A quadratic well plays a central role in a wide variety of modern physical theories and applications. In this work, we investigate many-body dynamics in a quadratic well, using an Ising chain as a paradigmatic example. In contrast to a uniform Ising chain, where the quantum phase transition is driven by the field strength, the present system exhibits spatially varying quantum phases along the chain. Through analysis of the Majorana representation, we obtain exact solutions for localized modes, revealing a topologically degenerate spectrum in the thermodynamic limit. In the case of a finite-size quantum phase region, the Kramers-like degeneracy is lifted by a constant shift, leading to periodic oscillations for a finite-temperature thermal initial state. Numerical simulations of the magnetization, local density of state, and quench fidelity support our conclusions. Our findings enrich the understanding of many-body dynamics in a trapping field.

Altermagnets are promising candidates for next-generation low-dissipation magnonic devices due to their ultrafast spin dynamics and chiral splitting magnon bands. Hematite $\alpha \text{−}{\mathrm{Fe}}_2{\mathrm{O}}_3$, a widely recognized altermagnet with an ultralow damping constant, subterahertz magnon frequencies, and remarkable magnon properties, provides an ideal platform for exploring magnonic functionalities. Here, we combine DFT-based first-principles calculations with atomistic spin-dynamics simulations to construct a four-sublattice atomistic altermagnetic model of $\alpha \text{−}{\mathrm{Fe}}_2{\mathrm{O}}_3$ in both easy-axis and easy-plane phases. Linear spin-wave theory (LSWT) calculations confirm that the magnon bands exhibit chiral nondegeneracy along low-symmetry $K$ paths. In contrast to the easy-axis phase, the magnon bands in the easy-plane phase split into high-frequency and low-frequency branches near the Γ point. Atomistic magnon-resonance dynamical simulations further reveal the magnetic-moment precession modes with atomic resolution at the Γ point. We show that variations in the excitation field direction lead to distinct magnon-resonance modes, which give rise to the observed frequency gap in the easy-plane phase. Our work establishes a comprehensive framework for atomistic-scale magnon investigations in altermagnets, bridging first-principles calculations and atomistic spin-dynamics simulations, and provides microscopic insights into magnon dynamics in $\alpha \text{−}{\mathrm{Fe}}_2{\mathrm{O}}_3$.

We show that flexural phonons mediate tunable spin-spin interactions beyond nearest neighbors in one-dimensional systems. While longitudinal phonons in a minimal lattice model generate only nearest-neighbor couplings, the interaction mediated by pure flexural modes is infrared divergent, and tensile strain or transverse confinement regularizes it, yielding, respectively, an exponentially decaying interaction and an oscillatory interaction with an exponentially decaying envelope. In the weak-strain and weak-confinement regimes, the interaction scales as the inverse square root of the tensile strain and as the inverse fourth root of the confinement strength. Using experimentally extracted phonon dispersions together with finite-element simulations for a hexagonal boron nitride ribbon, we estimate interaction strengths of order 10 MHz. Flexural phonons thus offer a purely mechanical route to controllable multiqubit operations in solid-state spin-based quantum devices.

The temporal evolution of the nonequilibrium nearly homogeneous ferromagnetic state is analyzed within the general phenomenological spin-dynamics theory proposed by Baryakhtar, which employs the concepts of both local (relativistic) and nonlocal (exchange) spin relaxation. We demonstrate that strongly inhomogeneous spin dynamics can emerge on nanometer length scales. The mechanism responsible for this inhomogeneous dynamics is related to instabilities of the demagnetized spin state. These instabilities qualitatively modify the relaxation process toward equilibrium and may result in a dramatic underestimation of the characteristic time and amplitude of the spin dynamics. This finding can be exploited for the development of a new type of source for coherent spin-wave generation.

