This Letter investigates the emergence of corner modes in elastic twisted kagome lattices at a critical twist angle, known as the self-dual point. We show that special types of corner modes exist and they are localized at very specific types of corners independent of the overall shape of the finite lattice. Moreover, these modes appear even in the perturbed lattice at the corners with mirror planes. By exploring their counterparts in electronic systems, we attribute such corner modes to charge accumulation at the boundary, which is confirmed by the plot of charge distribution in a finite lattice.

A general nonlinear theory for the elasticity of prestressed single crystals is presented. Various types of elastic moduli are defined, their importance is determined, and relationships between them are presented. In particular, $\mathit{B}$ moduli are present in the relationship between the Jaumann objective time derivative of the Cauchy stress and deformation rate and are broadly used in computational algorithms in various finite-element codes. Possible applications to simplified linear solutions for complex nonlinear elasticity problems are outlined and illustrated for a superdislocation. The effect of finite rotations is fully taken into account and analyzed. Different types of the bulk and shear moduli under different constraints are defined and connected to the effective properties of polycrystalline aggregates. Expressions for elastic energy and stress-strain relationships for small distortions with respect to a prestressed configuration are derived in detail. Under initial hydrostatic load, general consistency conditions for elastic moduli and compliances are derived that follow from the existence of the generalized tensorial equation of state under hydrostatic loading obtained from a single crystal or polycrystal. It is shown that $\mathit{B}$ moduli can be found from the expression for the Gibbs energy. However, higher order elastic moduli defined from the Gibbs energy do not have any meaning since they do not directly participate in any known equations, like the stress-strain relationships and wave propagation equation. The deviatoric projection of $\mathit{B}$ can also be found from the expression for the elastic energy for isochoric small strain increments, and the missing components of $\mathit{B}$ can be found from the consistency conditions.

We explore the multifractality of the steady state wave function in nonunitary random quantum dynamics in one dimension. We focus on two classes of random systems: the hybrid Clifford circuit model and the nonunitary free fermion dynamics. In the hybrid Clifford model, we map the measurement driven transition to an Anderson localization transition in an effective graph space by using properties of the stabilizer state. We show that the volume law phase with nonzero measurement rate is nonergodic in the graph space and exhibits weak multifractal behavior. We apply the same method to the hybrid Clifford quantum automaton circuit and obtain similar multifractality in the volume law phase. For the nonunitary random free fermion system with a critical steady state, we compute the moments of the probability distribution of the single-particle wave function and demonstrate that it is also weakly multifractal and has strong variations in real space.

The discovery of superconductivity in the heavy-fermion paramagnet ${\mathrm{UTe}}_2$ has attracted a lot of attention, particularly due to the reinforcement of superconductivity near pressure- and magnetic-field-induced magnetic quantum phase transitions. A challenge is now to characterize the effects of combined pressure and magnetic fields applied along variable directions in this strongly anisotropic paramagnet. Here, we present an investigation of the electrical resistivity of ${\mathrm{UTe}}_2$ under pressure up to 3 GPa and pulsed magnetic fields up to 58 T along the hard magnetic crystallographic directions $\mathbf{b}$ and $\mathbf{c}$. We construct three-dimensional phase diagrams and show that, near the critical pressure, a field-enhancement of superconductivity coincides with a boost of the effective mass related to the collapse of metamagnetic and critical fields at the boundaries of the correlated paramagnetic regime and magnetically-ordered phase, respectively. Beyond the critical pressure, field-induced transitions precede the destruction of the magnetically-ordered phase, suggesting an antiferromagnetic nature. By bringing new elements about the interplay between magnetism and superconductivity, our paper appeals for microscopic theories describing the anisotropic properties of ${\mathrm{UTe}}_2$ under pressure and magnetic field.

