Motivated by growing evidence for the significance of the third-nearest-neighbor Heisenberg ($J_3$) interaction in candidate Kitaev materials, we investigate the dynamical properties of the Kitaev spin liquid (KSL) under a $J_3$ perturbation, focusing on its spin dynamical structure factor (DSF) and Raman scattering. Within a self-consistent parton mean-field plus random-phase-approximation framework, we find that $J_3$ induces coherent, paramagnonlike collective modes that coexist with a high-energy Majorana continuum in the spin DSF. The softening of these modes with increasing $|J_3|$ signals a quantum phase transition to magnetic order. Remarkably, magnetic ordering sets in at a common critical $J_3$ for both ferromagnetic ($K<0$) and antiferromagnetic ($K>0$) Kitaev models, with the resulting ordered states forming exact dual pairs under a four-sublattice duality transformation that maps $(K,J_3)\to (-K,J_3)$. An external magnetic field further softens the preexisting paramagnon modes, thereby enhancing magnetic order. Perturbative Raman calculations show that while the Kitaev-like Raman vertex probes only itinerant matter Majorana fermions, the response from the $J_3$-like vertex features both matter Majoranas and visons. Four-vison excitations produce a sharp peak accompanied by a two-fermion continuum, whereas two-vison excitations yield a continuum closely resembling the single-matter-fermion density of states. These results provide a unified perspective on the dynamical signatures of the $J_3$-perturbed KSL and are helpful for interpreting experimental spectra in candidate Kitaev materials with sizable $J_3$ interactions.

We benchmark constrained-path Monte Carlo (CPMC) on the triangular-lattice Hubbard model for several fillings and $U$ values and show that symmetry-adapted trial wave functions substantially improve quantitative accuracy. Away from half filling, simple free-electron-based trials that preserve the ground state symmetry yield energy deviations $\lesssim 1\%$ from exact diagonalization and density matrix renormalization group results. At half filling, strong frustration in the intermediate to large $U$ regimes necessitates symmetry-projected trials to reach comparable accuracy, where both free-electron and symmetry-broken Hartree-Fock trials incur substantial constraint bias. Since the computational cost of CPMC with symmetry projection scales polynomially with system size, our results motivate its use as a practical route for studying competing ground states in strongly correlated, frustrated systems.

Exactly solvable models of topologically ordered phases with non-Abelian anyons typically require complicated many-body interactions that do not arise naturally. This motivates the “inverse problem” of quantum many-body physics: How to design a microscopic Hamiltonian that realizes a desired topological phase with a given, restricted type of two-body interactions? Here, we address this problem for systems where elementary two-level degrees of freedom couple via simple blockade interactions, a platform motivated by Rydberg atoms. Within this framework, we construct Hamiltonians that realize topological orders described by non-Abelian quantum double models. We analytically prove the existence of topological order in the ground states and present efficient schemes to prepare these states. We also introduce protocols for the controlled adiabatic braiding of anyonic excitations that probe their non-Abelian statistics. Our construction is generic and applies to quantum doubles $\mathcal{D}\left(G\right)$ for arbitrary finite groups $G$. We illustrate braiding for the simplest non-Abelian quantum double $\mathcal{D}\left(S_3\right)$.

Employing first-principles theory and nonadiabatic molecular dynamics simulations, we have systematically reported stability, electronic, optical, photocatalytic, and charge transfer characteristics of Janus PtSSe/BeP heterostructures for water splitting. SePtS/BeP and SPtSe/BeP heterostructures have semiconducting properties ($E_g\sim 0.23–1.18\mathrm{eV}$), low excitonic binding energy ($E_{\mathrm{exb}}\sim 0.31–0.41\mathrm{eV}$), high charge carrier mobility of the order of ${\mu }_e\approx {10}^4\mathrm{c}{\mathrm{m}}^2{\mathrm{V}}^{-1}{\mathrm{s}}^{-1}$ and ${\mu }_h\approx {10}^5\mathrm{c}{\mathrm{m}}^2{\mathrm{V}}^{-1}{\mathrm{s}}^{-1}$, and suitable alignment of bands engulfing water redox potentials. The calculated electron-hole recombination time of 0.09 ps (1.67 ps), which is faster (slower) than the electron transfer time 0.14 ps (0.71 ps) and hole transfer time 0.19 ps (1.01 ps) suggests a $Z$-scheme (type-II) charge transfer mechanism for the SePtS/BeP (SPtSe/BeP) heterostructure. Our study also demonstrates that the heterostructures have enough potential to carry out spontaneous hydrogen evolution reaction and oxygen evolution reaction mechanisms occurring on both surfaces, as it owns zero overpotential (${\eta }_{\mathrm{HER}/\mathrm{OER}}=0$), making it desirable to be a photocatalyst candidate for water splitting. Furthermore, in order to improve the solar-to-hydrogen (STH) efficiency of respective heterostructures, we incorporated a twisting strategy by interlayer rotation at angles of 13.2°, 21.8°, and 27.8°. Having the considerable deviation in band alignments and maintaining the charge transfer mechanism of the pristine heterostructure, the STH efficiency of the PtSSe/BeP heterostructure was enhanced to ∼16%, which suggests the potential use of the respective heterostructure to produce hydrogen. Our results not only offer a strategy for the performance of photocatalytic material to be improved by incorporating twisting layers of heterostructure but also provide a solid photocatalytic mechanism for improved activity.