We theoretically investigate the superconducting surface states of topological nonsymmorphic crystalline insulators with wallpaper fermions, which are surface quasiparticles protected by a wallpaper group $p4g$ symmetry, based on a tight-binding model for the space group $P4/mbm$ (No. 127). A symmetry-based analysis shows that four types of on-site pair potentials are allowed. Using the symmetries of the wallpaper group $p4g$ and the one-dimensional topological invariants, we clarify that, for the $A_{1u}$ representation, wallpaper fermions and two Majorana Kramers pairs coexist, and hybridization between them gives rise to a double-twisted surface state and produces four peaks in the surface density of states. We further find that the mirror Chern number vanishes, indicating that our system realizes mirror-helicity-free surface states. This distinguishes superconducting wallpaper fermions from the other superconducting topological (crystalline) insulators, such as ${\mathrm{Cu}}_x{\mathrm{Bi}}_2{\mathrm{Se}}_3$ and ${\mathrm{Sn}}_{1-x}{\mathrm{In}}_x\mathrm{Te}$.

Transparent oxide semiconductors are pivotal for optoelectronic applications, but the development of $p$-type ones, especially those with ultrawide band gaps, remains a significant challenge. Recently, spinel $\mathrm{Li}{\mathrm{Ga}}_5{\mathrm{O}}_8$ (band gap approximately 5.3 eV) was reported as a robust $p$-type ultrawide band gap semiconductor, with oxygen vacancies proposed to play an important role in achieving the $p$-type conductivity. This work presents a critical first-principles reevaluation of the feasibility of $p$-type conduction in $\mathrm{Li}{\mathrm{Ga}}_5{\mathrm{O}}_8$. We find that, similar to its structural analog spinel $\mathrm{ZnG}{\mathrm{a}}_2{\mathrm{O}}_4$ and precursor β-$\mathrm{G}{\mathrm{a}}_2{\mathrm{O}}_3, \mathrm{Li}{\mathrm{Ga}}_5{\mathrm{O}}_8$ exhibits a deep, localized valence band maximum composed solely of O $2p$ orbitals, which intrinsically impedes hole generation and transport. Our analysis reveals that oxygen vacancies act as deep donors rather than shallow acceptors, directly invalidating the proposal that they play an important role in $p$-type conductivity. The Ga-on-Li antisite donor exhibits negative formation energies in the $p$-type Fermi level ($E_{\mathrm{F}}$) region, triggering a strong autocompensation mechanism that pins the $E_{\mathrm{F}}$ above midgap and fundamentally prohibits $p$-type conductivity. Therefore, $\mathrm{Li}{\mathrm{Ga}}_5{\mathrm{O}}_8$ is theoretically predicted not to be a viable $p$-type semiconductor. Furthermore, the relatively high conduction band minimum of $\mathrm{Li}{\mathrm{Ga}}_5{\mathrm{O}}_8$ inherently limits its $n$-type dopability. Although substitutional Si dopant is predicted to be a shallow donor, its prohibitively high formation energy ultimately prevents the attainment of $n$-type conductivity. Consequently, $\mathrm{Li}{\mathrm{Ga}}_5{\mathrm{O}}_8$ is established as an intrinsic insulator. This conclusion challenges recent experimental reports of $p$-type conductivity in $\mathrm{Li}{\mathrm{Ga}}_5{\mathrm{O}}_8$ and necessitates comprehensive validation for any future claims of conductivity in ultrawide band gap oxides.

Two-dimensional magnets have emerged as a promising platform for nanoscale spintronics and solid-state refrigeration. In this work, we investigate the magnetic phase transitions and magnetocaloric properties of monolayer $\mathrm{AlCr}{X}_3$ $(X=\mathrm{Se}, \mathrm{Te})$ using density functional theory calculations and spin dynamics simulations, with the consideration of exchange interaction (J), anisotropic energy (K), and Dzyaloshinskii–Moriya interaction (D). It is found that ${\mathrm{AlCrSe}}_3$ presents a labyrinth-like (LL) spin texture, while ${\mathrm{AlCrTe}}_3$ manifests a spin-spiral (SS) phase characterized by the coexistence of labyrinthine domains and skyrmions. Sizeable magnetocaloric effects (MCE) are observed; the magnetic entropy change of ${\mathrm{AlCrSe}}_3$ $\left(5.1\mu \mathrm{J}{\mathrm{m}}^{-2}{\mathrm{K}}^{-1}\right)$ is 2.5 times that of ${\mathrm{AlCrTe}}_3$ $\left(2\mu \mathrm{J}{\mathrm{m}}^{-2}{\mathrm{K}}^{-1}\right)$. Interestingly, the stronger D in ${\mathrm{AlCrTe}}_3$ facilitates a remarkable inverse magnetocaloric effect (IMCE) with an entropy change of $21\mu \mathrm{J}{\mathrm{m}}^{-2}{\mathrm{K}}^{-1}$, which is absent in ${\mathrm{AlCrSe}}_3$. A one-dimensional spin-chain model is proposed to elucidate the direct relationship between the spin deflection angle and the D/J ratio, serving as a mechanistic descriptor to clarify the microscopic origin of potential IMCE materials. In addition, we present a magnetic-state evolution map, determined by specific quantitative criteria, to analyze the thermodynamic responses across different transition regions. The present work highlights the pivotal role of Dzyaloshinskii–Moriya-interaction-mediated spin-texture evolution in modulating the thermal response of 2D magnets and provides theoretical guidance for the design of next-generation nanoscale refrigeration devices.

