Recently, the driven dynamics of localization phase transition have garnered growing interest. However, studies so far have mainly considered initial localized states, whose driven dynamics follow the Kibble-Zurek mechanism (KZM). In this study, we investigate the driven dynamics of the localization phase transition in the Aubry-André model starting from a gapless extended state, which violates the adiabatic-impulse scenario of KZM. By linearly driving the quasiperiodic potential strength across the critical point, we numerically simulate the driven dynamics and analyze the scaling behavior of both the inverse participation ratio ($\mathcal{I}$) and the dynamic deviation from the instantaneous ground-state energy $\left(\mathcal{D}\right)$. We demonstrate that the driven dynamics starting from initially extended states satisfies the criterion for the applicability of KZM and its extension, finite-time scaling (FTS). The scaling functions governing the driven dynamics of both $\mathcal{I}$ and $\mathcal{D}$ have been derived based on FTS and numerically validated. We found that the scaling functions exhibit significant differences at large $R$ and small $R$, and also differ considerably from the scaling functions when the initial state is localized, highlighting the crucial role of initial-state behavior. The established scaling laws remain robust across a wide range of system sizes and driving rates, providing testable predictions for experimental realizations.

Electronic conduction at the atomic scale can be described by Landauer’s formalism. In single-atom point contacts of noble metals like Au and Ag, there is just one channel open between both electrodes and the conductance is very close to the quantum of conductance $G\approx G_0=\frac{2e^2}{h}$, with the factor of two coming from spin degeneracy. The magnetoconductivity of atomic size contacts has been studied for numerous systems, unveiling local Kondo screening, magnetic order, and spin-polarized currents. However, these have been mostly performed in elements with multiple open conduction channels where $G$ differs from $G_0$. The realization of a magnetically active conductor with a single-open channel remains difficult to achieve. Here, we present measurements of the electronic conductance of single-channel Au and Ag atomic size contacts in magnetic fields up to 20 T. We observe a decrease in $G$ which goes up to about 15% in many Au contacts at 20 T. We perform calculations and find that pure Ag and Au do not present a strong field dependence of $G$, in agreement with previous results at smaller magnetic fields. We also find, however, that residual ${\mathrm{O}}_2$ molecules attached close to the contact produce an induced spin-polarized current, which leads to a decrease in $G$. We discuss the role of the magnetic response of the electrodes in the jump-to-contact. Our results suggest that single channel atomic size conductors with a sizable response to a magnetic field can be built by combining noble metals and magnetically active molecular systems.

First-principles modeling of dense hydrogen is crucial in materials and planetary sciences. Despite its apparent simplicity, predicting the ionic and electronic structure of hydrogen is a formidable challenge, and it is connected with the insulator-to-metal transition, a century-old problem in condensed matter. Accurate simulations of liquid hydrogen are also essential for modeling gas giant planets. Here, we perform an exhaustive study of the equation of state of hydrogen using density functional theory (DFT) and quantum Monte Carlo simulations. We find that the pressure predicted by DFT may vary qualitatively when using different functionals. The predictive power of first-principles simulations is restored by validating each functional against higher-level wavefunction theories, represented by computationally intensive variational and diffusion Monte Carlo calculations. Our simulations provide evidence that hydrogen is denser at planetary conditions, compared to currently used equations of state. For Jupiter, this implies a lower bulk metallicity (i.e., a smaller mass of heavy elements). Our results further amplify the inconsistency between Jupiter’s atmospheric metallicity measured by the Galileo probe and the envelope metallicity inferred from interior models.

${\mathrm{KTaO}}_3$ (KTO) is an incipient ferroelectric, characterized by a softening of the lowest transverse optical (TO) mode with decreasing temperature. Cooper pairing in the recently discovered KTO-based heterostructures has been proposed to be mediated by the soft TO mode. Here, we study the electron coupling to the zone-center odd-parity modes of bulk KTO by means of relativistic Density Functional Perturbation Theory (DFPT). The coupling to the soft TO mode is by far the largest, with comparable contributions from both intraband and interband processes. Remarkably, we find that for this mode, spin nonconserving matrix elements are particularly relevant. We develop a three-band microscopic model with spin-orbit-coupled $t_{2g}$ orbitals that reproduces the main features of the ab initio results. For the highest energy band, the coupling can be understood as a “dynamical” isotropic Rashba effect. In contrast, for the two lowest bands, the Rashba-like coupling becomes strongly anisotropic. The DFPT protocol implemented here enables the calculation of the full electron-phonon coupling matrix projected onto any mode of interest, and it is easily applicable to other systems.