Majorana zero modes (MZMs), which serve as a key platform for realizing fault-tolerant topological quantum computing, remain challenging in excitation and regulation. In this work, we propose chiral nanoribbon-superconductor hybrids as a platform for realizing multiple MZMs. The hybrid system comprises several intertwined helical chains placed on an $s$-wave superconductor, where a geometric spin-orbit coupling (SOC) varying spatially across helical chains, replaces the traditional Rashba SOC. Using tight-binding models and the Green's function technique, we compute the topological phase diagrams and zero-bias tunneling conductance in the hybrid systems. Numerical results reveal a fragmentation phenomenon occurring in the topological phase as the number of chains increases, and a discrepancy between the topological invariant and the quantized conductance in some specific cases. Furthermore, some overlapping regions of two adjacent topological diagrams exhibit trivial invariants while displaying an increased quantized zero-bias conductance. In addition, Majorana polarization appears and is determined by the chirality of the nanoribbons, and is closely associated with the chirality-induced spin polarization. These findings establish chiral nanoribbon-superstructure hybrids as tunable multichannel systems for regulating multiple MZMs and Majorana polarization.

Entanglement is one of the key measures of quantum correlations present in nanophotonic systems, with promising applications in quantum optics and beyond. Authors of previous studies have shown that the degree of entanglement between two quantum dot (QD) qubits is preserved when a metal nanoparticle (MNP) is used to mediate the interactions between the qubits. In this work, we investigate long-range plasmonic mediation of qubit-qubit entanglement by studying the impact of the number of mediating MNPs on stationary concurrence. Collinear and periodically spaced MNPs that satisfy the weak-coupling approximation are considered. An effective model that enables the derivation of the mediated interactions within the framework of cavity quantum electrodynamics is employed. Under weak driving at the single-particle resonance frequency, the model shows that odd-number arrays are more robust to entanglement decay. We attribute this to strong interqubit dissipative coupling as a result of a hybridized dipole plasmon resonating with the driving frequency in odd-number arrays. These arrays can sustain nonvanishing stationary entanglement beyond an interqubit spacing of 1 µm, opening the possibility of independent spatial optical probing of each QD.

Altermagnets, featuring nonrelativistic spin splitting, have drawn enormous attention due to their intriguing properties. Here, we investigate the effects of shining bicircularly polarized light (BCL) on altermagnets with Rashba spin-orbit coupling. We discover a remarkable tunability of topology, spin textures, and Fermi surfaces of altermagnets by means of BCL illumination, going beyond monochromatic light. We illustrate a cascade of topological phase transitions controllable by BCL and demonstrate how these transitions are reflected in the anomalous Hall response of the altermagnet. Furthermore, we show that the spin textures and Fermi surfaces can be directly tuned by the relative phase of the BCL, stemming from the underlying symmetry changes. Our findings can pave the way for effectively controlling altermagnetic materials with structured light.

