Nuclear Theory
Local Spin Polarization in Anisotropic Gubser Flow: Suppression Mechanism and Formulation Dependence
Kenji Fukushima, Shi Pu and Dong-Lin Wang
We analytically study the longitudinal
spin polarization in relativistic heavy-ion collisions using a perturbed Gubser flow solution. In the large-system-size limit, we derive analytical expression of the local
spin polarization along the beam direction. In our treatment, the contributions from thermal vorticity and thermal shear are of comparable magnitudes. The thermal vorticity yields the polarization with a sign opposite to that observed experimentally, while the thermal shear counteracts this effect, helping recover the desired sign. We find that the choice of the reference unit vector aligned with the fluid velocity gives the experimentally observed sign only at low transverse momenta, whereas another formulation with the unit vector fixed along the laboratory time direction yields the desired sign for a wide range of transverse momenta. Notably, a recent formulation with the unit vector normal to the freeze-out hypersurface exhibits an exact cancellation between contributions from thermal vorticity and thermal shear at leading order in the large-system-size limit. We identify a general cancellation pattern with acceleration dominance, which is manifest particularly in the latter two formulations. Thus, the total polarization originates from non-acceleration effects, which need not be substantial even when the
elliptic flow is finite, as clearly demonstrated in our analytical results. For comparison, we also discuss the
spin polarization in the Hubble flow with rotation.
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Quantum Physics
Exact Tradeoff Between Quantum Error Correction and Quantum Darwinism: An Information-Theoretic No-Go Theorem
Arghya Maity, Kelvin Onggadinata and Teck Seng Koh
Quantum error correction (QEC) and
Quantum Darwinism describe opposing consequences of system-environment interactions: QEC seeks to preserve logical
quantum information, whereas
Quantum Darwinism explains the emergence of objective classical information through its proliferation into the environment. Despite their common physical origin, no direct quantitative connection between these paradigms has previously been established. We introduce an exactly solvable block-environment model based on the logical GHZ block of the Shor [[9,1,3]]
quantum error-correcting code, collectively coupled to N environment
qubits. The logical fidelity, Holevo information, and Darwinistic redundancy are obtained systematically for arbitrary environment size and imperfect recovery efficiency. Eliminating the common decoherence parameter yields an exact tradeoff relating Darwinistic redundancy directly to the post-recovery logical fidelity, demonstrating that the emergence of redundant classical records occurs at the expense of logical
quantum information. We further prove a model-independent no-go
theorem showing that the logical fidelity exceeds a critical threshold precludes the emergence of Darwinistic redundancy, irrespective of the microscopic
Hamiltonian or environment structure. The solvable model saturates this general bound, establishing the first quantitative information-theoretic connection between logical
quantum information protection and the emergence of redundant classical records.
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Nuclear Experiment
Statistical and non-statistical $\gamma$-decay properties of $^{64}$Zn
A. C. Larsen, M. Guttormsen, T. K. Eriksen et al. (+23 more)
We present a study on the $\gamma$-decay properties of $^{64}$Zn using the Oslo method on $^{64}$Zn($p,p^\prime \gamma$) data combined with $^{64}$Zn$(\gamma,n)$ cross-section measurements at the NewSUBARU facility. With the Oslo method, we have measured the $\gamma$-ray strength function ($\gamma$SF) and the
nuclear level density (NLD) below the
neutron threshold. We observe that the NLD trend in the quasi-continuum region of $^{64}$Zn is best characterized by a constant-temperature-like model. %with temperature parameter $T_{\rm CT}=1.21(5)$ MeV. Surprisingly, we find that $\gamma$-ray transitions from the quasi-continuum decaying directly to the $0^+$ ground state seem to be strongly hindered with a hindrance factor of $\kappa \approx 0.5$, which could be an indication of non-statistical effects in the ground-state decay due to, e.g., differences in
nuclear shapes. For $\gamma$ energies above the
neutron separation energy, the NewSUBARU ($\gamma, n$) data set probes a significant part of the
giant dipole resonance. Furthermore, we find that the Oslo-method $\gamma$SF shows a rather smooth behavior, with a clear low-energy enhancement (LEE) for $E_{\gamma} < 4$ MeV.
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All authors A. C. Larsen, M. Guttormsen, T. K. Eriksen, G. M. Tveten, H. Utsunomiya, J. K. Dahl, N. Shimizu, T. Ari-izumi, F. L. Bello Garrote, L. T. Bell, M. M. Bjørøen, F. W. Furmyr, D. Gjestvang, A. Görgen, V. W. Ingeberg, K. C. W. Li, E. Lima, M. Markova, E. F. Matthews, A. H. Mjøs, S. Miyamoto, V. Modamio, T. Renstrøm, E. Sahin, S. Siem, M. Wiedeking
General Relativity and Quantum Cosmology
Charged topological geons with a self-gravitating scalar field
Alexander Tsirulev
A topological geon is an asymptotically (anti-)de Sitter or flat spacetime with
topology $\mathbb{R}\times M$, where $M$ is the punctured projective space, $M=\mathbb{R}P^3\backslash\{p\}$, and the removed point $p$ corresponds to the spacelike infinity. The
manifold $M$ is conventionally obtained from a spherically symmetric spatial slice of a wormhole spacetime as the quotient
manifold by the isometric action of the group $\mathbb{Z}_2$. We study the general properties of static, spherically symmetric, charged topological geons supported by a selfgravitating, minimally coupled scalar field with negative kinetic energy and an arbitrary selfinteraction potential. In the most general case, it turns out that the gravitational mass of such a geon is completely determined by its electric charge and size (for a given scalar field), that is, the size of the corresponding wormhole throat. We discuss the properties of the charged Ellis-Bronnikov-Sorkin geon and argue that it can be considered as a possible classical model of elementary particles beyond the Standard Model, in particular, as dark matter particles.