Spin-exchange collisions have been widely studied in recent years, and various quantum-mechanical scattering approaches have been developed to calculate the rates. However, these methods based on global knowledge of wave functions can be computationally demanding, are limited to small systems, and do not offer a mechanistic interpretation. Here, we present a semiclassical transition-state theory (SCTST) derived from first principles to describe the nonadiabatic transition between two states that differ only in their spins, where classical TST and Landau-Zener theory fail. We apply our theory to describe the spin-exchange collision between the nuclear spin of ${}^3\mathrm{He}$ and the electronic spin of ${}^{23}\mathrm{Na}$. SCTST reveals that the reaction proceeds via temperature-dependent transition states, determined by an intricate compromise between minimizing the activation energy and maximizing the hyperfine coupling. It further demonstrates the importance of quantum delocalization effects prevalent in spin exchange even when tunneling is suppressed and successfully explains the observed weak temperature dependence of the rate. Finally, we showcase the power of SCTST by making predictions for the ${}^3\mathrm{He}+{\mathrm{CH}}_3$ spin-exchange collision in full dimensionality, where we find that the internal degrees of freedom induce symmetry-broken transition states.

We report the observation of discrete supercurrent suppression steps arising from quantum Cooper-pair tunneling in superconductor-graphene-superconductor (SGS) Josephson junctions under near-infrared illumination. This quantum phenomenon remains robust against variations in photon energy, optical power, bath temperature, and dc bias. The nearly identical step spacing observed in SGS Josephson junctions with different graphene channel lengths indicates the dominant role of the superconductor-graphene interface in governing Cooper-pair transport. In contrast, the discrete steps vanish in the negative differential resistance regime, where quasiparticle transport dominates, confirming their microscopic Cooper-pair tunneling origin.

We study a type of solitonic Andreev bound state (ABS) in a Corbino-geometry Josephson junction created on a two-dimensional electron gas (2DEG). The Josephson junction is subjected to a weak magnetic flux that induces a fluxoid mismatch between the inner disk and outer ring superconductors. The mismatch produces a Josephson vortex (phase soliton) that binds unconventional spinful but chargeless ABSs, analogous to Jackiw-Rebbi solitonic states. The position around the Josephson junction of the trapped ABSs can be controlled externally by a junction phase bias. As the solitonic ABSs are shuttled around the Josephson junction, the 2DEG spin-orbit coupling induces a geometric precession of their spin. We argue that these solitonic ABSs constitute a natural candidate for a type of superconducting Andreev spin qubit, dubbed solitonic Andreev spin qubit (SASQ), that combines features of Andreev spin qubits and geometric spin qubits. Holonomic single-qubit SASQ operations are induced through soliton shuttling, with the resulting SU(2) trajectories densely covering the qubit Bloch sphere. Effects of disorder, nonholonomic SASQ dynamics, and other aspects of qubit operation are also analyzed.

We investigate GaAs/AlGaAs heterostructure membranes with a metasurface made up of a grating of two-dimensional electron system strips. Experiments have revealed a strong plasma resonance in the transmission of the metasurface. We have found that a collective effect from the superlattice, along with lateral screening between the strips, leads to the emergence of a plasmon mode in the metasurface under study. Furthermore, we develop an analytical approach that accurately describes the behavior of the discovered superlattice plasmon mode, providing insights into the fundamental physics of plasmonic metasurface systems.

We determine whether excitonic effects affect predictions of dark matter (DM)-electron scattering rates by calculating the energy- and momentum-dependent energy-loss function, including electron-hole interaction excitonic effects, for the DM scintillating detector materials GaAs and NaI. By comparing our results using the Bethe-Salpeter equation in the framework of many-body perturbation theory, which explicitly includes excitonic effects, with those using the quasiparticle random-phase approximation, which includes only electron-electron interaction and crystal local-field effects, we find that excitonic effects in NaI significantly increase the predicted scattering rate at low energy and as a result improve the cross-section sensitivity considering a realistic background. In contrast, the predicted scattering rate and the DM-electron scattering cross section for GaAs are minimally affected by excitonic effects.

