The scattering of electrons from chiral spin textures such as skyrmions is an emerging research area due to its richness in topological quantum transport, which is significant for spintronic devices. We study the dynamical process of scattering of spin-$\frac{1}{2}$ particles in the form of Gaussian wave packets from skyrmions with the aid of the nonrelativistic time-dependent Schrödinger equation. The scattering cross section shows a rich angular dependence and is deterministically influenced by the iterative flipping of the spin state inside the skyrmion. The latter leads to a set of nontrivial outcomes which include finite transmission and reflection probabilities irrespective of interaction strength, the formation of secondary wave fronts associated with back-converted spin components, and a long-lived quasibound state at the scattering center. In addition to the rich and intriguing physics, the numerical recipe developed here can be easily adopted for any arbitrary spin texture, which will provide a playground to explore tunable spin transport.

We report the intrinsic anomalous Hall effect of ${\mathrm{NdCrGe}}_3$ single crystals, which is a hexagonal ferromagnet metal with a one-dimensional crystal structure. The ${\mathrm{NdCrGe}}_3$ undergoes multimagnetic transitions with a ferromagnetic transition at $T_C\sim 101$ K and a spin reorientation transition at $\sim 55$ K. The Hall effect indicates that the dominant charge carriers shift from electrons to holes near $T_C$. Large anomalous Hall conductivity $\sim 681.8$ (600.3) ${\mathrm{\Omega }}^{-1} {\mathrm{cm}}^{-1}$ for $H//ab$ ($H//c$) is observed, consistent with the theoretically anticipated value derived from the intrinsic Berry-curvature mechanism. The linear scaling relationships observed between the anomalous Hall resistivity and the longitudinal resistivity offer strong and convincing evidence indicating that the intrinsic Karplus-Luttinger mechanism, rather than extrinsic side-jump and skew-scattering mechanisms, assumes a dominant position in the anomalous Hall effect. The distinctive crystal structure, unconventional complex magnetic interactions, and the observed intrinsic anomalous Hall effect could make ${\mathrm{NdCrGe}}_3$ as a promising candidate for future electronic devices.

We develop a self-consistent microscopic framework beyond mean-field theory for monolayer cuprate superconductivity. It couples fermionic quasiparticles with collective phase dynamics to treat the gap and superfluid stiffness. The phase sector explicitly incorporates both smooth bosonic Nambu-Goldstone phase fluctuations, renormalized by long-range Coulomb interactions, and topological BKT-type vortex-antivortex fluctuations. The required input is the correlated single-particle spectral function, enabling direct interfacing with Hubbard-type models. The theory provides access to key superconducting observables, including $T$-dependent gap and phase stiffness, gap-closing temperature $T_{\mathrm{os}}$, and transition temperature $T_c$, across wide ranges of doping. Using a solvable interaction model as input, our simulations reveal several important features consistent with experimental observations in cuprate superconductors: a $d$-wave superconducting dome in $T\text{−}p$ phase diagram with a shoulderlike anomaly in underdoped regime, a pronounced separation between $T_c$ and $T_{\mathrm{os}}$ signaling preformed Cooper pairing, a finite uncondensed normal component persisting even at $T=0$, and the onset temperature $T_{\mathrm{on},\mathrm{vortex}}$ of vortex signals, offering a consistent understanding of how strong correlations and phase fluctuations cooperate to shape high-$T_c$ superconductivity.

In this work, we study the correlation between entanglement and the negative sign problem in quantum Monte Carlo for the simulation of low-dimensional strongly correlated quantum many-body systems. Entanglement entropy characterizes the difficulty of many-body simulations with tensor network state related methods, while the average sign measures the difficulty in many-body simulations for a variety of quantum Monte Carlo methods. Although there exist cases where one type of method works better than the other, it is desirable to find the possible correlation between entanglement and average sign for general hard strongly correlated systems regarding computational complexity. We take the doped two-dimensional Hubbard model as an example and numerically calculate the doping evolution of both the entanglement in the ground state with Density Matrix Renormalization Group and the average sign in the Auxiliary Field Quantum Monte Carlo simulation at low temperatures. The results show that they are indeed correlated. The entanglement entropy (average sign) shows a peak (dip) around $20\%$ doping, indicating that it is a difficult region for both methods. The vicinity of $20\%$ doping is also the most intriguing region in both the Hubbard model and cuprate high-$T_c$ superconductors where competing states with close energy intertwine with each other. Recognizing the correlation between entanglement and average sign provides insights into our understanding of the difficulty in the simulation of strongly correlated quantum many-body systems.