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Atomic Physics
Enhanced coherence of rare-earth nuclear spins in a crystal
Bassam Nima, Yuiki Takahashi and Amar Vutha
Rare-earth ions in
crystals are useful in precision measurements and
quantum information science because of their exceptional optical and
spin coherence properties. We show that the
nuclear spin coherence time of $^{153}\mathrm{Eu}^{3+}$ ions doped into yttrium orthosilicate can be significantly enhanced by driving the environmental
nuclear spins in the host
crystal. This method of enhancing the
spin coherence time can lead to improved precision measurements using rare-earth-doped
crystals.
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High Energy Physics (Phenomenology)
Di-Higgs Production and Trilinear Higgs Self-Coupling in the scNMSSM: Qualitative Implications for the Electroweak Phase Transition at large {\lambda} and Low tane̱ta}
Marwa Telba
The trilinear
Higgs self-coupling and di-
Higgs production cross section are investigated in the semi-constrained NMSSM (scNMSSM) at large-$\lambda$ / low-$\tan\beta$ with full two-loop precision. A random scan of one million parameter points subject to theoretical,
collider,
flavor, and dark matter constraints yields 66 SM-like points with singlet fraction $S_{13}^2 < 0.05$, all found in the mass range $m_{h_1} \in [122.0,\,125.0]~\text{GeV}$ — a feature that reflects an intrinsic property of the scNMSSM at large-$\lambda$ / low-$\tan\beta$, where doublet-dominated configurations are kinematically confined below ${\sim}125~\text{GeV}$. The trilinear coupling ratio is found to be universally suppressed: $\kappa_\lambda = 0.884$–$0.982$, $\langle\kappa_\lambda\rangle = 0.944 \pm 0.018$. The non-resonant di-
Higgs cross section at $\sqrt{s} = 13.6~\text{TeV}$ lies in the range $30.3$–$36.9~\text{fb}$ ($0.88$–$1.05\,\sigma_{\rm SM}$), with the resonant contribution via $gg \to h_3 \to h_1h_1$ negligible ($\leq 0.004~\text{fb}$). All predictions are consistent with current ATLAS+CMS di-
Higgs upper limits and is expected to be probed at the HL-LHC. These results are discussed in the context of the electroweak phase transition, where the universal suppression of $\kappa_\lambda$ is qualitatively consistent with a modified
Higgs potential that could support a strengthened first-order transition. A quantitative determination of the phase transition strength via finite-temperature analysis is left for future work.
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Materials Science
Understanding and Designing Phase Change Materials: Insights from Atom Probe Tomography
Jan Köttgen, Nils von den Driesch, Alexander Pawlis et al. (+1 more)
Phase Change Materials (PCMs) can be rapidly and reversibly switched between their amorphous and crystalline state; a transition which is accompanied by a pronounced change of optoelectronic properties. Here progress is reviewed to explain these property changes, focusing on advances by atom probe
tomography (APT). This technique classifies bonding by providing two crucial bonding descriptors. Most important is the Probability of Multiple Events (PME), which is related to the likelihood that more than one ion is dislodged per successful
laser pulse in
laser assisted field evaporation. Crystalline PCMs are characterized by a PME above 55%, not found for metals or iono-covalent solids. This confirms that crystalline PCMs employ a unique bonding mechanism coined metavalent bonding (MVB). While crystalline PCMs employ MVB, amorphous PCMs behave as covalent solids characterized by a much lower PME. PCMs thus change their bonding upon crystallization, consistent with
quantum-chemical calculations of bonding. Crystalline solids with a high PME lie in a narrow conductivity range between metals and iono-covalent solids, indicative for a competition between electron localization and delocalization. A map quantifying chemical bonding locates metavalent solids in a region where approximately one electron is shared between adjacent atoms and bonding is not too ionic. This
quantum chemical bonding map is now used to find and explain property trends relevant for PCMs in various application domains.
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All authors Jan Köttgen, Nils von den Driesch, Alexander Pawlis, Matthias Wuttig
High Energy Astrophysical Phenomena
First fast radio burst search campaign at the Argentine Institute of Radio Astronomy
Carlos O. Lousto, Harsh Prajapati, Ezequiel Zubieta et al. (+7 more)
Fast
radio bursts (FRBs) are intense millisecond-duration
radio transients of extragalactic origin whose physical nature remains under active investigation, and which also serve as probes of the intergalactic medium. We report on the first FRB search campaign carried out at the Argentine Institute of
Radio Astronomy (IAR) between December 2024 and March 2026, targeting nearby
galaxy superclusters in the southern sky. We observed fields in the Ophiuchus, Shapley, and Sculptor/Phoenix supercluster regions with one of the two 30~m
antennas of the IAR, using a ROACH-based backend with 400~MHz of bandwidth centred at 1400~MHz and a time resolution of 41–82~$\mu$s, for a total net observing time of 212~h. The data were searched for dispersed single pulses with PRESTO in the dispersion measure range $100 \leq \mathrm{DM} \leq 500$, and candidates were classified with the FETCH machine learning classifier. The pipeline was validated on archival Parkes data containing known FRBs and on synthetic bursts injected into IAR observations. One FRB candidate, FRB~20251018, was identified on 18 October 2025 in an observation pointed towards the
galaxy cluster A2870, in the Phoenix supercluster, with a dispersion measure of $243$, a signal-to-noise ratio of 8.2, and a FETCH probability of $p=0.99$. To the best of our knowledge, this would be the first FRB detected from South America. A set of more marginal candidates is also presented. These results demonstrate the capability of the IAR
antennas to detect FRBs and support the continuation and extension of the monitoring campaign, including coincident dual-
antenna observations and cross-matches with gravitational-wave events and electromagnetic transients.
