Magnons have attracted significant attention due to their unique emergent properties, including ultra-low-energy dissipation and nonvolatility, which have greatly enriched the field of spintronics. While magnon spin currents have been extensively explored across various systems, direct magnon-to-charge conversion, and magnon spin currents modulated by ferroelectric polarization, especially in ferromagnetic metal, have received comparatively less attention. Here, we report the direct observation of ferroelectric polarization-controlled interfacial magnons and the room-temperature sign reversal of magnon-to-charge conversion in ferromagnetic-metal/ferroelectric systems. This effect originates from an ultralong-range, magnonic linear magnetoelectric effect and Rashba spin-orbit coupling at the interface. We demonstrate that Co/PMN-PT heterostructures enable highly efficient, self-contained magnon-to-charge conversion, offering a novel approach for generating and modulating magnon spin currents. Our findings underscore the potential of magnetoelectric systems for ultra-low-energy magnonic devices.

We study the topology of the order parameter in the intermediate phase between the superconducting and time-reversal symmetry-breaking transitions of a $p_x+i{p}_y$ superconductor under strain. The application of in-plane strain reduces the underlying crystal symmetry and lifts the degeneracy of the critical temperature between the $p_x$ and $p_y$ orbitals, resulting in a Dirac cone structure in the thermodynamic phase diagram. When the strain is varied adiabatically along a closed path enclosing the Dirac cone, the order parameter acquires a Berry phase of $\pi$, which originates from a half rotation of the superconducting gap function. This half rotation leaves a topological signature in the superfluid stiffness tensor, making it directly observable through the geometry of vortices and the upper critical field.

Nondemolition protocols use ancilla qubits to identify the fragile quantum state of a qubit without destroying its encoded information, thus playing a crucial role in nondestructive quantum measurements particularly relevant for quantum error correction. However, the multitude of ancilla preparations, information transfers, and ancilla measurements in these protocols create an intrinsic overhead for information processing. Here we consider an Andreev qubit defined in a quantum-dot Josephson junction and show that the macroscopic time-dependent oscillatory supercurrent arising from the quantum interference of the many-body eigenstates, can be used to probe the qubit itself—arbitrarily close to the nondestructive limit—under currently available experimental capabilities. This readout of the arbitrary superposition states of Andreev qubits avoids ancillas altogether and significantly reduces the experimental overhead as no repetitive qubit reinitialization is needed. Our prediction of an ac-like Josephson effect without an applied external voltage, which enables the nondestructive qubit readout, is a unique macroscopic manifestation of the microscopic dynamics of the Andreev quantum state. Our findings should have an unprecedented impact on advancing research and applications involving Andreev dots, thus positioning them as promising qubit contenders for quantum processing and technologies.

The temperature and strain dependences of the optical conductivity spectrum of hexagonal manganese telluride (MnTe) were measured, revealing absorption in the terahertz (THz) region from spin-split bands to acceptor levels. The temperature dependence of the THz absorption peak is consistent with that of a ferromagnetic phase transition, even though MnTe exhibits no net magnetism. The temperature dependence was attributed to a change in the altermagnetic electronic structure. Under negative uniaxial strain, the THz peak shifts to the high-energy side, suggesting spin-splitting bands at energies away from $E_{\mathrm{F}}$, consistent with the theoretical prediction that the spin-splitting angle decreases. The observed behavior of the THz peak clearly shows that MnTe has an altermagnetic electronic structure. Additionally, a Fano-like asymmetric line shape in the optical phonon absorption was observed, possibly originating from interactions with the alternative spin-split bands.

First-order magnetic phase transitions (FOMTs) have garnered extensive interest due to the coupling among lattice, spin, and electron degrees of freedom, which frequently manifests as abrupt magnetization jumps, phase coexistence, and anomalous transport phenomena. In this work, we report the observation of a FOMT in a distorted kagome metal ${\mathrm{Pr}}_3{\mathrm{MnBi}}_5$. Meanwhile, comprehensive measurements of magnetization, specific heat, and electrical transport reveal successive anomalies below 50 K, indicating a complex magnetic landscape. Notably, a pronounced first-order transition occurs at 25 K, as evidenced by the clear discontinuity and thermal hysteresis in both temperature-dependent magnetization and resistivity. Low-temperature x-ray diffraction reveals a volume anomaly across 25 K without a change in crystal symmetry, further confirming the FOMT nature. The magnetic states, transport behavior, and FOMT can be well manipulated by an external magnetic field, which underscores a significant spin-lattice and electron-lattice coupling effect. Furthermore, due to the quasi-one-dimensional geometry, ${\mathrm{Pr}}_3{\mathrm{MnBi}}_5$ exhibits strong magnetic anisotropy with in-plane easy magnetization. A pronounced positive magnetoresistance (68%) is presented in its low-temperature ferromagnetic ground state. These findings establish ${\mathrm{Pr}}_3{\mathrm{MnBi}}_5$ as a compelling distorted kagome platform for investigating the intricate interplay among magnetic anisotropy, lattice geometry, and transport behavior.

