The Peierls-Boltzmann transport equation (PBE), which governs nonequilibrium phonon transport, suffers from the curse of dimensionality because of its high-dimensional phase space including both real and modal spaces. We explore the use of matrix product states (MPS) for numerical simulation of the PBE. We show that an MPS configuration based on scattering events combined with a dimensionless form of the solution can drastically increase the locality of correlations between tensors in the MPS representation, enhancing its effectiveness in dimension reduction. We further examine the effects of index ordering in an MPS and find that the highest locality is achieved when tensor chains associated with both real and modal spaces are connected at the coarsest grid to each other in the center of the MPS. Using this optimal configuration and a solver inspired by the density matrix renormalization group, we solve the PBE discretized by a finite volume method (FVM). The solution is obtained for crystalline silicon across ballistic, quasiballistic, and diffusive transport regimes. An MPS truncated to a compression ratio of ${10}^{-3}$ suffices to reproduce reference solutions with high fidelity. The computational cost scales sublinearly with the number of grid points in both real and modal spaces, achieving roughly an order of magnitude reduction in computational time compared to the FVM with sparse matrix operation.

The anisotropy of black phosphorene (BP) and calcite endows light transmission with novel tunable features. A multilayer dielectric structure incorporating BP-calcite is designed. Using the transfer matrix method, the modulation of light reflectance, transmittance, and absorptance by incident light as well as the twist angles of BP and calcite is systematically investigated. When the principal axes of BP and calcite are rotated within the plane of incidence, copolarized and cross-polarized reflected and transmitted waves are induced, thereby enabling flexible modulation of the magnitude and peak positions of light absorption under TE and TM polarizations, which vary monotonically with the increase of twist angles. Under grazing incidence of TE mode, with a fixed twist angle of calcite, absorption near 20 THz exhibits robust characteristics, while other absorption peaks show a blueshift with increasing BP twist angle. In contrast, with a fixed BP twist angle, absorption peaks above 40 THz exhibit a redshift with increasing calcite twist angle. The generation mechanism of cross-polarization is analyzed and effectively enhanced using a Kretschmann-like structure. This study provides an important theoretical foundation for the regulation of light transmission in multilayer anisotropic materials, enhancement of cross-polarization, and the design and fabrication of optical functional devices.

A deformation of a graphene sheet changes more than the positions of the atoms. In the low-energy Dirac theory it also produces geometric electron-phonon vertices. One of these vertices acts as an emergent phonon gauge field ${\mathcal{A}}_{\mu }$, which couples to the same Dirac current as the electromagnetic vector potential. This shared current vertex gives a direct route from mechanics to electronics: a moving deformation can generate a transverse electric current, and a deformation pattern with emergent phonon flux can bind electric charge. We show that the coefficient of this mixed electromechanical response is the parity-odd current-current correlator of a massive Dirac cone. For an insulating cone the coefficient is the one-cone Chern-Simons value, while for a doped cone in the local regime it is reduced by the Berry curvature factor $m/\left|\mu \right|$. We apply the response to explicit deformations. A traveling flexural wave generates a transverse second-harmonic current; a static ripple mixed with a dynamic phonon generates a transverse current at the drive frequency; and two noncollinear modes can generate charge modulation through the emergent phonon flux. We keep the spin and valley sum explicit, so the paper shows when the one-cone anomaly becomes a charge current in graphene and when it instead appears in a valley, spin, or spin-valley channel. For sublattice-gapped graphene with a valley-odd deformation gauge coupling, the two valleys add rather than cancel. The experimentally sharp signature is a transverse electrical signal at twice the flexural-wave frequency, with a phase fixed by the sign of the sublattice gap and a gate dependence that crosses over from a gap plateau to a $1/\left|\mu \right|$ decay. These direction, phase, frequency, and gate-voltage selection rules give clean tests of the anomaly-induced electromechanical channel in deformed graphene.

Chirality induced by rolling a two-dimensional material into a spiral geometry reshapes its electronic band structure. In this work we theoretically investigate the topological properties of carbon nanoscrolls under an axial magnetic field, focusing on structures in which chirality is encoded through shifted edge alignments. In contrast to unshifted structures, where mirror symmetry pins the Dirac cones to half a flux quantum, chiral carbon nanoscrolls lack this symmetry, and Dirac cones emerge at magnetic flux values away from half a flux quantum. We demonstrate that these Dirac cones are topologically protected by combined inversion–time-reversal symmetry and remain robust even when sublattice symmetry is broken. Furthermore, we show that the number of Dirac cones and their real-space probability distributions depend on the number of turns and the magnetic field strength. Our study elucidates the role of chirality in the band topology of nanoscroll geometries.