The optical spin Hall effect (OSHE), resulting from photonic spin-orbit coupling, has become a pivotal phenomenon in nanophotonics. While a tunable optical spin Hall effect has been achieved in liquid-crystal-based anisotropic microcavities, a more general material-independent and broadband platform remains to be explored. In this work, we demonstrate dynamic manipulation on optical spin currents in an open cavity, where the strength and direction of the effective magnetic field experienced by photons can be precisely controlled. By exploring the cavity length dependence of the TE-TM mode splitting and photonic spin pattern both experimentally and theoretically, we unambiguously reveal the mechanism that governs the tunable OSHE. This approach relies on the intrinsic polarization properties of planar cavity modes, and is applicable for photonic spin control in any hybrid light-matter system within a broad optical bandwidth.

Understanding thermal transport in two-dimensional (2D) materials at cryogenic temperatures is essential for emerging low-temperature nanoelectronics, yet remains largely unexplored because of the lack of a predictive theoretical framework. Here, we develop a rigorous, accelerated, mode-resolved first-principles approach that enables the quantitative prediction of thermal conductivity in 2D materials down to 5 K. Using monolayer ${\mathrm{MoSe}}_2$ ribbons as a model system, we explicitly account for anharmonic, isotope, and boundary scattering, as well as finite-size effect, going beyond the conventional Matthiessen approximation. We reveal qualitatively distinct transport physics arising from reduced dimensionality. Unlike three-dimensional (3D) systems, where boundary-limited transport approaches the conventional Casimir regime with a $T^3$ dependence, 2D ${\mathrm{MoSe}}_2$ ribbons exhibit no well-defined Casimir regime; instead, their thermal conductivity follows geometry-sensitive power-law scaling ranging from $T^{1.9}$ to $T^{0.7}$. In addition, strain effects exhibit strong temperature- and size-dependent behavior. Strain effects are modest in nanoscale ribbons (∼100 nm) in which harmonic properties dominate, but enhance out-of-plane flexural branch phonon scattering in larger samples (∼1 mm), reducing conductivity by up to 50% at low temperatures. These results establish a quantitative framework for cryogenic heat transport in 2D materials with direct implications for the design of cryogenic 2D devices.

Understanding relaxation in isolated quantum many-body systems remains a central challenge. Recently, the quantum Mpemba effect (QME)—a counterintuitive relaxation phenomenon—has attracted considerable attention and has been extensively studied in systems with global symmetries. Here, we study the QME in gauge theories with massive local gauge symmetries. In the lattice Schwinger model, we demonstrate that the gauge structure of the reduced density matrix of a subsystem is entirely determined by the initial state and remains unchanged during the time evolution. We then investigate whether subsystem gauge symmetry can be dynamically restored following a symmetric quench. Analytical and numerical results show that, when the Maxwell term is zero, subsystem gauge-symmetry restoration fails due to an emergent conservation law. However, for any finite Maxwell term, subsystem gauge symmetry is restored in the thermodynamic limit. Based on these results, we systematically construct a families of initial states exhibiting the QME. We further explore the QME in the quantum link model, a truncated lattice Schwinger model, which has been realized in experiments. Moreover, we propose an experimentally accessible order parameter that correctly captures the QME. Our work demonstrates the generality of the quantum Mpemba effect even in the local gauge symmetries, and is directly relevant to ongoing quantum-simulation experiments of gauge theories.