In quantum optics and condensed matter physics, non-Hermitian phenomena are often studied under the assumption of an open physical system. However, there are many examples of intrinsically non-Hermitian, though often $\mathcal{PT}$-symmetric systems, which do not necessarily need to be characterized as open, where one usually speaks of gain and loss relative to an underlying environment. A particularly intriguing example with experimental consequences in the literature is QCD at finite density. Motivated by the existence of such inherently non-Hermitian systems, here we study the critical behavior of a $U\left(1\right)$-invariant Lagrangian perturbed by a complex, $\mathcal{PT}$-symmetric $Z_4$ anisotropy. We find real critical exponents both in the region of unbroken and broken $\mathcal{PT}$ symmetry. In the former the coupling constants for fixed points or lines are real, whereas in the latter they become complex. Importantly, the most stable fixed point corresponds to the flow at large distances towards an effectively Hermitian $U\left(1\right)$ symmetric system. This constitutes an example where both the $U\left(1\right)$ and the Hermitian character are emergent features of the theory. This tells us about the importance and physical meaning of some non-Hermitian systems beyond interpretations involving gain and loss.

As an exclusive feature of a non-Hermitian system, the existence of exceptional points (EPs) depends not only on the details of the Hamiltonian but also on the particle-number filling and the particle statistics. In this paper, we study many-particle EPs in a Bose-Hubbard chain with two end-site resonant imaginary potentials. Starting from a single-particle coalescing eigenstate, we construct $n$-particle condensate eigenstates for the cases with zero and infinite $U$. Compared with the free bosonic case, where the $n$-particle condensate eigenstate is an ${(n+1)}^{\mathrm{th}}$-order coalescing state, the hard-core boson counterpart is a second-order coalescing state for odd $n$, while it is not for even $n$. The difference in particle-number parity results in distinct quenching dynamics of the condensate states, highlighting the role of parity in system behavior. Our finding may stimulate research on the dynamic sensitivity to particle-number parity.

The zero-phonon lines, phonon sidebands and the dynamics of optically induced spin polarization of the neutral divacancies ${\left({\mathrm{V}}_{\mathrm{Si}}{\mathrm{V}}_{\mathrm{C}}\right)}^{\circ }$ in $4H\text{−}\mathrm{SiC}$ have been investigated by EPR spectroscopy. Via in-situ resonant optical excitation at $T=4\mathrm{K}$ the zero phonon lines (ZPL) between the ${}^3{\mathrm{A}}_2$ groundstate and the ${}^3\mathrm{E}$ excited states and their absorption phonon side bands (PSB) have been accurately determined for each of the four ${\mathrm{VV}}^{\circ }$ centers (hh, kk, kh, hk) from the spectral dependence of the EPR line intensity. Their values, respectively 1130.7 nm (hh), 1129 nm (kk), 1107.5 nm (kh) and 1077.3 nm (hk) are in good agreement with previous PL studies and with theoretical predictions. Decomposition of the phonon sidebands of the basal VV centers reveals a coupling with phonons of 24, 36, and 47.5 meV $\left({\mathrm{V}}_{\mathrm{kh}}\right)$ and 11.5, and 18.6 meV $\left({\mathrm{V}}_{\mathrm{hk}}\right)$. The low-temperature optical excitation of the ${\mathrm{VV}}^{\circ }$ centers gives rise to a 100% ground-state spin polarization which persists at $T=4$ K for hundreds of seconds, when the excitation is switched off. Contrary to the case of VV centers in $n$-type nitrogen doped $4H\text{−}\mathrm{SiC}$, the VV centers in $p$-type doped 4H-SiC do not show any charge-state instability under optical excitation.

Recently, various Hall effects in different tunneling junctions have attracted many researchers because of their significant physical properties and potential device applications. Here, we investigate three types of tunneling Hall effects in a $1T^{\prime }\text{−}{\mathrm{MoS}}_2$-based $n\text{−}p\text{−}n$ junction modulated by a vertical electric field and a circularly polarized off-resonant light field. At first, the tunneling valley Hall effect is found without any external fields. Then, the tunneling spin-valley locking Hall effect appears by tuning the vertical electric field. Finally, the tunneling spin-valley polarized Hall effect exists through the competition between an electric field and a circularly polarized off-resonant light field. All the tunneling Hall effects above arise from the tilted and anisotropic band structure of monolayer $1T^{\prime }\text{−}{\mathrm{MoS}}_2$. We further establish a formula, named purity, to characterize the degree of perfection of these tunneling Hall effects. Our work provides an approach to manipulate the spin- and valley-related tunneling Hall effects without relying on Berry curvature, holding promise for applications in both spintronics and valleytronics.