Anomalous energy transport is a widely investigated character in one-dimensional lattice and both phonons and solitons are candidate energy carriers responsible for the thermal conductivity divergence before their mean-free paths. However, it was long believed the contribution of solitons could be neglected even close to the melting point in a real crystalline solid. In this paper, we show that a crossover of wave-packet dynamics, from a phonon- to a soliton-dominated state, occurs in a quasi-one-dimensional molybdenum disulfide $\left({\mathrm{MoS}}_2\right)$ sheet at high temperatures far below its melting point by nonequilibrium and equilibrium molecular dynamics simulations. Divergent sound speed variation and the corresponding heat capacity peaks are observed in the transition-temperature region that is related to a second-order phase transition. We also find that its anomalous energy transport falls into a universality class with thermal conductivity divergence exponent $\alpha =2/5$ at a finite length scale within 2000 nm when solitons are excited above 600 K, and the scaling relations derived from the Lévy walk of energy carriers is fulfilled as $\alpha =2-1/\gamma =\beta -1$ in the soliton-dominated state above 1800 K. Our results reveal the peculiar solitonlike contribution to thermal conduction at high temperatures in the low-dimensional crystalline solids.

Local excitations as carriers of quantum information spread out in the system in ways governed by the underlying interaction and symmetry. Understanding this phenomenon, also called quantum scrambling, is a prerequisite for employing interacting systems for quantum information processing. The character and direction dependence of quantum scrambling can be inferred from the out-of-time-ordered commutators (OTOCs) containing information on correlation buildup and entanglement spreading. Employing OTOC, we study and quantify the directionality of quantum information propagation in oxide-based helical spin systems hosting a spin-driven ferroelectric order. In these systems, magnetoelectricity permits the spin dynamics and associated information content to be controlled by an electric field coupled to the emergent ferroelectric order. We show that topologically nontrivial quantum phases, such as chiral or helical spin ordering, allow for electric-field controlled anisotropic scrambling and a direction-dependent buildup of quantum correlations. Based on general symmetry considerations, we find that starting from a pure state (e.g., the ground state) or a finite temperature state is essential for observing directional asymmetry in scrambling. In the systematic numerical studies of OTOC on finite-size helical multiferroic chains, we quantify the directional asymmetry of the scrambling and verify the conjectured form of the OTOC around the ballistic wavefront. The obtained direction-dependent butterfly velocity $v_{\mathrm{B}}\left(\mathbf{n}\right)$ provides information on the speed of the ballistic wavefront. In general, our calculations show an early time power-law behavior of OTOC, as expected from an analytic expansion for small times. The long-time behavior of OTOC reveals the importance of (non)integrability of the underlying Hamiltonian as well as the implications of conserved quantities such as the $z$ projection of the total spin. The results point to the potential of spin-driven ferroelectric materials for the use in solid-state-based quantum information processing.

Magnetostatic forward volume spin-waves (MFVSWs) are magnetic moments propagated perpendicular to the film plane and offer reciprocity configurations, which is suitable for spin-wave logic devices with low power consumption. However, owing to the strong shape anisotropy field, magnetic films are easily magnetized in the film plane. Fabrication of thick magnetic films with low Gilbert damping and large perpendicular magnetization anisotropy was an unsolved problem. The promising materials with low damping and easy to modify properties are ${\mathrm{Y}}_3{\mathrm{Fe}}_5{\mathrm{O}}_{12}$-based single-crystal films. High quality $\left({\mathrm{Y}}_{1.26}{\mathrm{Bi}}_{0.18}{\mathrm{Lu}}_{0.96}{\mathrm{Ca}}_{0.6}\right)\left({\mathrm{Fe}}_{4.4}{\mathrm{Ge}}_{0.6}\right){\mathrm{O}}_{12}$ micrometer-thick films with strong anisotropy field up to 1862 Oe, narrow out-of-plane ferromagnetic resonance linewidth as low as 2 Oe, and low Gilbert damping approximately $(7.06\pm 0.15)\times {10}^{-5}$ grow on the gadolinium gallium garnet substrate successfully. The garnet film shows a MFVSW group velocity of 2.25 km/s, relaxation time 50 ns, and decay length up to $115\mu \mathrm{m}$, paving the road towards ultralow power dissipation magnonic devices (microwave devices) based on magnetic insulators.