Quasiperiodic systems host exotic transport regimes that are distinct from those found in periodic or disordered lattices. In this work, we study quantum transport in the Aubry-André-Harper lattice in a two-terminal setup coupled to zero-temperature reservoirs, where the conductance is evaluated via the nonequilibrium Green’s function method. In the extended phase, we uncover a universal subdiffusive transport when the bath chemical potential aligns with the band edges. Specifically, the typical conductance displays a scaling of ${\mathcal{G}}_{\text{typ}}\sim L^{-2}$ with system size $L$. We attribute this behavior to the emergence of an exceptional point (Jordan normal form) in the transfer matrix in the thermodynamic limit. In the localized phase, the conductance shows exponential decay governed by the Lyapunov exponent. Intriguingly, in the critical phase, we identify pronounced log-periodic oscillations of the conductance as a function of system size, arising from the discrete scale invariance inherent to the singular-continuous spectrum. We further extend our analysis to the generalized Aubry-André-Harper model and provide numerical evidence suggesting that the exact mobility edge resides within a finite spectral gap. This results in a counterintuitive exponential suppression of conductance precisely at the mobility edge. Our work highlights the distinct transport behaviors in quasiperiodic systems and elucidates how they are rigorously dictated by the underlying local spectral structure.

Previous studies have shown that among binary zinc-blende compounds, mercury telluride (HgTe) exhibits exceptionally low lattice thermal conductivity $\left({\kappa }_L\right)$ despite its rather simple crystal structure; however, the underlying heat transfer mechanism remains elusive. Here, we combine self-consistent phonon calculations with the Boltzmann transport equation to investigate the anharmonic lattice dynamics and thermal transport mechanisms in HgTe, with particular emphasis on the role of four-phonon scattering. The results unveil that phonon renormalization arising from both cubic and quartic anharmonicities is indispensable for accurately describing phonon frequencies and lifetimes at finite temperatures. Notably, the renormalization effects exhibit opposite sensitivities to three- and four-phonon scattering processes for heat-carrying acoustic modes, resulting in only a modest net enhancement of ${\kappa }_L$ relative to the harmonic approximation. Moreover, we identify exceptionally strong four-phonon scattering for transverse acoustic phonon modes, driven by large quartic anharmonicity and nearly parallel phonon branches that facilitate four-phonon Fermi resonance. This strong four-phonon effect causes a dramatic reduction in ${\kappa }_L$—by 43% at 100 K—in stark contrast to most known materials, where four-phonon scattering typically becomes relevant only at elevated temperatures. Our study not only elucidates the microscopic mechanisms governing thermal transport in HgTe, but also provides guidance for the rational design of new low-${\kappa }_L$ materials.

We propose a mechanism of supercurrent-induced phonon angular momentum in mixed parity superconductors and $s$-wave superconductors with spin-orbit coupling. We derive analytical expressions of phonon angular momentum induced by the supercurrent by perturbative calculation. The physical interpretation of this effect is also discussed.

We clarify why spin-singlet superconductivity persists in monolayer transition-metal dichalcogenides even in high magnetic fields beyond the Pauli limit. The phenomenon called Ising protection is caused by two magnetically active potentials: a Zeeman field and an Ising spin-orbit interaction. These potentials induce two spin-triplet pairing correlations in a spin-singlet superconductor. One belonging to the odd-frequency symmetry class arises solely from a Zeeman field and always makes the superconducting state unstable. The other belonging to the even-frequency symmetry class arises from the interaction between the two magnetic potentials and eliminates the instability caused by odd-frequency pairs. The presence or absence of such even-frequency spin-triplet pairs explains the anisotropy of the Ising protection. The analytical expression of the superfluid weight enables us to conclude that induced even-frequency spin-triplet Cooper pairs support spin-singlet superconductivity in high Zeeman fields.

Silica $\left({\mathrm{SiO}}_2\right)$ is fundamental to both industrial technology and planetary science, yet the phase relations of its high-pressure polymorphs remain poorly constrained. Here, we develop two machine learning potentials (MLPs) for ${\mathrm{SiO}}_2$ that faithfully represent the strongly constrained and appropriately normed (SCAN) and Perdew-Burke-Ernzerhof revised for solids (PBEsol) exchange-correlation functionals over a wide temperature (1000–10 000 K) and pressure (100–400 GPa) range using deep neural networks. With large-scale two-phase simulations powered by these potentials, we determine the melting curves of seifertite and pyrite-type ${\mathrm{SiO}}_2$ and infer the solid-solid phase boundary between these two phases. The SCAN functional, which captures intermediate-range van der Waals interactions, reproduces structural and thermodynamic properties with high fidelity, predicting melting temperatures 6%–10% higher and a seifertite to pyrite-type transition pressure 22% higher than those of PBEsol. The strongly negative Clapeyron slope (–6.1 MPa/K) of this transition suggests that mantle convection could be highly layered in super-Earth exoplanets, potentially affecting their long-term thermal evolution and habitability.