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All authors Carlos O. Lousto, Harsh Prajapati, Ezequiel Zubieta, Susana B. Araujo Furlan, Guillermo Gancio, Joaquín Pelle, Gustavo E. Romero, Federico García, Santiago del Palacio, Nathan Cahill
Superconductivity
Thermodynamic phase transition, pairing symmetry and Fermi surface topology in Ruddlesden-Popper nickelate films
Yu Miao, Zhiwei Wang, Hongxu Sun et al. (+9 more)
Ruddlesden-Popper (RP) nickelates provide an uncharted territory to explore high-transition-temperature (high-$T_C$) superconductivity and superconducting mechanism. Here, we investigate the electronic structure of a new type of high-$T_C$ superconducting RP nickelate
heterostructure $\mathrm{La_2PrNi_2O_7/NdAlO_3}$ by angle-resolved photoemission spectroscopy. A superconducting state is observed without a pseudogap state, enabling a direct measurement of the superconducting order parameter and a microscopic extraction of the electronic specific heat. The observed superconducting gap opens at $T_C$ with prominent coherence peaks, illustrating the emergence of nonzero order parameter upon entering the superconducting state. An electronic specific heat jump appears at $T_C$, further demonstrating a thermodynamic phase transition. The magnitude of the superconducting order parameter is quantified by the observed superconducting coherence peaks, and a nodeless behavior is unambiguously established in the absence of pseudogap. The underlying
Fermi surface consists of $\alpha$, $\beta$ and $\gamma$ pockets, exhibiting a multi-orbital nature. Strain dependent measurements further reveal the $\gamma$ pocket in all superconducting and non-superconducting films with different epitaxial strain. Our results establish the missing thermodynamic evidence for superconducting phase transition in nickelates. They also provide direct evidence for the
symmetry of the superconducting order parameter and illustrate the relationship between
Fermi surface
topology and the emergence of superconductivity in RP nickelate films.
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All authors Yu Miao, Zhiwei Wang, Hongxu Sun, Jianchang Shen, Runqing Luan, Zhipeng Ou, Xinru Yong, Zhenyu Wang, Tao Wu, Haoyu Hu, Junfeng He, Xianhui Chen
Chemical Physics
A variational hybrid continuous-variable discrete-variable quantum algorithm for adiabatic nuclear dynamics
Rami Gherib, Roya Radgohar, Anastasiia Pusenkova et al. (+5 more)
Gaussian wavepacket (GWP) methods are prevalent means of solving the
nuclear time-dependent Schrodinger equation (TDSE) on classical computers. They consist of representing the
nuclear wave function as a superposition of Gaussians. Here, we present a variational hybrid continuous-variable discrete-variable (CV-DV)
algorithm for simulating adiabatic
nuclear dynamics on
qubit-oscillator
quantum hardware. It encodes a superposition of frozen Gaussians (FGs) onto the
qubit-oscillator register and evolves it according to the time-dependent variational principle (VP). We test two variants of the approach, one that evolves a single FG and another that evolves a superposition of FGs, on a set of prototypical 1D harmonic and anharmonic systems. We simulate the photoexcited state dynamics of SO2 using the single FG variant of the
algorithm and compute its autocorrelation function on physical
quantum hardware. For harmonic and Morse potentials, the variant evolving the superposition of FGs converges to the numerically exact solution as the number of Gaussians increases. In the case of the double-well potential, the
algorithm simulates wavepacket bifurcation and recurrence correctly, and the ensuing irregular dynamics moderately well. Overall, this work establishes a pathway for simulating molecular dynamics on noisy intermediate-scale
quantum devices.
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All authors Rami Gherib, Roya Radgohar, Anastasiia Pusenkova, Seyyed Mehdi Hosseini Jenab, Sara Turcotte, Dany Lachance-Quirion, Nicholas E. Frattini, Scott N. Genin
Soft Condensed Matter
Reaction Delays Boost, Rectify, and Reverse Motility in Activity Landscapes
Constantin Rein, Klaus Kroy and Viktor Holubec
Local detailed balance restricts transport by self-propulsion in static activity landscapes. We show that a delayed speed adaptation (“delayed motility/kinesis”) generically breaks this symme try, inducing directed transport in asymmetric periodic motility profiles and enhancing
diffusion in symmetric ones. Both effects occur for run-and-tumble, active Brownian, and inertial active particles, without requiring potential interactions, walls, imposed gradients, higher dimensions, or translational
diffusion. Their magnitudes, and even current reversals, are conveniently tuned via the delay time, which establishes delayed motility as a versatile generic and experimentally accessible mechanism for autonomous self-steering and transport control in motile-active-matter circuity.