${\mathrm{Bi}}_4{\mathrm{Te}}_3$ has been first realized as an element of the adaptive series ${\left({\mathrm{Bi}}_2\right)}_m{\left({\mathrm{Bi}}_2{\mathrm{Te}}_3\right)}_n$—deriving from stacking metallic Bi and topological insulator ${\mathrm{Bi}}_2{\mathrm{Te}}_3$ blocks—and studied for its promising thermoelectric properties. Recently, ${\mathrm{Bi}}_4{\mathrm{Te}}_3$ has also been found as a dual topological insulator hosting a complex band structure with three Dirac cones in $k$ space. Here we report measurements of the optical conductivity of five ${\mathrm{Bi}}_4{\mathrm{Te}}_3$ thin films with thickness varying from 11 to 32 nm. This extensive study, based on terahertz time-domain spectroscopy and Fourier-transform infrared spectroscopy, provides a broadband optical conductivity. By employing a Kramers-Kronig constrained Drude-Lorentz model, the spectral contributions to the optical conductivity of each sample have been singled out. In contrast to an ideal topological insulator—with perfectly insulating bulk—in ${\mathrm{Bi}}_4{\mathrm{Te}}_3$ far-infrared and mid-infrared bands indicate the presence of localized massive carriers, which dope the bulk system, as also observed in chemically compensated single crystals of other bismuth-based topological insulators. In addition, the localized bulk charges strongly renormalize the electronic mass. The charge dressing enhances as the thickness increases, indicating a trivial metallic behavior of ${\mathrm{Bi}}_4{\mathrm{Te}}_3$ thin films. This study elucidates the inner relationship between the optical properties of a dual topological insulator like ${\mathrm{Bi}}_4{\mathrm{Te}}_3$ and its complex band structure, since the detection of the topological massless carriers by optical measurements is prevented by the occurrence of novel and unusual conductive properties.

Quantum circuits have been shown to be a fertile ground for realizing long-range entangled phases of matter. While various quantum double models with nonchiral topological order have been theoretically investigated and experimentally implemented, the realization and characterization of chiral topological phases have remained less explored. Here we show that chiral topological phases in spin systems, i.e., chiral spin liquids, can be prepared in quantum circuits using the variational quantum eigensolver (VQE) framework. On top of the VQE ground state, signatures of the chiral topological order are revealed using the recently proposed tangent-space excitation ansatz for quantum circuits. We show that both topological ground-state degeneracy and the chiral edge mode can be faithfully captured by this approach. We demonstrate our approach using the Kitaev honeycomb model, finding excellent agreement between the low-energy excitation spectrum on quantum circuits and the exact solution in all topological sectors. Further applying this approach to a non-exactly solvable chiral spin liquid model on a square lattice, the results suggest that this approach works well even when the topological sectors are not exactly known.

Flat-band systems, characterized by dispersionless energy bands and compact localized states, have emerged as promising platforms for exploring strongly correlated phenomena in condensed-matter physics. While extensively studied in electronic systems, their potential in nanophotonics and thermal management remains underexplored. In this work, we investigate the flat-band phenomena in quasi-one-dimensional stub lattices composed of silicon carbide nanoparticles on the basis of many-body radiative heat transfer. Employing the dipole approximation, we account for long- and short-range interactions to compute band structures under periodic and open boundary conditions, revealing dispersionless flat bands and compact localized states characterized by high inverse participation ratios and sublattice-selective dipole distributions due to geometrical frustration. Boundary conditions significantly modulate radiative heat transfer between chain ends, exhibiting distinct spectral peaks and $l^{-2}$ scaling in long chains up to 500 unit cells. Furthermore, temporal dynamics is analyzed via eigenmode decomposition of the linearized response matrix, showing that the stub geometry suppresses the spatial spreading of local thermal perturbations and confines the temperature response more strongly than the one-dimensional periodic chain. These findings provide insight into how flat-band-inspired geometry shapes near-field radiative heat transport and offer a route to boundary-controlled nanophotonic thermal management.

The large intrinsic spin current in magnetic Weyl semimetals provides a promising platform for spin-orbit torque (SOT) devices. Here, we demonstrate SOT-driven magnetization switching in a synthetic antiferromagnet (SAF) composed of a ${\mathrm{Co}}_2\mathrm{MnGa}$ (CMG)/MnGa bilayer. In this heavy metal-free structure, CMG film functions simultaneously as a spin current source and as a magnetic layer. Macrospin simulations confirm the self-induced switching mechanism in the bilayer. The SOT generated by CMG switches the MnGa layer, which in turn triggers the reversal of the CMG layer via strong antiferromagnetic exchange coupling. These results elucidate the spin dynamics in SAFs and provide a pathway toward SOT devices with self-induced magnetization switching.