In this work, we numerically investigate linear thermal noise in a four-terminal system with a finite Berry curvature dipole (BCD) using the nonequilibrium Green's function formalism. By comparing with the semiclassical results for bulk systems, we establish a one-to-one correspondence between terminal-resolved linear noise in multiterminal systems and direction-resolved noise in bulk transport. Specifically, the autocorrelation function scales as $2k_{B}T$ when the driving field is perpendicular to the BCD and vanishes when they are parallel, whereas the cross-correlation scales as $k_{B}T$. Both the autocorrelation and cross-correlation functions exhibit pronounced peaks near the band edges, consistent with BCD-induced features. In addition, the linear thermal noise increases approximately linearly with $T$ at low temperatures and is suppressed by the dephasing effect at high temperatures. Our work bridges semiclassical bulk theory and quantum multiterminal theory for linear thermal noise, highlighting the symmetry (geometry)-selection rule in quantum transport.

Andreev levels localized in a weak link between two superconductors can trap a superconducting quasiparticle. If there is a spin-orbit coupling in the link, the spin of the quasiparticle couples to the Josephson current. This effect can be leveraged to control and read out the spin of the quasiparticle, thus using it as a qubit. One of the factors limiting the performance of such an Andreev spin qubit is spin relaxation. Here, we theoretically demonstrate that the relaxation lifetime can be enhanced by utilizing the coupling between the Andreev spin and the supercurrent in a transmon circuit. The coupling ensures that the flip of the quasiparticle spin can only happen if it is accompanied by the excitation of multiple plasmons, as dictated by the Franck-Condon principle. This blocks spin relaxation at temperatures small compared to plasmon energy.

We investigate quantum noise in a mesoscopic quantum dot serving as a realization of the charged Sachdev-Ye-Kitaev (SYK) model weakly coupled to a fermionic lead via a tunnel contact. We find noise signatures under voltage and temperature biases that can serve as clear markers of the SYK physics in experiments with related setups. We develop a linear response theory that treats all types of noise on the same footing and generalizes a concept of transport coefficients for charge and heat currents, as well as relations between them, to equilibrium noise power. Within this theory, we find characteristic scaling of the noise coefficients with temperature in all regimes that can be relevant for experimental realizations of the SYK dots, find a set of universal constants, with their values being unique to the SYK physics, that connect these coefficients, and characterize noise manifestations of the Coulomb blockade. Beyond SYK systems, these results may serve as a general framework for identification of non-Fermi-liquid signatures in mesoscopic transport and provide additional observables for experiments on thermoelectric phenomena.

We report on ultrasonic measurements of the rare-earth altermagnet ${\mathrm{TbPt}}_6{\mathrm{Al}}_3$ in which the Tb magnetic moments in a honeycomb lattice form a collinear antiferromagnetic structure below $T_{\mathrm{N}}=3.4\mathrm{K}$. All elastic moduli show a distinct downward peak at $T_{\mathrm{Q}}=1.6\mathrm{K}$, suggesting an additional phase transition. The transverse moduli $C_{44}$ and $C_{66}$ exhibit significant softening toward $T_{\mathrm{Q}}$, accompanied by ultrasound attenuation. Crystal field analysis of the temperature dependences of elastic moduli reveals that the elastic softening arises from quadrupole-mediated interactions of the ground non-Kramers doublet of the Tb ions. The field-temperature phase diagram in a magnetic field applied along [001] shows an increase in $T_{\mathrm{Q}}$ with increasing field up to 0.8 T. Our crystal field model with the mean-field approximation displays spontaneous occurrence of an expectation value of electric quadrupole at $T_{\mathrm{Q}}$. The agreement between our experimental and calculated results suggests quadrupolar ordering in an altermagnetic ordered state.

The Rashba spin-orbit coupling (SOC) is a well-known mechanism for the spin-charge interconversion via the inverse and direct spin galvanic effects. The lack of a full inversion symmetry allows the coupling of the charge current and spin density. In this paper we investigate this phenomenon when the in-plane rotational symmetry is lowered to the $C_{2v}$ and $C_{3v}$ symmetry groups, whereby the electron spectrum becomes anisotropic. We find that in the $C_{2v}$ case, depending on the ratio between the Rashba SOC strengths along the principal axes, the nonequilibrium spin density deviates notably from the ${90}^{\circ }$ rotation, with respect to the applied electric field, which is familiar in the isotropic case. In the $C_{3v}$ case, when a warping cubic in momentum term is present, whereas the standard ${90}^{\circ }$ rotation of the spin density remains, the spin-charge interconversion depends on the intensity of the warping itself. The microscopic theory takes into account disorder including vertex corrections, via both the diagrammatic implementation of the Kubo formula and the quantum kinetic theory. We show that vertex corrections are crucial to capture the details of the inverse spin galvanic effect in contrast to previous treatments based on the constant broadening approximation.