We report the magnetic structure of the pseudo-Tsai Tb-Au-Si 1/1 approximant crystal (AC), a periodic crystal where the ${\mathrm{Tb}}^{3+}$ magnetic ions are arranged in a bcc packing as icosahedron nodes plus center decoration. While looking seemingly long ranged in dc magnetometry and neutron diffraction experiments, this crystal shows dynamical magnetic behavior consistent with a spin glass, including aging and memory effects. The relevance of the spin chirality subtended by three noncoplanar magnetic moments, and its order and disorder is discussed. The results are compared to those obtained for the regular Tsai Tb-Au-Si 1/1 AC and binary quasicrystals in order to establish an electronic phase diagram illustrating the boundary between long-ranged and short-ranged order in those systems.

Two-dimensional (2D) ferroelectrics (FEs) with scale-free polarization provide a promising platform for next-generation nanoscale information technologies. Using first-principles calculations, we predict a 2D FE ${\mathrm{Ba}}_2{\mathrm{Sb}}_2{\mathrm{Se}}_4{\mathrm{F}}_2$ monolayer and demonstrate a concrete realization of 2D scale-free ferroelectricity, enabled by the weak coupling between the polar Sb–Se chains on the two surfaces of the monolayer. The unconventional polarization behavior in ${\mathrm{Ba}}_2{\mathrm{Sb}}_2{\mathrm{Se}}_4{\mathrm{F}}_2$ monolayer originates from two Sb–Se polarization chains that are effectively decoupled in both electronic structure and lattice dynamics. This decoupling enables independent dipole switching, such that the macroscopic polarization arises purely from the vectorial superposition of local molecular dipoles, giving rise to a well-defined scale-free FE response. The energy landscape contains multiple FE, antiferroelectric (AFE), and metastable intermediate states connected by low-barrier switching pathways. As a result, the monolayer supports eight reversible polarization states, offering a versatile platform for multilevel applications. Our findings expand the family of scale-free FEs and highlight monolayer ${\mathrm{Ba}}_2{\mathrm{Sb}}_2{\mathrm{Se}}_4{\mathrm{F}}_2$ as a promising candidate for multifunctional FE devices.

We show that the magnetic ground state of the double perovskite ${\mathrm{NdSmNiMnO}}_6$ is jointly controlled by $A$-site (Nd/Sm) mixing, $B$-site (Ni/Mn) ordering, and spin-lattice coupling, with the rare-earth sublattice actively participating in the low-energy magnetic balance. Synchrotron x-ray diffraction (SXRD) and Rietveld refinement establish a monoclinic ($P{2}_1/n$) structure with predominant $B$-site rocksalt order and measurable antisite disorder, while x-ray absorption near-edge structure identifies ${\mathrm{Ni}}^{2+}$ and ${\mathrm{Mn}}^{4+}$ valence states. Magnetometry reveals a ferromagnetic (FM) transition at $T_C\approx 175\mathrm{K}$ driven by ${\mathrm{Ni}}^{2+}\text{-O-}{\mathrm{Mn}}^{4+}$ exchange, followed at lower temperature by a ferrimagneticlike (FiM) regime when the $3d$ and $4f$ sublattices are magnetically ordered. Concomitantly, Raman modes exhibit anomalous hardening below $T_C$ and the refined SXRD lattice parameters display clear anomalies at the magnetic transitions, evidencing pronounced magnetoelastic coupling. Spin-polarized density functional theory captures this competition, yielding nearly degenerate FiM and FM solutions ($\mathrm{\Delta }E\approx 2\mathrm{meV}$ per 20-atom cell) and indicating that coupling of the rare-earth sublattice to the Ni-O-Mn network sets the energy balance. The ferrimagnetic solution carries local moments of $\sim 1.6 {\mu }_{\mathrm{B}}$ on Ni and $\sim 3.0 {\mu }_{\mathrm{B}}$ on Mn and remains insulating, with a gap of 1.6–1.7 eV. With spin-orbit coupling (SOC), the projected ${\mathrm{Sm}}^{3+}$ spin moment is strongly reduced (4.93 to 0.3 ${\mu }_{\mathrm{B}}$), reflecting SOC-driven quenching of the Sm spin polarization, while the gap is nearly unchanged, indicating that the electronic structure is primarily stabilized by Ni/Mn $3d$–O $2p$ hybridization. Our results provide a quantitative framework to disentangle rare-earth $A$-site magnetism from Ni-O-Mn exchange and to rationalize magnetoelastic responses in $A$-site-disordered double perovskites near competing magnetic states.