We theoretically study the emergence of topological magnons in electron-magnon coupled systems. The magnon dispersion in a ferromagnet usually possesses an antiunitary symmetry consisting of a combination of time-reversal and spin-rotation operations in the absence of a Dzyaloshinskii-Moriya (DM) interaction, preventing the appearance of topological magnons. When a spin system is coupled to itinerant electrons, we find that the magnon band structure of the spin system experiences time-reversal symmetry breaking with the electron-magnon interaction via the exchange coupling, where topological magnons arise without requiring strong DM. Specifically, we consider a heterostructure consisting of a ferromagnetic insulator and a transition metal dichalcogenide monolayer and investigate the topological gap opening in magnon bands. Our findings reveal that even trivial ferromagnets can host topological magnons via coupling to itinerant electronic systems.

Topological singularities are fundamental organizing principles in wave physics, yet whether nonlinearity can intrinsically generate new singular structures remains largely unexplored. Here, we show that even a minimal nonlinear system—consisting of a single Kerr-nonlinear cavity coupled to a linear cavity—supports a rich hierarchy of topological singularities with no counterpart in linear two-mode systems. By analyzing the full nonlinear spectrum, we identify multiple classes of degeneracies, including higher-order exceptional-like singularities, nondefective degeneracies, and unconventional second-order singularities exhibiting anomalous scaling behavior. To rigorously define their topology, we introduce an isospectral embedding that maps the nonlinear eigenproblem to a higher-dimensional linear Hamiltonian, enabling well-defined Berry-phase and phase-rigidity diagnostics. This framework reveals that commonly studied limits, such as the zero-coupling case, correspond to special cross-sections of a broader nonlinear singularity landscape. Our results establish nonlinearity as a fundamental source of topological singularities and provide a general route toward higher-order and unconventional topology beyond linear paradigms.

The discovery of high-temperature superconductivity in bilayer nickelate ${\mathrm{La}}_3{\mathrm{Ni}}_2{\mathrm{O}}_7$ necessitates a minimal theoretical model that unifies the superconducting phase with the spin-density-wave (SDW) phase without external pressure or strain. We propose a model where half-filled $d_{z^2}$ local moments interact with itinerant $d_{x^2-y^2}$ electrons via strong Hund's coupling $J_H$, which reduces to a bilayer type-II $t\text{−}J$ model in the large $J_H$ limit. Using infinite density-matrix renormalization-group calculations on a $L_y=4,L_z=2$ cylinder, where $L_y$ is the system size along the $y$ direction and $L_z=2$ corresponds to the two layers of ${\mathrm{La}}_3{\mathrm{Ni}}_2{\mathrm{O}}_7$, we demonstrate that the competition between double-exchange ferromagnetism and in-plane superexchange generates period-4 stripelike SDW order—a feature absent in the one-orbital $t\text{−}J$ model with only the $d_{x^2-y^2}$ orbital. Furthermore, increasing the interlayer exchange coupling suppresses magnetic order and stabilizes interlayer $s$-wave superconductivity. These results identify the type-II $t\text{−}J$ model as a minimal framework for capturing the interplay of magnetism and superconductivity in bilayer nickelates.

Rare-earth orthovanadates ($R{\mathrm{VO}}_3$), particularly ${\mathrm{GdVO}}_3$, exhibit emergent functional properties due to the strong interplay of spin, orbital, and lattice degrees of freedom. However, synthesizing ${\mathrm{GdVO}}_3$ not only requires a relatively challenging ${\mathrm{H}}_2/{\mathrm{N}}_2$ environment at high temperature, but also its electronic and magnetic structure remains to be clearly resolved. Here, we demonstrate an easily accessible solid-state synthesis route to prepare phase-pure ${\mathrm{GdVO}}_3$ samples in high-vacuum sealed quartz tubes. Thereby, we elucidated the temperature-dependent structural and magnetic phases by combining several experimental techniques along with first-principles calculations. We observe two distinct antiferromagnetic transitions: one due to the Gd-sublattice at $\sim 9$ K (associated with a small temperature hysteresis $\sim 1.4$ K, confirming its first-order nature), and another due to the V-sublattices at $\sim 120$ K. ${\mathrm{GdVO}}_3$ is found to exhibit a large magnetocaloric effect, with a maximum magnetic entropy change of $\approx 28$ J ${\mathrm{kg}}^{-1} {\mathrm{K}}^{-1}$ ($H$ = 5 T) at the Gd-sublattice ordering temperature. It is worth noting that this value is significantly higher than those reported for bulk rare-earth orthovanadates and manganates. Interestingly, a first-order magnetic-field-driven metamagnetic transition below $\sim 8$ K leads to a sign reversal in the magnetic entropy change from inverse to conventional magnetocaloric effect for magnetic fields beyond $\sim$ 2.5 T. Importantly, the large magnetocaloric effect around 9 K originates due to the enhancement of magnetic susceptibility as temperature decreases toward 9 K.

