For $\tilde{t}=0$, a finite value of $U'$ effectively screens the intra-orbital repulsion $U$, producing a shift in the superconducting dome. Consequently, inter-orbital repulsion yields a sizable increase in electron pairing compared to the single-orbital baseline. Furthermore, introducing a finite $\tilde{t}$ provides an additional boost to superconducting correlations, an effect driven by the simultaneous presence of flat and broad bands in the electronic structure.
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All authors Vito Marino, Diego Florez-Ablan, Luca F. Tocchio, Massimo Capone, Federico Becca
Instrumentation and Methods for Astrophysics
Sub-diffraction-limited coronagraphic imaging with nano-printed PIAACMC phase masks
Elena Tonucci, Sebastiaan Y. Haffert, Warren B. Foster et al. (+22 more)
Imaging Earth-like
exoplanets in the habitable zone of their host
star is among the main science objectives of future ground-based and space-based observatories. However, the extreme contrast and small separations needed to image such
planets cannot be reached with current technology. The Phase-Induced Amplitude Apodization Complex Mask Coronagraph (PIAACMC) is a promising coronagraph to reach this goal. The PIAACMC uses a set of aspheric lenses to apodize the entrance pupil without throughput losses and a phase-shifting focal plane mask for starlight suppression. These allow us to maintain high throughput and achieve a small inner-working angle (IWA), unlocking the capability to observe
exoplanets at the diffraction limit. The masks are manufactured in-house at Leiden University with Nanoscribe, a micro-3D-printer that uses two-
photon polymerization to achieve sub-micron precision in height. We present the first scientific results with a focal plane mask for the PIAACMC on the Magellan Adaptive Optics eXtreme (MagAO-X) instrument for the 6.5-meter Magellan Clay
telescope at Las Campanas Observatory, Chile. We show laboratory and on-sky contrast curves with a broadband z' filter centered at 908 nm with a 14% bandwidth. We use the PIAACMC to detect binary companions at separations ~0.8-5 lambda/D (~23-144 mas). This demonstrates the PIAACMC's capability to observe at the diffraction limit and below, with a sub-lambda/D IWA. Future work includes exploring new mask designs to improve the contrast in broadband light and performing active focal plane wavefront sensing and control.
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All authors Elena Tonucci, Sebastiaan Y. Haffert, Warren B. Foster, Jared R. Males, Olivier Guyon, Laird M. Close, Kyle van Gorkom, Alexander D. Hedglen, Parker T. Johnson, Maggie Y. Kautz, Jay K. Kueny, Rico Landman, Jialin Li, Joshua Liberman, Joseph D. Long, Miles Lucas, Jennifer Lumbres, Matthijs Mars, Eden A. McEwen, Avalon McLeod, Tiffany Nguyen, Logan A. Pearce, María Eugenia Redondo González, Lauren Schatz, Katie Twitchell
High Energy Physics (Phenomenology)
Exclusive Determination of $|V_{cb}|$ from Semileptonic Decays $B\to D^{(*)}\ell \nu_{\ell}$
Xue-Wen Chen, Bo-Yan Cui, Jia-Wei Zhang et al. (+2 more)
We present an updated exclusive determination of the CKM
matrix element \(|V_{cb}|\) from the semileptonic decays \(B\to D^{(*)}\ell\bar{\nu}_{\ell}\). Our analysis combines the latest Belle II measurements, updated
lattice-QCD calculations of the \(B\to D^{(*)}\) form factors at small hadronic
recoil, and correlated large-
recoil SCET sum-rule predictions incorporating next-to-leading-order QCD corrections and several power-suppressed contributions. We consider three fit scenarios with progressively enlarged input sets and find that the inclusion of the large-
recoil sum-rule constraints substantially reduces the form-factor uncertainties. From the full global fit, we obtain\(|V_{cb}|=(39.18 \pm0.47)\times10^{-3}\). Using the combined
lattice-QCD and LCSR fit, we predict \(R(D)=0.3069\pm0.0080,\qquad R(D^*)=0.2548\pm0.0043\), and provide differential decay distributions in the momentum transfer and angular variables for both the
muon and tau channels. Comparisons of the individual and correlated predictions for \(R(D)\) and \(R(D^*)\) with the experimental averages reveal a persistent tension. In particular, our theoretical 68% confidence region shows little overlap with the experimental average. All correlations among the fitted parameters are retained in the uncertainty propagation. Our results therefore provide updated Standard Model
benchmarks for tests of
lepton-
flavor universality. Improved
lattice-QCD calculations, sum-rule predictions, and Belle II measurements will be essential for determining whether the remaining discrepancies originate from theoretical systematic uncertainties or from physics beyond the Standard Model.