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Materials Science
Phonon-based determination of elastic coefficients in the Weyl semimetal TaAs
Fabián Jofré-Parra, Debankita Ghosh and Enrique Muñoz
Reliable determination of elastic properties in topological semimetals is essential for understanding strain-related effects, but is often hindered by methodological and computational limitations. In this work, we combine first-principles
phonon calculations with an elastic continuum model to determine the elastic properties of Weyl semimetal TaAs. The sound velocities extracted from the acoustic
phonon branches are used to obtain the full set of elastic
moduli, which show good agreement with previously reported values in the literature. From these results, we derive standard elastic parameters such as bulk, shear, and Young's
moduli, and the Poisson ratio. This approach highlights a computationally efficient alternative to conventional strain-based methods, avoiding the need for large supercells when shear is applied, and thus possible strain-induced inconsistencies in the electronic basis, while providing a possibility to connect with experimental characterizations (e.g. Raman or Brillouin-Mandelstam scattering) of the
lattice dynamics in Weyl semimetals.
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Materials Science
Optical centers in cubic boron nitride and diamond: remarkable similarities
Konstantin Iakoubovskii, Andrey Katrusha, Weihua Peng et al. (+1 more)
We present a comparative study of optical absorption and luminescence from cubic boron nitride (cBN) and diamond grown by the high-pressure high-temperature technique in the same cubic press. We note remarkable similarities in spectral and spatial dependences for these two materials. Using the previous identification of defects in diamond, we tentatively assign the optical center responsible for yellow color in some cBN
crystals to substitutional oxygen at the nitrogen site, the RC1 and RC3 centers to a defect comprising substitutional oxygen and a boron vacancy in the neutral and negative charge states, respectively, the GC1 center to a nickel-related defect, the 1.816 eV (683 nm) luminescence peak to a Si-vacancy complex, and the BN1 center to an interstitial-related defect.
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All authors Konstantin Iakoubovskii, Andrey Katrusha, Weihua Peng, Jianguo Peng
Strongly Correlated Electrons
Accelerated quantum Monte Carlo simulations of the attractive Hubbard model on the kagome lattice
Jie Zhang, Xiang Li and Yu Wang
The recent discovery of several families of kagome materials and experimental realization of optical kagome
lattices have stimulated growing numerical studies of interaction-driven correlated states on the kagome
lattice. Among the available numerical approaches, determinant
quantum Monte Carlo (DQMC) is a powerful method for investigating such strongly correlated states. However, the accessible system sizes of existing DQMC simulations remain limited, preventing reliable finite-size scaling analyses. Here we develop a general acceleration scheme based on fast
Fourier transform (FFT) for propagator multiplications on composite
lattices and combine it with the delay-update
algorithm, enabling simulations on system sizes twice as large as those of previous DQMC studies, allowing reliable finite-size scaling analyses of the attractive kagome-
lattice Hubbard model. Our large-scale simulations reveal the interaction-driven zero-temperature superfluid
quantum criticality at the Dirac filling and provide reliable estimates of the associated critical exponents. Besides, we find no evidence that the previously proposed triangle-rule charge-density-wave order survives in the thermodynamic limit, suggesting that it is likely a finite-size effect. Moreover, for system sizes accessible in current two-dimensional optical
lattice experiments, the combined FFT and delay-update scheme exhibits an effective computational cost scaling as $N^{2.49}$, substantially below the $\mathcal{O}(N^3)$ computational cost of conventional DQMC simulations.
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High Energy Physics (Experiment)
Timing-Based Search for Magnetic Monopoles with the NOvA Detector on the Surface
NOvA Collaboration
We report a search for a
magnetic monopole component of the
cosmic-ray flux in a 2743-live-day exposure of the NOvA experiment's Far Detector, a 14 kt segmented
liquid scintillator detector designed primarily to observe GeV-scale electron
neutrinos. No events consistent with monopoles were observed, setting an upper limit on the flux of $8\times 10^{-16}~\mathrm{cm^{-2}s^{-1}sr^{-1}}$ at 90% C.L. for monopole speed $6\times 10^{-4} < \beta < 5\times 10^{-3}$ and mass greater than $10^{9}$ GeV. Because of NOvA's small overburden of 3 meters-water equivalent, this constraint covers a previously unexplored low-mass region.
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Chemical Physics
High-Order Response Functions with Duschinsky Coupling and Finite Temperature: Application to Two-Dimensional Resonance Raman Spectroscopy
Luca Nils Philipp and Tomislav Begušić
In this work, we derive closed-form expressions for multi-time correlation functions underlying higher-order nonlinear spectroscopic response functions within the harmonic approximation. Our method includes displacements, frequency changes, and Duschinsky rotation between the vibrational modes of different electronic states while retaining
polynomial scaling with the number of degrees of freedom. Finite temperature is accounted for without summation over vibrational eigenstates. To show the capabilities of our method, we apply it to calculate fifth-order two-dimensional resonance Raman (2DRR) spectra of two-mode model systems and naphthalene. Comparison with the displaced harmonic oscillator model shows that Duschinsky rotation modifies the positions and relative intensities of diagonal and cross peaks. Overall, our results demonstrate that 2DRR spectroscopy is particularly sensitive to changes in normal coordinates between electronic states and can provide distinct signatures of Duschinsky coupling in molecular systems.