The current interest in dimerization spans several scientific areas. In quantum computation, chains of spin dimers contribute as a medium of coherent quantum state transfer, which is essential for the storage and processing of quantum information. In biophysics, molecular dimers are widely used to understand the dynamics of proteins and DNA. In this sense, we believe it might be of interest to examine the dynamics of spin models with multiple interactions in which a dimerization phase can be induced. In this work, we investigate the dynamics of the spin-1/2 Ising ladder with four-spin plaquette interaction subjected to a random transverse magnetic field at the infinite-temperature limit. The system dynamics is analyzed using the recurrence relations method, which enables the calculation of time-dependent spin autocorrelation functions and their associated spectral densities, considering the effects of randomness in the magnetic field and the multispin interaction strength. Our results reveal that the disorder leads to the emergence of multipeak structures in the spectral density, suggesting field-induced dimerized-spin states, and a dynamical transition occurs as the disorder increases. We highlight interesting qualitative analogies between our findings and the dimerization process in quantum computing and biophysics.

Two-dimensional (2D) magnets offer a rich platform for exploring emergent spin phenomena due to their unique and diverse magnetic properties. Beyond intrinsic magnetism, external manipulation—such as defect engineering, molecular adsorption, or charge doping—offers powerful routes to control their magnetic behavior. In this work, we demonstrate that localized electron polarons provide an effective means to modulate magnetism in 2D magnets. Using first-principles calculations, we investigate polaron formation in monolayer ${\mathrm{MnPS}}_3$ and compute the resulting changes in magnetic exchange interactions. Our results reveal that polarons can locally break magnetic symmetry and induce anisotropic exchange couplings, highlighting an alternative mechanism for tuning magnetic textures. This insight opens promising pathways for designing atomic-scale control of magnetism, with potential impact on spintronic technologies.

We theoretically study the effect of spin-orbit coupling (SOC) on anomalous quantum oscillations in InAs/GaSb quantum wells. By comparing different cases, we show that SOC induces two opposing effects on anomalous quantum oscillations: it suppresses the oscillations in the clean case, while enhancing them in the disordered case. Using an effective model, we analyze in detail the origins of anomalous oscillations in both clean and disordered cases. Based on these origins, we explain why SOC suppresses or enhances the anomalous oscillations in different cases, thereby extending the understanding of the conventional theory. Moreover, in the disordered case, SOC can induce a phase shift in the anomalous oscillations. We further identify a parameter window where the anomalous oscillations are significantly enhanced in the presence of both disorder and SOC. These results provide a theoretical basis for understanding the role of SOC in anomalous quantum oscillations.

The metallic kagome compound ${\mathrm{Sc}}_3{\mathrm{Mn}}_3{\mathrm{Al}}_7{\mathrm{Si}}_5$ has attracted attention as a candidate platform where geometric frustration and itinerant electrons may cooperate to stabilize a quantum-disordered magnetic ground state. Here, we combine bulk thermodynamic probes, low-noise focused-ion-beam-device transport, and comprehensive ${}^{55}\mathrm{Mn}$ nuclear magnetic resonance (NMR) measurements to elucidate the low-temperature spin dynamics of this system. The bulk data reveal strongly reduced magnetic entropy, a negative magnetoresistance arising from spin scattering, and field-dependent transport indicates the spin fluctuations, while showing no signatures of long-range magnetic order. NMR provides a direct local view of the correlated Mn moments: the nuclear spin-spin relaxation time $T_2$ exhibits a pronounced low-temperature enhancement driven by an indirect internuclear coupling through electronic spin fluctuations, whose temperature and distance dependencies point to partially gapped low-energy spin excitations. The spin-lattice relaxation rate $T_1^{-1}$ displays a broad peak near $10\mathrm{K}$ that may originate from spin-singlet pairing and coincides with the resistivity crossover and a subtle heat-capacity anomaly. Together, our results suggest that ${\mathrm{Sc}}_3{\mathrm{Mn}}_3{\mathrm{Al}}_7{\mathrm{Si}}_5$ hosts an unconventional correlated state dominated by frustrated, gapped spin dynamics, placing it among the rare metallic kagome systems proximate to a quantum spin liquid.