Trillium lattices, where magnetic ions form a chiral network of corner-sharing triangles, offer a three-dimensional magnetic framework that can host fragile classical spin-liquid states. Herein, we report on the magnetization, specific heat, electron spin resonance (ESR), and muon spin relaxation $\left(\mu \mathrm{SR}\right)$ of ${\mathrm{K}}_2{\mathrm{Fe}}_2\left({\mathrm{MoO}}_4\right){\left({\mathrm{PO}}_4\right)}_2$ single crystals. Magnetization measurements reveal strong antiferromagnetic interactions coexisting with weak magnetic order at $T_{\mathrm{N}}=5.2\mathrm{K}$, as evidenced by a $\lambda$-like anomaly observed in the magnetic susceptibility, a critical enhancement of the muon spin relaxation rate and the wipeout of the ESR signal as the temperature approaches $T_{\mathrm{N}}$. Above $T_{\mathrm{N}}$, two distinct developments of short-range spin correlations are identified at $T_{\mathrm{H}}=34\mathrm{K}$ and $T_{\mathrm{L}}=10\mathrm{K}$, supported by magnetic specific heat anomalies and the temperature dependence of the ESR linewidth and $g$ factor. Upon cooling below $T_{\mathrm{N}}$, an anomaly appears at $T^{*}=3.2\mathrm{K}$ in thermodynamic observables and the muon spin relaxation rate, indicative of spin reorientation driven by residual interactions. Despite the presence of magnetic order, $\mu \mathrm{SR}$ experiments reveal dynamically fluctuating spins persisting even in the ordered state. Moreover, the suppression of $T_{\mathrm{N}}$ under applied magnetic fields $({\mu }_{0}H\ge 2\mathrm{T})$ suggests that ${\mathrm{K}}_2{\mathrm{Fe}}_2\left({\mathrm{MoO}}_4\right){\left({\mathrm{PO}}_4\right)}_2$ constitutes a promising candidate for exploring field-induced spin-liquid behavior in three-dimensionally coupled trillium lattices.

Stimulated by recent experiments on materials representing the realization of the anisotropic Heisenberg spin-$1/2$ model on a triangular lattice (TL), we explore further properties of such a model in the easy-axis regime $\alpha =J_{\perp }/J_z<1$ and the plausibility of finding effective models that capture similar physics. We show that, at finite fields, the magnetization curve as well as the transverse magnetization (superfluid) order parameter $m_{\perp }$ of the TL model are indeed qualitatively reproduced by anisotropic Heisenberg models on the honeycomb or square lattice. At the point of correspondence to the zero-field TL model, however, the bipartite models are qualitatively different, as they remain gapless even at $\alpha \ll 1$ with a small but finite $m_{\perp }>0$. Conversely, we present several additional numerical studies of the full model on the TL which support the appearance of a gap at zero field and $\alpha \ll 1$. The magnetization curve $m\left(h\right)$ and the spin stiffness ${\rho }_s$ indicate a transition/crossover from gappless to gapped regimes at $\alpha \sim {\alpha }^{*}$, with ${\alpha }^{*}\lesssim 0.5$. We also show that deviations from the linear spin-wave theory and the emergence of the gap can be traced back to the strong effective repulsion between magnon excitations, showcasing similarity to strongly correlated systems.

Transport experiments on two-dimensional superconductors often yield direction-dependent transition temperatures, raising the question of whether such a “double-$T_c$” reflects a true thermodynamic splitting or a transport artifact. To establish a baseline, we study a minimal anisotropic phase-only Josephson-junction array in equilibrium and under resistively shunted junction dynamics with fluctuating twist boundary conditions. The equilibrium model exhibits a single Berezinskii-Kosterlitz-Thouless transition. Out of equilibrium, anisotropic Josephson couplings and anisotropic dissipation reshape the linear $R\text{−}T$ curves in a finite-size, finite-current crossover regime, so that curve-shape criteria such as Halperin-Nelson fits and fixed-resistance thresholds yield an apparent double-$T_c$. In contrast, critical-scaling criteria—the universal exponent $\alpha =3$ and dynamic finite-size scaling—remain consistent with the single $T_{\mathrm{BKT}}$. A robust splitting that persists in the nonlinear critical scaling, such as that recently reported at ${\mathrm{KTaO}}_3$ interfaces, therefore, points to physics beyond this clean anisotropic baseline.