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Cosmology and Nongalactic Astrophysics
Fisher Forecasting for the DESC with $\texttt{Augur}$
Paul Rogozenski, Sankarshana Srinivasan, Javier Sánchez et al. (+15 more)
The Vera C. Rubin Observatory Legacy Survey of Space and Time (LSST) has begun its ten-year survey of the entire visible southern hemisphere. To ensure robust cosmological measurements, computationally inexpensive investigations of modeling choices must be made to gauge the performance of proposed cosmological analyses. In this paper, we introduce the $\texttt{Augur}$ tool of the Dark Energy Science Collaboration (DESC), which provides Fisher forecasts for cosmological inference for the LSST using software frameworks designed for DESC science. We test the pipeline by comparing it to forecasts produced by external code and direct sampling of the posterior via nested sampling methods, finding good agreement between all methods. We additionally investigate a range of modeling and hyperparameter choices for a 3$\times$2pt investigation in harmonic space, providing users with diagnostics to obtain reliable forecasts. $\texttt{Augur}$ will be continually updated to be compatible with the other tools in the DESC software ecosystem as additional probes and functionality become available.
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All authors Paul Rogozenski, Sankarshana Srinivasan, Javier Sánchez, Nora Elisa Chisari, Arthur Loureiro, Marc Paterno, Rebekah Polen, Heather Prince, Biancamaria Sersante, Anže Slosar, Sandro Vitenti, Carlos García-García, Eric Gawiser, Christos Georgiou, C. Danielle Leonard, Ayan Mitra, Jeremy Neveu, The LSST Dark Energy Science Collaboration
Quantum Physics
High-level quantum structured programs as quantum registers compositions
David Chamizo, Jose Garcia-Alonso and Juan M. Murillo
Current
quantum programs are mainly designed at the level of
quantum gates acting on individual
qubits; on a large scale and for complex problems this may involve a high cognitive load on the programmer, making the program specification nontrivial and error-prone. In this context, providing
quantum programming with higher abstraction mechanisms will assist in making this task more manageable and robust against design errors. In this work, a conceptual framework is addressed following the notion of the whole
quantum computation as a structure composed of
quantum registers representing each an undivided entity. Thus, computation progresses through semantically well-defined transformations that act on, or entangle,
quantum registers, thereby modifying the global state. Ultimately, the program reaches the desired state by following a specific composition strategy. With this in mind, high-level syntax is presented through an algebraic formalism that bridges them with their low-level semantics. Proposed syntax is based on certain well-know operations used on
quantum algorithms that apply phase shifts upon logical condition satisfaction or leverage on parallel evaluation. Based solely on the formalized operations, a
quantum satisfiability modulo theories (SMT) solver can be designed. At its core, this work contributes to establishing some methodological principles towards realizing a high-level
quantum structured programming.
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Quantum Physics
Few-photon degenerate parametric resonance in a two-tone driven microwave resonator
Orjan Ameye, Jakob Koenig, Clinton Potts et al. (+2 more)
Multi-tone external driving offers a route to parametric physics without directly modulating the device. However, the validity of the parametric response in the few-
photon regime remains underexplored. Here, we apply two coherent microwave tones to a Josephson-junction Kerr oscillator and stimulate degenerate parametric downconversion via four-wave mixing. Using transmission spectroscopy, we observe that the response retains the qualitative semiclassical Kerr parametric oscillator structure, including its instability lobe and bistable phase-space
topology. Interestingly, we demonstrate that a conventional single-mode reduction fails to capture the system quantitatively: the predicted AC Stark shift is severely underestimated, and the reported distributions might not be fully physical when the single-
photon Kerr shift $K$ exceeds the cavity linewidth $\kappa$. Instead, we show that a full three-tone
quantum description accurately reproduces the experimental observables. There,
quantum fluctuations of the drive tones become dynamically dominant over dissipation, and all three interacting tones operate in a deep few-
photon limit where the expected semiclassical macroscopic lobes undergo fundamental renormalization due to profound mixing with
quantum variance. Our results establish two-tone-driven Kerr oscillators as potential parametric amplifiers and open new horizons to explore the
quantum-to-classical crossover in driven-dissipative
circuits.
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All authors Orjan Ameye, Jakob Koenig, Clinton Potts, Oded Zilberberg, Gary Steele
Mesoscale and Nanoscale Physics
Surface-Selective Probe of Spin-Triplet Superconductivity in Rhombohedral Graphene
Kilian Krötzsch, Zekang Zhou, Kryštof Kolář et al. (+6 more)
Superconductivity in rhombohedral
graphene has been observed across many layer numbers, with mounting evidence pointing toward
spin-triplet pairing, yet complementary probes of the superconducting
spin structure remain needed. Here we use one-sided WS$_2$ proximity in rhombohedral pentalayer
graphene (R5G) as a surface-selective
spin-orbit probe. The induced Ising
spin-orbit coupling is strongest for carriers localized near the WS$_2$ interface, allowing the displacement field to tune the overlap between superconducting carriers and the
spin-orbit perturbation. We observe a strongly asymmetric superconducting landscape: two robust pockets, SC1 and SC2, survive only on mutually opposite signs of displacement field, while a third pocket, SC3, is substantially weaker. Gate-tracking features,
quantum oscillations, and self-consistent band-structure calculations identify the layer polarization and
Fermi-surface character of the relevant carriers. The robust superconducting states are absent or strongly weakened when the active high-DOS carriers are polarized toward the WS$_2$ interface. Since Ising
spin-orbit coupling is compatible with time-reversed
spin-singlet pairing but competes with same-
spin intervalley triplet pairing by canting or pinning the parent
spin texture, this surface-selective suppression provides additional evidence for
spin-triplet superconductivity involving both hole-like and electron-like carriers. Our results establish one-sided TMD proximity as a displacement-field-tunable probe of superconducting
spin structure in rhombohedral
graphene.