Record-high critical temperatures ($T_{\mathrm{c}}$) of elemental superconductors have been rapidly updated under extreme pressures, yet typically only above the megabar regime. Preserving such high $T_{\mathrm{c}}$ at lower pressures remains a fundamental challenge. Here, we demonstrate that strategic alloying of Ti with controlled amounts of Al yields a family of Ti-Al intermetallics with ω-Ti-derived topological motifs that can be quenched to ambient pressure with substantially higher $T_{\mathrm{c}}\text{s}$. In particular, $\mathrm{T}{\mathrm{i}}_2\mathrm{Al}$ reaches an ambient-pressure $T_{\mathrm{c}}$ of 12.6 K, more than 30 times that of pure Ti. This enhancement originates from motif-preserving substitution: at low Al content, Al acts like hole doping, shifting the Fermi level toward a high density-of-states region, whereas at higher Al content, the weakened interlayer Ti-Ti metallic bonding drives significant softening of three in-plane Ti phonon modes, leading to enhanced electron-phonon coupling. This substitution strategy, which retains a key structural framework while tuning carrier concentration and lattice dynamics, may provide a transferable design paradigm not only for superconductors but also for other functional materials whose properties are governed by specific topological motifs.

We theoretically investigate the charge transport in a normal metal/normal metal/superconductor junction based on semi-Dirac materials. It is shown that off-resonant circularly polarized light applied to the central normal region induces an additional phase for the backreflected states. This light-induced phase depends on the electron's transverse momenta and becomes coherent via multiple reflections, leading to a transversely asymmetric Andreev reflection, which in turn produces a tunneling Hall effect. Both the longitudinal and transverse conductances are obtained within the nonequilibrium Green's function formalism. While the longitudinal conductance is insensitive to the light handedness and only acquires a finite phase shift with varying intensity, the transverse conductance reverses sign upon switching the handedness, indicating the reversal of the tunneling Hall current. Our results establish a phase-coherence mechanism for generating tunneling Hall currents in superconducting tunnel junctions, suggesting potential applications in superconducting electronics.

We numerically investigate the nonlinear dynamics of a two-dimensional exciton-polariton quantum fluid coherently driven by two counterpropagating laser beams. Using an exciton-photon coupled driven-dissipative Gross-Pitaevskii framework, we identify four distinct regimes—that we label as linear, solitonic, turbulent, and superfluid—emerging from the interplay between pump strength, laser detuning, and injected momentum, which together control the balance between kinetic and interaction energies in the quantum fluid. The different regimes are characterized through real-space and momentum-space observables, as well as through the temporal first-order coherence function. We show that the turbulent regime occupies a well-defined and extended region of parameter space, marked by spontaneous vortex nucleation due to the snake-instability process, and a pronounced reduction of temporal coherence, providing a clear signature of nonstationary dynamics. By constructing quantitative phase diagrams, we delineate the transitions between the various regimes and identify multiple pathways connecting the different behaviors. Finally, we demonstrate that the turbulent regime persists over experimentally realistic parameter ranges compatible with state-of-the-art GaAs-based microcavity platforms, establishing counterpropagating polariton flows as a robust and versatile setting for the study of driven-dissipative quantum turbulence in two dimensions.

The phase stability, crystal structure, and melting of Nb have been examined under high pressure shock compression to 365 GPa using ultrafast in situ x-ray diffraction measurements on two x-ray free electron laser facilities. On compression, Nb remains stable in the bcc phase up to 220 GPa, with coexistence of bcc-Nb and liquid from 249 to 298 GPa, and complete melting at 301 GPa, with melt identified by diffuse liquid diffraction. Melting initiates at higher pressure than expected based on theoretical predictions, and the data consistently excludes the presence of other suggested phases of Nb at these pressures, including Pnma and hcp, thereby resolving the long-standing structural discrepancy. Singh-type strength analysis provides experimental evidence for a change in sign of the elastic anisotropy parameter at 121 GPa, consistent with the previously reported heat-induced hardening to heat-induced softening transition in Nb.

We theoretically study angle-resolved magnetoresistance under rotated magnetic field in the normal state of a spin-triplet superconductor ${\mathrm{UTe}}_2$. The Wannier model derived from a $\mathrm{GGA}+U$ calculation shows quasi-two-dimensional Fermi surfaces with warping in the $k_z$ direction, consistent with quantum oscillation measurements in the high magnetic field regime. Solving the semiclassical Boltzmann equation, we show that the Fermi surface geometry gives rise to oscillations in the magnetoresistance when the field is tilted from the $c$ axis toward the $a$ or $b$ axis. By assuming a band-dependent relaxation time, the calculated angle-resolved magnetoresistance is in good agreement with the recent transport experiment. This is direct evidence for the warped Fermi surface revealed by ordinary intraband transport. It suggests that the hole band with long relaxation time dominates electron transport. The field-angle dependence of the Hall resistivity is calculated for further experimental verification.