The superconducting (SC) gap structure appearing in systems with single Fermi surface (FS) is generally described by the single gap function with $s$- or $d$-wave symmetry. The organic superconductor $\lambda$-(BETS)${}_2{\mathrm{GaCl}}_4$ [BETS = (${\mathrm{CH}}_2{)}_2{\mathrm{S}}_2{\mathrm{Se}}_2{\mathrm{C}}_6{\mathrm{Se}}_2{\mathrm{S}}_2$(${\mathrm{CH}}_2{)}_2$] endeavors to examine a novel SC gap structure on the distorted single cylindrical FS. Here, we show an example of the formation of the distorted SC nodal line by using the positive muon spin rotation (${\mu }^{+}\mathrm{SR}$) spectroscopy on $\lambda$-(BETS)${}_2{\mathrm{GaCl}}_4$. Our analysis method of the ${\mu }^{+}\mathrm{SR}$ data reveals that the nodal line has a narrower width than that of the traditional $d$-wave by the steepness factor of 4.6(2.1), and a flat part with the maximum gap exists. We found that the amplitude of the SC gap is $2\mathrm{\Delta }/k_{\text{B}}{T}_c$ = 3.9(2) and the in-plane penetration depth is ${\lambda }_{\text{ac}}$(0) = 560(5) nm. Our present study gives insight into the relation of the FS distortion and the unusual Cooper pair formation mediated by the anisotropic spin fluctuations.

Density functional theory computations are used to predict the electronic structure of Cd-based hybrid organic-inorganic high-$T_C$ ferroelectric perovskites with TMCM-${\mathrm{CdCl}}_3$ being one representative. We report Rashba-Dresselhaus spin splitting in the valence band of these nonmagnetic compounds. Interestingly, we find in computations that the splitting is not necessarily sensitive to the polarization of the material but to the organic molecule itself which opens a way to its chemical tunability through the choice of the molecule. Further chemical tunability of spin splitting is shown to be possible through a substitution of Cl in the ${\mathrm{CdCl}}_3$ chains as the valence band was found to originate from Cl-Cl weekly bonding orbitals. For example, the substitution of Cl with Br in TMCM-${\mathrm{CdCl}}_3$ resulted in a ten times increase of spin splitting. Furthermore, the spin polarization in these materials gives origin to persistent spin textures which are coupled to the polarization direction, and, therefore, can be controlled by the electric field. This is promising for spintronics applications.

We investigate chaotic to integrable transition in two types of hybrid SYK models, which contain both $q=4$ SYK with interaction $J$ and $q=2$ SYK with an interaction $K$ in type-I or ${(q=2)}^2$ SYK with an interaction $\sqrt{K}$ in type-II. These models include hybrid Majorana fermion, complex fermion, and bosonic SYK. For the Majorana fermion case, we discuss both $N$ even and $N$ odd case. We make exact symmetry analysis on the possible symmetry class of both types of hybrid SYK in the 10-fold way by random matrix theory (RMT) and also work out the degeneracy of each energy levels. We introduce a new universal ratio, which is the ratio of the next-nearest-neighbor (NNN) energy level spacing to characterize the RMT. We perform exact diagonalization to evaluate both the known NN ratio and the new NNN ratio, then use both ratios to study chaotic to integrable transitions (CIT) in both types of hybrid SYK models. Some preliminary results on possible quantum analog of Kolmogorov-Arnold-Moser (KAM) theorem and its dual version in the quantum chaotic side are given. We explore some intrinsic connections between the two complementary approaches to quantum chaos: the RMT and the Lyapunov exponent by the $1/N$ expansion in the large $N$ limit at a suitable temperature range. We stress the crucial differences between the quantum phase transition (QPT) characterized by renormalization groups at $N=\infty$, $1/N$ expansions at a finite $N$, and the CIT characterized by the RMT at a finite $N$: the former focus on the ground state and its low-energy excitations (edge states in the Fock space), the latter on excited states (bulk states in the Fock space). We also discuss eigenstate thermalization hypothesis (ETH)'s power on a quantum chaotic bulk state and its inability to encode the edge states. Comments on some previously related works are given. Some future perspectives, especially the failure of the Zamoloddchikov's c-theorem in 1d CFT RG flow are outlined.