Altermagnets, which encompass a broad landscape of materials, are compensated collinear magnetic phases in which the antiparallel magnetic moments are related by a crystalline rotation. Here, we argue that collinear altermagneticlike states can also be realized in lattices with an odd number of sublattices, provided that the electronic interactions promote nonuniform magnetic moments. We demonstrate this idea for a kagome metal whose band filling places the Fermi level close to the van Hove singularity. Combining phenomenological and microscopic modeling, we show that the intertwined charge density-wave and loop-current instabilities of this model lead to a wide parameter range in which orbital ferromagnetic, antiferromagnetic, and altermagnetic phases emerge inside the charge-ordered state. In the presence of spin-orbit coupling, their electronic structures display the usual spin-split fingerprints associated with the three types of collinear magnetic order. We discuss the possible realization of orbital altermagnetic phases in the ${A\mathrm{V}}_3{\mathrm{Sb}}_5$ family of kagome metals.

Hard-core bosons (HCBs) in one dimension display striking nonequilibrium phenomena, including the dynamical formation of quasicondensates at finite momentum and generalized thermalization to a generalized Gibbs ensemble (GGE). These effects, rooted in the integrability of the HCB model, have been challenging to probe experimentally due to the lack of direct momentum-space access in optical lattice platforms. Noisy intermediate-scale quantum devices offer a complementary approach, enabling single-site resolution, precise state preparation, and direct measurement of correlation functions. Here, we present a quantum simulation of HCB dynamics on IBM superconducting-qubit hardware and compare the results with exact numerics and with Quantinuum's high-fidelity noisy trapped-ion emulator. Using algebraic circuit compression to eliminate Trotter error, we simulate quenched HCB dynamics across long timescales and observe signatures consistent with the theoretically predicted dynamical quasicondensation. IBM reproduces the short-time formation of peaks at $k=\pi /2$. At late times, IBM data tend toward behavior more consistent with a conventional Gibbs ensemble (GE), whereas the Quantinuum emulator remains closer to the integrable GGE prediction. These results illustrate the sensitivity of integrable many-body dynamics to noise and suggest that the preservation of GGE signatures may provide a useful physics-based diagnostic for quantum-simulation performance.

In continuous quantum field theories, the entanglement entropy of a subsystem with sharp corners on its boundary exhibits a universal corner-dependent contribution. We study this contribution through the lens of lattice discretization, and demonstrate that this corner dependence emerges naturally from the geometric structure of infinite projected entangled pair states (iPEPS) on discrete lattices. Using a rigorous counting argument, we show that the bond dimension of an iPEPS representation, which serves as a bound on the entanglement, exhibits a corner-dependent term that matches the predicted term in gapped continuous systems. Crucially, we find that this correspondence only emerges when averaging over all possible lattice orientations and origin positions, revealing a fundamental requirement for properly discretizing continuous systems. Our results provide a geometric understanding of entanglement corner laws and establish a direct connection between continuum field-theory predictions and the structure of discrete tensor-network representations. We extend our analysis to gauge-invariant systems, where lattice corners crossed by the bipartition boundary contribute an additional corner-dependent term. These findings offer new insights into the relationship between entanglement in continuous and discrete quantum systems.

At high frequency, a periodically driven quantum spin-1/2 system can emulate a chiral spin liquid (CSL) described by an effective static local chiral Hamiltonian. In contrast, at low frequency these settings realize “Swap” models exhibiting anomalous CSL phases, in which one-way spin transport occurs at the edge although the bulk time-evolution operator over one period is trivial. In this work, we explicitly construct a family of Floquet quantum spin-1/2 models on the square lattice implementing Swap models to investigate the stability of the anomalous CSL under frequency detuning and the transition to the high-frequency regime. We used the average-energy spectrum on finite-size tori and cylinders to unfold the Floquet quasienergy spectrum over the whole frequency range and obtain the geometrical Berry phases. This enabled us to identify three regimes upon increasing detuning: (i) a finite-size regime (with no folding of the Floquet spectrum), (ii) an intermediate (narrow) regime with folding and very few resonances, and (iii) a regime with an increased density of resonances suggesting heating. At small detuning, edge modes are revealed by spectroscopic tools and from the Streda response of the system, giving access to the anomalous winding number. The analysis of all the data suggests that the anomalous CSL is not continuously connected to the high-frequency CSL. We also discuss the possible occurrence of a long-lived prethermal anomalous CSL.