Structural and dynamic correlations in the ground state of the one-dimensional Fermi one-component plasma are studied using quantum Monte Carlo simulations. Results are presented for the pair correlation function, the static structure factor, the one-particle density matrix, and the momentum distribution for the cases of full, partial, and no polarization. Within the precision of the calculation, the results conform to the fundamental scaling prediction of the Tomonaga-Luttinger liquid theory. Evidence of density correlations slowly decaying with distance is reported, with the concurrent emergence of quasicrystalline order even in the weakly correlated regime. Effects of quantum statistics in the momentum distribution are discussed.

Nonlinear responses in transport phenomena have attracted significant attention because they can arise even when linear responses are forbidden by symmetry, with the quantum geometry of Bloch wave functions playing an essential role. While such effects have been extensively studied in electric transport, similar quantum-geometric mechanisms are also expected to govern nonlinear thermal transport. In particular, thermal responses are crucial in bosonic systems such as magnons and phonons, which are charge-neutral quasiparticles. However, a consistent theoretical description of nonlinear thermal transport remains challenging because of the difficulty in treating energy magnetization in higher-order responses with Luttinger's gravitational potential method. Here, we formulate the intrinsic nonlinear thermal conductivity of bosonic systems using a quantum kinetic equation approach that avoids Luttinger's method and naturally incorporates contributions from energy magnetization. We identify three distinct contributions to the nonlinear thermal conductivity: two expressed in terms of quantum-geometric quantities, namely the quantum metric and the thermal Berry-connection polarizability (TBCP), and a third determined solely by the band dispersions. Applying our formalism to a specific quantum spin model within linear spin-wave theory, we show that the TBCP term dominates the nonlinear thermal Hall effect in the absence of threefold symmetry. Our results differ quantitatively from those obtained using semiclassical theory, thereby highlighting the importance of quantum corrections beyond the semiclassical picture. These findings establish a general framework for intrinsic nonlinear thermal responses in bosonic systems and reveal quantum-geometric mechanisms underlying thermal transport beyond linear response theory.

Path-integral techniques are a powerful tool for obtaining exact solutions for the non-Markovian dynamics of open quantum systems. However, the exponential scaling of the tensor size with the quantum memory length limits their applicability to systems with long memory times. Here we provide a general optimization of tensor multiplication schemes for systems with pair correlations and finite memory times. This optimization effectively reduces the tensor sizes by using a matrix representation of tensors combined with singular value decomposition to filter out negligible contributions. This approach dramatically reduces both computational time and memory usage of the traditional tensor-multiplication schemes. While more memory-efficient representations exist, this approach enables a consistent extrapolation scheme for the rapid estimation of the exact value. As a demonstration, we apply it to the Trotter decomposition with linked cluster expansion technique and use it to investigate a quantum dot-microcavity system at large coupling strengths. We also apply the optimization in a case where the memory time is very long—specifically in a system containing two spatially separated quantum dots in a common phonon bath.

We investigate thermal and nonlocal electrical transport in four-terminal Josephson junctions formed by a normal region coupled to two transverse chiral superconducting leads, supporting phases characterized by Chern numbers $\mathcal{C}=0,1$, and 2. For $\mathcal{C}=1$, we identify the conditions under which a single chiral Majorana mode, with equal superposition of electrons and holes, produces a robust half-integer quantized thermal conductance and a zero nonlocal electrical conductance. Thermal conductance quantization occurs near a superconducting phase difference $\pi$, but only in the low-doping regime of the central region and in the intermediate- to long-junction limits. At finite Zeeman fields, the thermal response broadly follows the topology of the isolated superconducting leads for the $C=1$ phase while, in the $\mathcal{C}=2$ phase, the thermal conductance generally deviates from quantization, depending on the momentum-space location of the Majorana modes. Our results establish clear criteria for probing chiral Majorana modes in Josephson junctions and highlight the essential role of momentum-space structure, finite-size geometry, and sample parameters in thermal transport.

Closed chaotic quantum systems relax after a quench from a typical initial state into a Gibbs ensemble. At late times, the relaxation behavior is determined by their conservation laws and hydrodynamics. For specific initial states, this picture can break down. As a result, there exist pairs of initial states which asymptotically evolve to the same ensemble, yet exhibit drastically different relaxation. We show in two chaotic spin chains how this enables the quantum strong Mpemba effect: A system initially closer to equilibrium relaxes qualitatively slower than one that starts farther away, despite both approaching the same final state.