Cavities play a fundamental role in optical physics by providing spatiotemporal confinement of energy that facilitates light-matter interactions. They are routinely utilized in a variety of settings, ranging from lasers to spectral filters, to nonlinear wave mixers, and modulators. While their resonant properties make them suitable for sensing, in many applications, like in lasers, it is desired to alleviate their sensitivity in order to make a device more resilient to perturbations. Along these lines there have been several recent reports of using concepts from topological physics in order to design laser arrays that are inherently more robust. Here, we present a class of topological cavities based on Majorana bound states that provide unique scaling features as well as nondegenerate single-mode behaviors. These cavities may lead to a new family of lasers and laser arrays that are robust to defects, fabrication imperfections, and external perturbations.

Embedded in an ohmic environment, the Josephson current peak can transfer part of its weight to finite voltage and the junction becomes resistive. The dissipative environment can even suppress the superconducting effect of the junction via a quantum phase transition occurring when the ohmic resistance $R_s$ exceeds the quantum resistance $R{}_{\text{q}}=h/{\left(2e\right)}^2$. For a topological junction hosting Majorana bound states with a $4\pi$ periodicity of the superconducting phase, the superconductor-insulator phase transition is shifted to $4R{}_{\text{q}}$. We consider a Josephson junction mixing the $2\pi$ and $4\pi$ periodicities shunted by a resistor, with a resistance between $R_q$ and $4R_q$ such that the two periodicities promote competing phases. Starting with a quantum circuit model, we derive the nonmonotonic temperature dependence of its differential resistance resulting from the competition between the two periodicities, the $4\pi$ periodicity dominating at the lowest temperatures. The nonmonotonic behavior is first revealed by straightforward perturbation theory and then substantiated by a fermionization to exactly solvable models when $R_s=2R{}_{\text{q}}$: the model is mapped onto a helical wire coupled to a topological superconductor when the Josephson energy is small and to the Emery-Kivelson line of the two-channel Kondo model in the opposite case. We also settle the compact vs extended phase controversy: introducing a compact phase variable across the junction, associated with a discrete charge, we rigorously prove that it is effectively replaced by an extended phase variable in presence of the environment.

We consider a central-spin battery where $N_b$ central spins serve as battery cells and $N_c$ bath spins serve as charging units. It is shown that the energy stored in the battery that can be extractable is quantified by the ergotropy, and that battery-charger entanglement is quantified via the Von Neumann entropy. By using an exact approach to a one-cell and two-cell battery, our analytical results suggest that, during the charging process, the extractable work slowly increases before the battery-charger entanglement reaches its maximum and then it will rapidly increase when the entanglement begins to decrease. In particular, we rigorously show that there is an inverse relationship between the extractable work and the entanglement at the end of the charging process. Moreover, we investigate different approaches to realize optimal work extraction without wasted energy. Among them a central-spin battery with an unpolarized Dicke state as the charger possesses a universal charging time $\propto 1/N_c$, large extractable work and $\sqrt{N_c}$-improvement of charging power compared with the battery in the Tavis-Cummings limit. The above-mentioned results have also been numerically verified in multicell batteries. Our results pave the way to improve extractable work storage in the central-spin battery and highlight a competitive relation between the extractable work and the battery-charger entanglement.

Motivated by experimental developments introducing the concept of spin-orbit separation, we study the real-space real-time evolution of an excitonic wave packet using a two-orbital Hubbard model in a chain. The exciton is created by exciting an electron from a lower-energy half-filled orbital to a higher-energy empty orbital. We carry out the real-time dynamics of the resulting excitonic wave packet using the time-dependent density matrix renormalization group. We find clear evidence of charge-spin and spin-orbit separation in real space, by tracking the time evolution of local observables. We show that the velocity of the orbiton can be tuned varying the interorbital interactions. We also present a comparative study of the dynamics of a hole in one-orbital and two-orbital Hubbard models. Moreover, we analyze the dynamics of an exciton with spin-flip excitation, where we observe fractionalized spinons induced by Hund's interaction.