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All authors Kilian Krötzsch, Zekang Zhou, Kryštof Kolář, Yonggen Li, Kenji Watanabe, Takashi Taniguchi, Moty Heiblum, Cyprian Lewandowski, Mitali Banerjee
Quantum Physics
Maximally Sliced States as a Framework for Quantum Coherence, Entanglement, and Teleportation under Decoherence
Anushree Pandey and Sovik Roy
Quantum resources such as coherence and
entanglement need not exhibit the same dependence on the parameters of a
quantum state, and their responses to decoherence can differ qualitatively. We investigate these relationships using the three-
qubit maximally sliced (MS) state, whose continuous parameter provides a tunable framework for redistributing
quantum correlations. We analyze the relative
entropy of coherence, (l_1)-norm coherence, and basis-independent coherence of the tripartite MS state and compare their behavior with the three-tangle. We then trace out one
qubit and study the coherence, concurrence, and optimal teleportation fidelity of the resulting bipartite state. For this reduced state, the concurrence coincides with the (l_1)-norm coherence because both are determined by the same off-diagonal
matrix element. We further examine the effects of amplitude damping and dephasing. Amplitude damping changes both populations and coherence, whereas dephasing preserves populations while suppressing phase coherence. The three coherence measures respond differently to these channels, showing that no single coherence measure fully characterizes decoherence. Under dephasing, the concurrence remains directly related to the (l_1)-norm coherence, yielding the teleportation-fidelity relation (f^T=(2+C)/3). Our results demonstrate that the MS family provides a useful tunable setting for distinguishing basis-dependent and basis-independent coherence and for studying the different responses of
entanglement and teleportation resources to dissipative and phase-decoherence processes.
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High Energy Physics (Theory)
Vacuum Polarization Energy of a Nonzero Radius Cosmic String Induced Spacetime
Noah Graham and Herbert Weigel
We calculate the
vacuum polarization energy (VPE) of a scalar field in the background of a nonsingular
cosmic string in $2+1$ spacetime dimensions. Our calculation expresses the VPE as a renormalized sum and integral over scattering data, which can be expressed in terms of Legendre and Bessel functions for the "ballpoint pen" model, analogous to a square well in
curvature, and which can be obtained numerically for a generic string profile. We show how relationships between the local density of states, expressed in terms of the Green's function, and the global density of states, expressed in terms of the Jost function, extend to this curved spacetime background and allow for precise implementation of perturbative renormalization conditions.
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Quantum Physics
Geometric-Symmetry Logical Gate and Local-Probe Selectivity in the Three-Leg AKLT Ladder
Jingnuo Han and Youning Li
Symmetry-protected topological (SPT) phases provide a platform for encoding
quantum information in protected boundary degrees of freedom. Here we study the three-leg Affleck-Kennedy-Lieb-Tasaki (AKLT) ladder as an exactly solvable SPT system with on-site
symmetry $SO(3)\times \mathbb{Z}_2$. Using an exact
matrix product state construction, we characterize the
symmetry action on the edge encoding space and the accessibility of this space by local operators. We find that the continuous $SO(3)$
symmetry induces boundary rotations, while the leg-exchange
symmetry generates a geometry-dependent logical permutation of edge
qubits. Furthermore, by introducing a distinguishability measure motivated by the Knill–Laflamme condition, we derive a
symmetry-resolved decay law for local accessibility. The decay is controlled by a selection rule raised from the Wigner–Eckart
theorem, whereby a rank-$\ell$ local operator couples only to the $\mathcal L=\ell$ transfer-
matrix sector, with a decay length determined by the corresponding correlation length. We further identify a finite-size channel that is independent of the probe operator position. These results establish a quantitative connection between SPT
symmetry,
lattice geometry, and the protection of boundary-encoded
quantum information.
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High Energy Astrophysical Phenomena
Probing Axion Like Particle-Proton Interactions through the Interplay of Dark Matter and Cosmic Rays in Large-Scale Structure
Wen-Qing Guo
Axion-like particles (ALPs) provide a well-motivated dark matter candidate whose interactions with Standard Model particles may generate observable cosmological signatures. We investigate the diffuse $\gamma$-ray emission produced by the scattering process between ALP dark matter and
cosmic-ray (CR)
protons inside dark matter
halos, and explore its detectability through the cross-correlation between the unresolved $\gamma$-ray background (UGRB) measured by
Fermi Large Area
Telescope (LAT) and the Two Micron All Sky Survey
Redshift Survey (2MRS)
galaxy catalog in the local Universe ($z\leq0.1$). To model the cosmological $\mathrm{GeV}$-$\mathrm{PeV}$ CR
proton population, we develop a phenomenological bottom-up prescription that links CR injection to the
star formation rate through the
supernova rate, while the steady-state CR density is determined by diffusive escape. Our forecasts indicate that UGRB-
galaxy cross-correlation measurements can probe previously unexplored regions of the ALP parameter space over a broad range of ALP masses. More generally, this work presents a general framework for cosmological observables generated by interactions between dark matter and an additional astrophysical field, opening a new avenue for indirect dark matter searches using large-scale structure observations.