Exploiting quantum measurements is a promising route for the preparation of correlated quantum states. We use methods from large deviation theory to solve this problem exactly for a specific system: the deterministic quantum East circuit with boundary measurements. We show that conditioning on measurement outcomes generates a long-range correlated state, despite typical trajectories being trivial. We derive the channel that optimally realizes the rare measurement trajectories, and establish a formal connection with the Petz recovery (time-reversal) map. We compute one- and two-point correlation functions in the conditioned state, revealing finite two-body correlations at arbitrarily large separations, and an underlying fractal structure, related to the Sierpiński triangle. These results demonstrate explicitly how boundary measurements can be used to control bulk properties of a quantum system.

Charge noise with a power-law spectrum poses a significant challenge to the high-fidelity operation of spin qubits in semiconductor devices. Recently, considerable experimental work characterized this noise using qubits as spectrometers. It apparently arises from a collection of two-level fluctuating electric dipole systems (TLS). This suggests using the data to infer the positions, orientations, and other physical characteristics of the TLS. We identify a fundamental difficulty in this program: the inference of the TLS parameters is strongly undetermined, since the quantity of data is not sufficient to fix them uniquely. We describe two approaches to deal with this situation. The first approach is a qualitative method based on analytic calculations and simulations of small model systems that recognizes certain patterns. The second approach, more appropriate for detailed data analysis, is a Bayesian computation that assigns probabilities to candidate dipole configurations. We propose that the Brier score, a measure of confidence in the probabilities, can be used as a quantitative tool to judge the efficacy of experimental noise-measurement setups. Together, the analytical and computational Bayesian methods constrain, but do not fix, the density, the positions, the orientations, and the strengths of the dipole noise sources.

We investigate a phonon-modulation mechanism for controlling high-order harmonic generation (HHG) in wurtzite ZnO. Lattice distortions along specific phonon eigenvectors break crystal symmetry and reshape the Berry curvature, which in turn affects the direction, strength, and spectral characteristics of the emitted harmonics. To uncover the microscopic origin of this behavior, we systematically elucidate the nonlinear phononics in ZnO, including the mechanisms of phonon excitation and phonon-phonon coupling. Based on this framework, the control of HHG by phonons arises from the combined influence of the phonon vibration direction, the laser-field polarization, and the crystal symmetry. These results open a pathway to symmetry-guided and phonon-mode-engineered control of ultrafast light emission in solids.

We study the one-dimensional $S=1$ XXZ spin model with single-ion anisotropy. It is known that at the transition points between the Haldane and large-$D$ phases, the model exhibits a quantum criticality described by the Gaussian theory, i.e., a conformal field theory with the central charge $c=1$. Using the bosonization approach, we investigate various correlation functions at the phase transition and derive their asymptotic forms. This allows us to clarify their peculiar behavior: the longitudinal (transverse) two-point spin correlation function has components that decay algebraically only in the uniform (staggered) sector. These theoretical predictions are verified by the numerical calculations using the density-matrix renormalization-group method. The effect of weak bond alternation on the critical ground state at the phase transition is also discussed. It is shown that the bond alternation induces the missing power-law components in the correlation functions.

The pursuit of superconductors combining kagomelike features represents a cutting-edge research challenge. Through crystal structure prediction and first-principles calculations, we systematically explore the Mg-P-H ternary system at 200 GPa, identifying two stable phases: kagome-structured ${\mathrm{MgP}}_2{\mathrm{H}}_3$ and hydrogen-clathrate ${\mathrm{MgPH}}_6$. Electron localization function analysis reveals that the kagomelike ${\mathrm{MgP}}_2{\mathrm{H}}_3$ exhibits a hybrid bonding character comprising both covalent and ionic bonds. Electron-phonon coupling calculations reveal a high superconducting critical temperature of 82.93 K in kagomelike ${\mathrm{MgP}}_2{\mathrm{H}}_3$, arising from strong coupling between optical/acoustic phonon modes and electronic states at the Fermi surface composed of $\mathrm{P}-3p$, $\mathrm{Mg}-3p$, and $\mathrm{H}-1s$. This work not only uncovers high-temperature superconducting in the Mg-P-H system but also establishes a theoretical framework for designing kagomelike based superconducting hydrides.

Spin chains with quenched disorder exhibit rich critical behavior, often captured by real-space renormalization group (RSRG) techniques. However, the physics of such systems in the presence of random measurements (i.e., non-Hermitian dephasing) remains largely unexplored. The interplay between measurements and unitary dynamics gives rise to novel phases and phase transitions in monitored quantum systems. In this work, we investigate the disordered XX spin chain subject to stochastic local measurements in the $X$ and $Y$ bases. By mapping the monitored chain to a non-Hermitian spin ladder with complex couplings, we propose an RSRG-for-excited-states (RSRG-X) approach for this open-system setting. Our analysis reveals a new class of strongly disordered fixed points that emerge due to nonunitarity, broadening the landscape of critical phenomena accessible via RSRG.