Recent experiments have elucidated that novel nonequilibrium states inherent in the so-called hydrodynamic regime are realized in ultrapure metals with sufficiently strong momentum-conserving scattering. In this Letter, we formulate a theory of electron hydrodynamics with broken inversion symmetry under magnetic fields and find that novel terms emerge in hydrodynamic equations which play a crucial role for the realization of the nonreciprocal responses. Specifically, we clarify that there exists a novel type of nonreciprocal collective modes dubbed nonreciprocal surface magnetoplasmons arising from an interplay between magnetic fields and the orbital magnetic moment. We reveal that these nonreciprocal collective modes indeed give rise to the nonreciprocity in magneto-optical responses such as the reflectivity. The physics discussed here will bridge the two important notions magnetoplasmonics and nonreciprocity in electron hydrodynamic materials with inversion symmetry breaking and magnetic fields.

Colloidal semiconductor quantum dots (QDs) are attractive materials that provide unique photophysics of multiple electron-hole pairs (multiexcitons) in strongly quantum confined systems. Multiexciton phenomena such as efficient Auger recombination have been intensively investigated with respect to individual QDs. However, the cooperative nature of QDs, especially in terms of multiexciton coherence, has not been elucidated thus far. Here, we report the observation of the collective enhancement of quantum coherence in coupled QD films. Using a photocurrent quantum interference technique, we find that the multiexciton quantum coherence in coupled QDs is significantly increased compared to the case of isolated QDs. This cooperative effect is induced by the coherent electronic coupling between QDs. Our results clarify the enhancement mechanism in coupled quantum systems and open the door to advanced optoelectronic applications such as coherent amplifiers and frequency upconverters.

${\mathrm{CoNb}}_2{\mathrm{O}}_6$ is a rare realization of the transverse-field Ising model, making it a useful tool for studying both equilibrium and nonequilibrium many-body quantum physics. Despite a large body of work dedicated to characterizing this material, details of the ordered states in the presence of relatively weak transverse fields have not been discussed in detail. Here, we present a detailed study of ${\mathrm{CoNb}}_2{\mathrm{O}}_6$ via ac susceptibility measurements in order to further characterize its low-temperature behavior in the presence of a transverse field. Specifically, we call attention to an unconventional freezing transition in zero field below $T_F=1.2$ K, occurring within the well-known commensurate antiferromagnetic (CAFM) state that onsets at $T_{N2}=1.9$ K. We performed a series of transverse-field quenches into this frozen state, which resulted in a slowly relaxing susceptibility, ${\chi }^{\prime }\left(t\right)$, that followed a logarithmic decay within the time range measured. We discuss the frozen state in the context of the freezing of previously discussed “free” chains arising from domain walls between the four degenerate sublattices of the CAFM state. We also attempted to observe Kibble-Zurek scaling by quenching the transverse field into the frozen state at different rates. This produced a null result; the behavior can be fully explained by coarsening of domains over the time scale of the quenches. The absence of a clear Kibble-Zurek scaling is itself surprising, given the proposed ubiquity of the phenomenon for general second-order phase transitions.

Impurities coupled to superconductors offer a controlled platform to understand the interplay between superconductivity, many-body interactions, and nonequilibrium physics. In the equilibrium situation, local interactions at the impurity induce a transition from the spin-singlet to the spin-doublet ground state, resulting in a supercurrent sign reversal ($0\text{−}\pi$ transition). In this work, we apply the exact time-dependent density matrix renormalization group method to simulate the transient dynamics of such superconducting systems. We also use a perturbative approximation to analyze their properties at longer times. These two methods agree for a wide range of parameters. In a phase-biased situation, the system gets trapped in a metastable state characterized by a lower supercurrent compared to the equilibrium case. We show that local Coulomb interactions do not provide an effective relaxation mechanism for the initially trapped quasiparticles. In contrast, other relaxation mechanisms, such as coupling to a third normal lead, make the impurity spin relax for parameter values corresponding to the equilibrium 0 phase. For parameters corresponding to the equilibrium $\pi$ phase the impurity converges to a spin-polarized stationary state. Similar qualitative behavior is found for a voltage-biased junction, which provides an effective relaxation mechanism for the trapped quasiparticles in the junction.