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Earth and Planetary Astrophysics
A broad exploration of climate and observability of close-in rocky exoplanets: applications to Ross 128 b
Mathilde Houelle, Emeline Bolmont, Christophe Lovis et al. (+4 more)
VLT/RISTRETTO, ELT/ANDES and ELT/PCS will soon enable atmospheric characterization of non-transiting, small rocky
exoplanets orbiting closer than the inner edge of the Habitable Zone around M
dwarfs, combining high-contrast imaging with high-resolution spectroscopy in reflected light. A key parameter for reflected-light observability is wavelength-dependent reflectivity, shaped by
climate, surface and atmospheric properties. This work refines spectral reflectivity predictions for this population. Using Ross 128 b as a prototype, we provide physically consistent
geometric albedo estimates within the RISTRETTO and ANDES spectral ranges across diverse atmospheric scenarios. We run 3D global
climate model simulations of Ross 128 b for varying atmospheric compositions, surface pressures, water inventories and
spin-orbit resonances to explore its possible
climate regimes. We then compute synthetic reflectance spectra with Pytmosph3R to assess spectral signatures per scenario and discuss detectability and instrument capacity for constraining
climate. Results show hazeless rocky
planets receiving irradiation similar to Ross 128 b exhibit low reflectivity, with
geometric albedos of 0.07-0.2 in the RISTRETTO bandpass and 0-0.14 in the ANDES bandpass across all scenarios. This low reflectivity can stem from the lack of clouds or surface ice deposits on the dayside, or from strong atmospheric absorption due to high water vapor concentrations, depending on the parameter configurations. These features are characteristic of the
climate moist bistability found in close-in, low-water-reservoir
planets in previous studies. Our results suggest arbitrary albedo assumptions, such as the common 0.3 Earth-like value, can overestimate reflectivity for this population, highlighting the need for accurate
climate models to improve reflectivity predictions and optimize preparation for next-generation spectrographs.
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All authors Mathilde Houelle, Emeline Bolmont, Christophe Lovis, Martin Turbet, Guillaume Chaverot, Alexandre Mechineau, Jérémy Leconte
Mesoscale and Nanoscale Physics
Magnetic-field control of Fermi polaron fine structure and polarization in strained monolayer semiconductors
Zakhar A. Iakovlev
The theory of attractive
Fermi polaron energy spectrum fine structure and polarization in doped two-dimensional
semiconductors in external
magnetic field is developed.
Fermi polaron $g$ factor renormalization due to correlations with the valley-polarized
Fermi sea of resident charge carriers is calculated. We study the competition between Zeeman and strain-induced splittings in monolayers under uniaxial strain. The control of strain,
magnetic field and electron density allows continuous tuning of energy splitting and eigenstate polarization. Linearly polarized strain-induced split doublet exhibits quadratic Zeeman shift changing to linear Zeeman splitting with elliptical polarization with the increase of
magnetic field. We identify a critical
magnetic field above which resident charge carriers become fully valley polarized and only one circularly polarized
Fermi polaron state remains. Within the Green's function approach we calculate energy levels and Stokes parameters of attractive
Fermi polaron states and introduce a simplified effective two-level model allowing us to study analytically the interplay of Zeeman and pseudo-Zeeman splitting. We calculate absorption and reflection spectra, including circular and linear dichroism in the trion spectral range. These results show that real and strain-induced pseudomagnetic fields provide complementary tools for controlling the optical response of many-body excitonic quasiparticles in two-dimensional
semiconductors.
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Strongly Correlated Electrons
Local magnetic order in vacancy-disrupted spin ice Ho2TiO5
Raju Baral, Haidong Zhou, Qiang Zhang et al. (+2 more)
We investigate how local
magnetic correlations evolve when the classical pyrochlore
spin-ice Ho2Ti2O7 is transformed into the partially disordered stuffed compound Ho2TiO5.
Neutron scattering measurements were analyzed using real-space
magnetic pair distribution function, reciprocal-space reverse Monte Carlo, and half-polarized
neutron powder diffraction methods to connect the average
crystal structure with local
magnetic correlations. Both compounds retain long-range $Fd-3m
symmetry, but in Ho2TiO5 this average structure distorts locally through Ho-O, Ti-O and O-O bond-length disorder associated with partial Ho/Ti occupancy. Despite this disorder, half-polarized
neutron powder diffraction shows that the Ho moments retain local <111> rangle Ising anisotropy and form
spin-in/
spin-out configurations on the tetrahedral network. In Ho2Ti2O7, real- and reciprocal-space analyses reveal a nearly ideal two-in/two-out
spin-ice state at 0.3K, with 95% of tetrahedra satisfying the ice rule, followed by progressive thermal disordering on warming. In Ho2TiO5, most tetrahedra are magnetically incomplete because some tetrahedral vertices are occupied by nonmagnetic Ti rather than Ho; nevertheless, the dominant incomplete configurations are 2-in/1-out and 1-in/2-out, which are locally compatible with the ice rule if the missing Ho
spin is restored. The single-ion <111> Ising anisotropy is therefore retained throughout, while the collective ice ordering is strongly disrupted: Ho2TiO5 is a vacancy-disrupted
spin ice in which a local ice-rule tendency persists on a topologically incomplete
magnetic network.