Functionalized conjugated polymers are promising materials for electromechanical applications due to predicted giant piezoelectricity arising from anomalously large dynamical effective charges combined with an enhanced response near a dimerization phase transition. In this work, we further establish their potential by assessing the robustness of the piezoelectric response of a prototypical polymer against potentially detrimental quantum ionic fluctuations. We use the stochastic self-consistent harmonic approximation with a Rice-Mele diatomic chain model, parametrized to reproduce hybrid-functional first-principles calculations. Despite quantum fluctuations in the bond length reaching magnitudes comparable to the average value, the strong piezoelectric response persists. The topological enhancement of the effective charges remains robust and is even enhanced by about 20% thanks to a quantum-induced shrinking of the electronic gap. The piezoelectric coefficient remains dominated by the internal relaxation and retains a morphotropic-like character, reaching maximum values near the phase boundary renormalized by quantum fluctuations. Our results contribute to pushing forward functionalized conjugated polymers as a promising platform for high-performance organic piezoelectrics.

Transition metal dichalcogenide (TMD) lateral heterostructures are a promising realization of atomically thin p-n junctions and optical devices. While experimental heterostructures show interfacial disorder across various length scales, the computational cost of first-principles modeling restricts analysis to near-pristine interfaces. We bridge this gap by combining a machine-learned tight-binding model with the recursive Green's functions technique for over 1300 explicitly disordered $\mathrm{Mo}{\mathrm{S}}_2\text{−}\mathrm{W}{\mathrm{S}}_2$ interface widths up to 40 nm. Using an information theoretic approach, we define an effective disorder width, $w_{\mathrm{eff}}$, to quantify the extent of on-lattice intermixing disorder. For a small disorder width, $w_{\mathrm{eff}}\le 6$ nm, we observe improvement in conduction band transparency compared to the pristine interfaces. Additionally, at higher energies in the conduction band, we find a transparency increase up to $3.66\times$, with improvements for $w_{\mathrm{eff}}$ up to 20 nm. We attribute this improvement to the opening of nonspecular transmission channels that relax transverse momentum conservation, enabling tunneling between otherwise mismatched valleys. Our results suggest that moderate interfacial intermixing can be used to optimize transmission across lateral interfaces.

We investigate the dynamics of the periodically driven PXP model and show how the interplay between spectral properties and initial states gives rise to distinct dynamical regimes, revealed by the pattern of the revivals. For Néel-ordered initial states, revivals follow distinct trajectories governed primarily by a dominant quasienergy spacing in the Floquet spectrum. Initial states interpolating between Néel and fully polarized configurations display hybrid dynamics, whose character can be tuned through their overlap with Floquet eigenstates by varying the driving parameters. This tunability also provides different pathways to avoid Floquet thermalization, highlighting how both the initial state and the driving protocol shape long-lived dynamics in driven quantum many-body systems.

The development of a pump-probe spectroscopy scheme to control time- and external field-resolved dynamics of an electron-nuclear spin feedback system in bulk n-GaAs is outlined. Two pump pulses within the repetition rate of a mode-locked laser are optically detuned from the n-GaAs absorption edge to manipulate the Overhauser field produced by the optical Stark effect-induced electron spin rotations. Tunable control over both the strength and direction of the Overhauser field is achieved by arbitrarily adjusting the pump-pump temporal separation, pump polarizations, and pump powers. Unlike the one-pump regime where the Overhauser field depends on and synchronizes to the laser repetition rate, the two-pump scheme provides access to regimes of electron–nuclear spin control that are otherwise inaccessible, thereby enabling finer control over the Overhauser field and subsequent electron-nuclear spin interactions. The accessible regimes of electron-nuclear spin control produced by the outlined two-pump scheme offer a versatile framework for precisely controlling the Stark effect-induced electron-nuclear spin feedback and may be extended to other material systems that optically excite electron and nuclear spin polarization.

Motivated by recent experimental evidence for spin supersolid states in triangular-lattice compounds, we numerically investigate the dynamical properties of magnetic-field-induced phases in the spin-1/2 easy-axis triangular antiferromagnetic Heisenberg model in the presence of magnetic impurities. In both weak- and strong-field spin supersolid states, the gapless Goldstone mode at the $K$ points remains robust against impurities, which is a direct manifestation of spin superfluidity. By contrast, at the same impurity density, impurities induce a splitting of the magnon bands in the conventional magnetic state, the so-called up-up-down state. In addition, the finite superfluid stiffness probed by the twisted phase in the spin supersolid states is consistent with the excitation spectrum. We argue that the excitation spectrum with impurities provides direct spectroscopic evidence for dissipationless spin dynamics in the spin supersolid states, which is experimentally accessible via inelastic neutron scattering.