The nitrogen-vacancy (NV) center in diamond has become a widely used platform for quantum sensing. The four NV axes in monocrystalline diamond specifically allow for vector magnetometry, with magnetic-field sensitivities reaching down to $\mathrm{fT}/\sqrt{\mathrm{Hz}}$. The current literature primarily focuses on improving the precision of NV-based magnetometers. Here, we study the experimental accuracy of determining the magnetic field from measured spin-resonance frequencies via solving the NV Hamiltonian. We derive exact, analytical, and fast-to-compute formulas for calculating resonance frequencies from a known magnetic-field vector, and vice versa (formulas for calculating the magnetic-field vector from measured resonance frequencies). Additionally, the accuracy of often-used approximations is assessed. Finally, we promote using the Voigt profile as a fit model to determine the linewidth of measured resonances accurately. An open-source Python package accompanies our analysis.

Calcium carbonate ($\mathrm{Ca}{\mathrm{CO}}_3$) is a widely occurring mineral that is crucial to many natural and synthetic processes. $\mathrm{Ca}{\mathrm{CO}}_3$ crystallizes in three anhydrous polymorphs and often serves as a model system to study nucleation and growth phenomena. In this article, we employ coherent diffraction imaging coupled with wide-angle x-ray diffraction (CXDI-WAXD) to investigate the three-dimensional (3D) morphology and crystal structure of $\mathrm{Ca}{\mathrm{CO}}_3$ microparticles crystallized under different reaction temperatures. We report particles containing both vaterite and aragonite, which we interpret as an intermediate growth stage between early vaterite and later aragonite formation. The results are based on the density variations observed in the 3D tomographic CXDI images, x-ray diffraction, and focussed ion beam-transmission electron microscopy study of the mixed vaterite-aragonite microparticles. A computational study based on Monte Carlo and molecular dynamics energy minimization was used to identify the small energetic variations between the different crystalline forms of $\mathrm{Ca}{\mathrm{CO}}_3$. The results presented in this article provide a better understanding of the morphology-structure correlation for $\mathrm{Ca}{\mathrm{CO}}_3$ polymorphs, depicting a transitional stage where both vaterite and aragonite coexist.

We present a detailed and self-contained theoretical study of polarons in two-dimensional (2D) polar materials, which extends the classical macroscopic theory of Fröhlich polarons to the 2D case. The theory is fully determined by experimentally accessible parameters, the static and optical 2D polarizabilities of a monolayer, the frequency of transverse optical phonons, and the effective mass of charge carriers. We define a single dimensionless parameter, which characterizes the coupling of electrons with longitudinal optical phonons, analyze both weak- and strong-coupling regimes, and adapt the Feynman variational path-integral approach for a high-quality interpolation between these limits. Our results provide insight into the ground-state energy and effective mass of polarons in modern 2D polar monolayers.

Molecular nanomagnets have garnered significant attention in recent years thanks to their unique potential in quantum information processing as molecular qudits and in high-density memory encoding as single-molecule magnets. However, fully unlocking the potential of these systems requires a comprehensive understanding of the interplay between the various mechanisms that govern their relaxation dynamics, which remains a noncompletely understood phenomenon. In this work, we employ a cost-effective semi-ab initio approach to model the magnetization relaxation dynamics in a testbed Dy-based single-molecule magnet and determine the effects of applied external pressure on the interplay between various mechanisms, such as coupling with molecular vibrations and quantum tunneling. Ab initio phonon calculations are validated by direct comparison with inelastic neutron scattering experiments, which are used for the first time to investigate pressure-induced modifications of phonons and vibrations in a molecular nanomagnet. The combination of our theoretical approach with different experimental techniques allows us to predict an overall acceleration of the relaxation dynamics under pressure, disentangling the role of different ingredients, such as crystal field axiality and phonons.

We challenge two foundational principles of localization physics by analyzing conductance fluctuations in two dimensions with unprecedented precision: (1) the Thouless criterion, which defines localization as insensitivity to boundary conditions, and (2) that symmetry determines the universality class of Anderson localization. We reveal that the fluctuations of the conductance logarithm fall into distinct subuniversality classes inherited from Kardar-Parisi-Zhang (KPZ) physics, dictated by the lead configurations of the scattering system and unaffected by the presence of a magnetic field. Distinguishing between these probability distributions poses a significant challenge due to their striking similarity, requiring sampling beyond the usual threshold of $\sim {10}^{-6}$ accessible through independent disorder realizations. To overcome this, we implement an importance sampling scheme—a Monte Carlo approach in disorder space—that enables us to probe rare disorder configurations and sample probability distribution tails down to ${10}^{-30}$. This unprecedented precision allows us to unambiguously differentiate between KPZ subuniversality classes of conductance fluctuations for different lead configurations, while demonstrating the insensitivity to magnetic fields.