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All authors Raju Baral, Haidong Zhou, Qiang Zhang, Benjamin A. Frandsen, Stuart Calder
Earth and Planetary Astrophysics
Formation of nitriles and isonitriles by the heavy-ion irradiation of propionitrile in N2-rich astrophysical ices
Ana L.F. de Barros, David Dubois, Sreeja Raghunandanan et al. (+4 more)
Context. Nitriles are key nitrogen-bearing organic molecules in dense clouds,
star-forming regions, and nitrogen-rich icy environments. Understanding their stability and chemical
evolution under energetic processing is essential for understanding the formation of complex organic species in astrophysical ices. Aims. We investigate the radiolytic processing of propionitrile (CH3CH2CN, hereafter referred to as PCN) in a nitrogen-rich ice
matrix and evaluate the formation of nitriles, isonitriles, hydrocarbons, and other nitrogen-bearing products induced by swift heavy ions. Methods. A PCN:N2 ice mixture with an approximate molecular ratio of 1:10 was deposited at 10 K and irradiated with 40 MeV 40Ar9+ ions up to a fluence of 1 x 1013 ions cm-2. The chemical
evolution was monitored in situ by
Fourier-transform infrared spectroscopy. Destruction and formation cross sections, as well as radiation chemical yields, were derived from the fluence dependence of selected infrared bands. Results. Ion irradiation efficiently destroys PCN and produces a rich inventory of daughter species. The products include: nitriles and isonitriles such as HCN, HCNN, HC3N, CH3CN, CH3C3N, CH3CHCNH, CH2CHCN, NCCN/C2N2, CN, and C2N; nitrogen-bearing species such as CH2NH, CH3NH2, CH3N3, and N3- ; and hydrocarbons, including CH4, C2H2, C2H4, C2H6, and C4H4. The derived cross sections indicate that CN-bearing fragments and hydrocarbons are among the most efficiently formed products, demonstrating that the CN group is efficiently preserved and that extensive carbon-chain reorganization also occurs. Conclusions. The results demonstrate that the energetic processing of PCN in N2-rich ices provides an efficient pathway to molecular complexity under conditions relevant to dense interstellar clouds, protostellar environments, and nitrogen-rich outer
Solar System surfaces.
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All authors Ana L.F. de Barros, David Dubois, Sreeja Raghunandanan, Thibault Nguyen Trung, Tarek Sbera, Hermann Rothard, Alicja Domaracka
Plasma Physics
Synthetic Diagnostic Modeling for Plasma Tomography: Geometry Matrix Computation Methods and Impact of Model Accuracy
D. Hamm, G. Partesotti, C. Theiler et al. (+1 more)
Tomographic emissivity reconstruction from
plasma diagnostics data relies on a synthetic model mapping the
plasma emissivity to the measured signals. The model, referred to as a geometry
matrix in the
plasma imaging community, is often built using the line-of-sight (LoS) approximation. This approximation neglects the finite width of the detector viewing beams and can therefore introduce systematic errors. Physically correct volume-of-sight (VoS) models remove this inaccuracy by accounting for the full 3D extent of the viewing beams. Their adoption, however, is sometimes hindered by the difficulty of independently validating them. We present an intuitive and easily inspectable voxel-to-detector (V2D) approach for computing physically accurate VoS geometry
matrices, based on discretizing the tokamak vessel into voxels and estimating the contribution of each voxel to the measurements of each detector. We apply the V2D approach to the soft X-ray (SXR) and bolometry systems of the TCV tokamak. Through phantom-based studies on physically realistic emissivity profiles, we quantify the improvement in reconstruction quality obtained by using VoS rather than LoS models. We find that the VoS model yields overall better accuracy and precision; however, interestingly, the simpler LoS model does not introduce a significant systematic bias in the estimated total, core, divertor and main chamber radiated powers. We further compare the V2D geometry
matrix with an independent ray-tracing implementation, finding excellent agreement that validates both approaches for routine use at TCV. All routines developed in this work are made openly available.
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All authors D. Hamm, G. Partesotti, C. Theiler, U. Sheikh
Mesoscale and Nanoscale Physics
Wavelength-Selective control of Atomic Scale Au Contacts
Werner Brämer-Escamilla, Floralba Lopez, Laila Procel et al. (+3 more)
We demonstrate wavelength-selective control of atomic motion in a mechanically controllable Au break junction. Excitation at $\lambda_{\mathrm{form}}\simeq 530~{\rm nm}$ drives gap closure and metallic bridge formation, whereas excitation at $\lambda_{\mathrm{rup}}\simeq 407~{\rm nm}$ drives neck thinning, bridge rupture, and subsequent gap opening. Unlike conventional optical switching in metallic contacts, where illumination primarily acts via thermal expansion, the present experiment reveals oppositely directed atomic drift at different wavelengths. Time-resolved conductance traces allow us to distinguish two dynamical regimes. In the tunneling regime, exponential conductance transients measure the drift velocity of the gap coordinate for both gap closure and gap opening. In the metallic regime, the Sharvin relation converts linear $\sqrt{G/G_0}$ transients into radial neck-growth and neck-thinning velocities of comparable magnitude. These results establish optically selected atomic drift as a mechanism for reversible control of metallic nanocontacts and provide a quantitative route to follow plasmon-assisted atomic rearrangements in real time.
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All authors Werner Brämer-Escamilla, Floralba Lopez, Laila Procel, David Llerena, Carlos Sabater, Ernesto Medina