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All authors Xue-Wen Chen, Bo-Yan Cui, Jia-Wei Zhang, Xue-Chen Zhao, Ya-Hui Chen
Plasma Physics
Anomalous Electric Fields in Earth's Turbulent Magnetosheath: Insights From 3D Hybrid Simulations
Jeffersson A. Agudelo Rueda, Julia E. Stawarz, Luca Franci et al. (+3 more)
In both collisional and collisionless
plasmas the presence of a broad range of electromagnetic and
plasma fluctuations provides anomalous electric fields that can be important for the dynamical
evolution of the system as it is the case of
magnetic reconnection,
plasma turbulence and dynamo theory. In the context of
plasma turbulence at scales larger than the ion's inertial length, the
plasma satisfies the frozen-in condition, and the anomalous electric fields are produced by correlations between turbulent velocity and
magnetic fields. Conversely, for collisionless
plasmas and at kinetic scales, the total electric field has additional contributions that arise from kinetic phenomena, namely, charge separation, ambipolar electric fields and electron inertia, and each of these terms presents an anomalous counterpart. In this work we characterize the anomalous electric fields. We present a framework that can explain partial balance between the anomalous resistivity and anomalous transport, and we use it to study anomalous electric fields at kinetic scales. We establish how the different contributions to the anomalous electric field couple to the large-scale electric fields and show that the anomalous terms act back-reacting on
magnetic-field organization and they may contribute to effective turbulent
magnetic diffusion or shielding. Finally, we test two Sub-Grid-Scale models including anisotropic transport coefficients and show that although these models partially recover the spectral information, the phase coherence is not entirely recovered by these models suggesting a more complex non-linear contribution of the anomalous terms to the resolved scales.
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All authors Jeffersson A. Agudelo Rueda, Julia E. Stawarz, Luca Franci, Nobumitsu Yokoi, Camille Granier, Silvio S. Cerri
Instrumentation and Methods for Astrophysics
The final design of GMagAO-X: the wavefront sensing and control (WFS&C) architecture of GMagAO-X
Sebastiaan Y. Haffert, Jared R. Males, Laird M. Close et al. (+10 more)
The
Giant Magellan Adaptive Optics eXtreme (GMagAO-X) instrument has now been selected as an official part of the
Giant Magellan
Telescope's (GMT) instrument suite. The instrument will be ready at first-light of the GMT in the mid 2030s. The instrument is now progressing towards its final design with a final design review planned for March, 2027. The high-density actuator deformable mirror with 21.000 actuators will allow GMagAO-X to create diffraction-limited images from visible to near-infrared. GMagAO-X will be coupled with high-performance coronagraphs to search for
exoplanets at the diffraction-limit. The coronagraphs require wavefront control at sub-nm precision. We will provide an update on the wavefront sensing and control architecture and how the loops interact with each other through end-to-end simulations.
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All authors Sebastiaan Y. Haffert, Jared R. Males, Laird M. Close, Olivier Guyon, Olivier Durney, Maggie Kautz, Liam Koning, Louis Desdoigts, Matthijs Mars, Elena Tonucci, Adam K. Taras, Yinzi Xin, Rico Landman
Fluid Dynamics
Assessment of turbulent fire dynamics and combustion instabilities using a flamelet model
Yunxiao Yan, Fabian Brännström, Christian Hasse et al. (+1 more)
The Sandia one-meter methane fire plume is an established
benchmark for turbulent combustion modeling of large-scale flames. This study investigates the combustion instabilities formed close to the base of the Sandia fire plume. Finite rate chemistry and differential
diffusion are considered using a flamelet/progress variable (FPV) approach. The performance of the FPV approach is assessed by comparing with the eddy dissipation model (EDM) and the experimental data for the large-scale fire plume via large eddy simulations (LES). The effects of radiation modeling and mesh resolution on the predictive capability of the model are systematically investigated by comparing the axial and radical velocities against the experimental data at various locations. Although all models successfully capture the primary flow characteristics of fire plumes, the FPV model with differential
diffusion yields improved predictions in the near-flame-base region. The formation mechanism of cellular flow structures near the flame base is investigated via a budget analysis of the vorticity equation, and the type of instability governing the formation of the cellular structure is clarified. Finally, the individual effects of finite rate chemistry and differential
diffusion on the prediction of the thermo-chemical quantities are quantified. Overall, this study explains the underlying physics governing combustion instabilities at the base of turbulent fire plumes, provides novel insights into the performance of flamelet models for LES of gaseous pool fires, and offers reliable guidance for the high-fidelity numerical simulation of large-scale turbulent buoyancy driven flames.
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All authors Yunxiao Yan, Fabian Brännström, Christian Hasse, Xu Wen
Superconductivity
Polireddi Naveen and Abhiram Soori
We theoretically investigate
equilibrium currents in a one-dimensional Josephson junction incorporating a bipolar
magnetic semiconductor (BMS). We show that the intrinsic exchange splitting of the
spin-resolved bands enables purely electrical control of the $0$–$\pi$ transition through gate-tunable modulation of the BMS chemical potential, eliminating the need for an external
magnetic field. This provides a viable route toward electrically tunable $\pi$-junction behavior and highlights the potential of BMS-based Josephson devices for phase-controllable superconducting electronics. Furthermore, in the presence of Rashba
spin–orbit coupling, we find an anomalous Josephson effect characterized by a finite
equilibrium supercurrent at zero phase difference. This behavior originates from the intrinsic breaking of time-reversal
symmetry associated with the
spin-polarized electronic structure of the BMS. Interestingly, despite the simultaneous breaking of time-reversal and inversion
symmetries—conditions often associated with nonreciprocal superconducting transport—we do not observe a Josephson diode effect. Our results therefore highlight an important distinction between anomalous Josephson transport and superconducting nonreciprocity: the former does not necessarily imply a finite critical-current asymmetry between opposite current directions.
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