The layer-dependent Hamiltonians of parallel-stacked ${\mathrm{MoTe}}_2$ and ${\mathrm{WSe}}_2$ homobilayer moiré materials are topologically nontrivial, both in real space and in momentum space, and have been shown to support integer and fractional quantum anomalous Hall states, as well as antiferromagnetic and superconducting states. Here, we address the interplay between the antiferromagnetic and superconducting states observed in $t{\mathrm{WSe}}_2$ when the Fermi level is close to its $M$-point van Hove singularity and the displacement field is small. We combine density functional theory with path integrals to construct a minimal moiré band model that accounts for lattice relaxation along the $c$axis and perform Hartree-Fock calculations to identify competing charge and spin ordered states. For $t{\mathrm{WSe}}_2$ at $\theta =2.7^{\circ }$ and $\theta =3.{65}^{\circ }$, we find that a layer antiferromagnet, a stripe spin-density wave, and the ferromagnetic Chern insulator are the primary candidates for the ground state at zero displacement field, and argue that antiferromagnetic spin interactions on the next neighbor bond $J_2$ can induce a time-reversal symmetry breaking chiral superconducting state.

Perovskite oxides ${\mathrm{ABO}}_3$ host a rich interplay of charge, spin, lattice, and orbital degrees of freedom, giving rise to diverse quantum phenomena. In low-dimensional ${\mathrm{ABO}}_3$ systems, reduced symmetry can induce exotic quantum effects such as a two-dimensional electron gas and unconventional superconductivity. Using first-principles density-functional theory, tight-binding modeling, and symmetry analysis, we show that ultrathin two-dimensional (2D) ${\mathrm{ABO}}_3$ films—exemplified by ${\mathrm{SrTiO}}_3$—naturally break inversion symmetry, producing a spontaneous out-of-plane bulk photovoltaic (BPV) effect. This differs from previous studies that focused on in-plane BPV current signals and is more applicable and experimentally detectable. Such an effect is highly tunable via thickness, strain, surface termination, crystallographic orientation, and Moiré twisting. These findings are broadly applicable to a wide range of 2D perovskite oxides and other layer-resolved oxides.

The comprehensive description of both the electrical transport along conductive domain walls in lithium niobate single crystals and the charge injection at the interfacing metal electrodes, emerged to be a complex challenge. Recently, a heuristic evaluation allowed to postulate the “$R2D2$” equivalent-circuit model (consisting of two parallel resistor-diode pairs) to appropriately match the dc current-voltage (I-V) characteristics. Here, we carefully revisit the interfacial electrical behavior, i.e., the diode part of the equivalent circuit model, since many more processes beyond the diode-related electron hopping transport (HT) assumed so far, may concurrently occur, such as thermionic emission (TE), Fowler-Nordheim tunneling (FNT), space-charge limited conduction (SCLC), and others. The “$R2D2$” model thus needs to be generalized into an “$R2X2$” circuit model (with $X$ = HT, TE, FNT, SCLC, and others) to fit to the experimental data. Moreover, to check for the best I-V curve fitting to the different theories, we apply a higher-harmonic DW current-contribution analysis, i.e., an ac I-V inspection, that allows us to discriminate between all these possible models with much higher precision than from pure dc I-V curve fitting. Both the ac and dc analysis yield consistent results, finding that the FNT model accounts best for the domain-wall/electrode junctions investigated here.

We study the time-dependent triplet configuration, appearing under nonequilibrium conditions in a nanoscopic junction with two quantum dots (QDs) coupled in series between superconductor and normal metallic lead. We show that, in the situation when both QDs are singly occupied by identical spin electrons, the on-dot electron pairing is suppressed, which substantially affects the subgap charge transport. We investigate processes in which such a configuration can be temporarily encountered, either due to the initial conditions or by imposing the external magnetic field. Our analytical and numerical calculations provide estimations for the temporal scales, characterizing the evolution of the triplet configuration which could be manifested in the time-resolved tunneling measurements. Such nonequilibrium features of the triplet configuration might be relevant to operations on superconducting qubits, in their conventional and/or topological realizations.