The spin states of the nitrogen vacancy (${\mathrm{NV}}^{-}$) center in diamond are used in, among others, quantum computing, nanoscale imaging, and magnetic field sensing, and have been proposed for fundamental physics experiments. The states of ${\mathrm{NV}}^{-}$ centers are traditionally measured using the spin-state-dependent photoluminescence—a destructive and often inefficient measurement scheme. In this article, using a single laser beam as a pump and a probe, we measure the spin states of the ${\mathrm{NV}}^{-}$ centers nondestructively using the Faraday effect at room temperature. Using the optical selection rules and the helicity-dependent absorption, we identify the optical transitions of the ${\mathrm{NV}}^{-}$ center responsible for the Faraday effect and confirm the existence of spin-orbit coupling in such centers at room temperature. Our results indicate that experiments such as NV spin-photon entanglement and electromagnetically induced transparency are viable in ambient conditions. Finally, using the Faraday effect, we develop a magnetic field sensor and argue that, with the inclusion of an optical cavity, a femtotesla-level magnetic field sensitivity can be achieved.

We present a theory of geodynamics in a spacetime crystal based on an event wave packet constructed from the Floquet-Bloch waves, which involves not only a scalar dispersion function but also a Berry curvature tensor in the phase space manifold of spacetime and the reciprocal quasi-energy-momentum. In the presence of structural deformation, this theory is naturally extended into a covariant form with the introduction of a lattice connection constructed out of the gradients of the local lattice vectors. This geometric framework reveals three distinct gravitational forces: lattice deformation gravity, dispersion gravity, and Berry curvature gravity. These forces manifest as distinct, experimentally tunable connection and metric terms in the geodynamics, establishing a framework for engineering artificial spacetime by controlling lattice strain, band structure, and wave function topology. Our work provides a direct conceptual link between general relativity and condensed matter physics, opening a path toward the laboratory realization of novel gravitational phenomena.

Machine-learning (ML) models trained on Ising spin configurations have demonstrated surprising effectiveness in classifying phases of Potts models, even when processing severely reduced representations that retain only two spin states. To unravel this remarkable capability, we identify a family of alternative order parameters for the $q=3$ and $q=4$ Potts models on a square lattice, constructed from the occupancies of secondary and minimal spin states rather than the conventional dominant-state order parameter. Through systematic finite-size scaling analyses, we demonstrate that these quantities, along with a magnetizationlike quantity derived from a reduced spin representation, accurately capture critical behavior, yielding critical temperatures and exponents consistent with established theoretical predictions and numerical benchmarks. Furthermore, we rigorously establish the fundamental relationships between these alternative (quasi)order parameters, demonstrating how they collectively encode criticality through different aspects of spin configurations. Our results clarify, within this specific setting, how reduced spin representations can retain the essential thermodynamic information needed for identifying critical behavior. Taken together, this work establishes a concrete bridge between Ising-trained ML models and critical phenomena in Potts systems by showing that Potts criticality can be encoded in more compact, nontraditional forms, thereby opening avenues for discovering analogous order parameters in broader spin systems.

We analyze the universality classes of phase transitions in a variety of nonlinear voter models. By mapping several models with symmetric absorbing states onto a canonical model introduced in previous studies, we confirm that they exhibit a Generalized Voter transition. We then propose a canonical mean-field model that extends the original formulation by incorporating a noise term that eliminates the absorbing states. This generalization gives rise to a phase diagram featuring two distinct types of phase transitions: a continuous Ising transition and a discontinuous transition we call Modified Generalized Voter. These two transition lines converge at a tricritical point. We map diverse noisy nonlinear voter models onto this extended canonical form. Using finite-size scaling techniques above and below the upper-critical dimension, we show that the continuous transition of these models belongs to the Ising universality class in their respective dimensionality. We also find universal behavior at the tricritical point. Our results provide a unifying framework for classifying phase transitions in stochastic models of opinion dynamics with both nonlinearity and noise.