The application of the eigenstate thermalization hypothesis to non-Hermitian quantum systems has become one of the most important topics in dissipative quantum chaos, recently giving rise to intense debates. The process of thermalization is intricate, involving many time-evolution trajectories in the reduced Hilbert space of the system. By considering two different expansion forms of the density matrices adopted in the biorthogonal and right-state time evolutions, we derive two versions of the Gorini–Kossakowski–Sudarshan–Lindblad (GKSL) master equations describing the non-Hermitian systems coupled to a bosonic heat bath in thermal equilibrium. By solving the equations, we identify a sufficient condition for thermalization under both time evolutions, resulting in Boltzmann biorthogonal and right-eigenstate statistics, respectively. This finding implies that the recently proposed biorthogonal random matrix theory needs an appropriate revision. Moreover, we exemplify the precise dynamics of thermalization and thermodynamic properties with test models.

We propose a simple quantum voting machine using microwave photon qubit encoding, based on a setup comprising multiple microwave cavities and a coupled superconducting flux qutrit. This approach primarily relies on a multi-control single-target quantum phase gate. The scheme offers operational simplicity, requiring only a single step, while ensuring verifiability through the measurement of a single qubit phase information to obtain the voting results. It provides voter anonymity, as the voting outcome is solely tied to the total number of affirmative votes. Our quantum voting machine also has scalability in terms of the number of voters. Additionally, the physical realization of the quantum voting machine is general and not limited to circuit quantum electrodynamics. Quantum voting machine can be implemented as long as the multi-control single-phase quantum phase gate is realized in other physical systems. Numerical simulations indicate the feasibility of this quantum voting machine within the current quantum technology.

This work focuses on the evolution behaviors of ring dark solitons (RDSs) and the following vortices after the collapses of RDSs in spin-1 Bose–Einstein condensates. We find that the weighted average of the initial depths of three components determines the number and motion trajectories of vortex dipoles. For the weighted average of the initial depths below the critical depth, two vortex dipoles form and start moving along the horizontal axis. For the weighted average depth above the critical depth, two or four vortex dipoles form, and all start moving along the vertical axis. For the RDS with weighted average depth at exactly the critical point, four vortex dipoles form, half of the vortex dipoles initiate movement vertically, and the other half initiate movement horizontally. Our conclusion is applicable to the two-component system studied in earlier research, indicating its universality.

Fractional orbital angular momentum (OAM) vortex beams present a promising way to increase the data throughput in optical communication systems. Nevertheless, high-precision recognition of fractional OAM with different propagation distances remains a significant challenge. We develop a convolutional neural network (CNN) method to realize high-resolution recognition of OAM modalities, leveraging asymmetric Bessel beams imbued with fractional OAM. Experimental results prove that our method achieves a recognition accuracy exceeding 94.3% for OAM modes, with an interval of 0.05, and maintains a high recognition accuracy above 92% across varying propagation distances. The findings of our research will be poised to significantly contribute to the deployment of fractional OAM beams within the domain of optical communications.

Quantum nonreciprocity, such as nonreciprocal photon blockade, has attracted a great deal of attention due to its unique applications in quantum information processing. Its implementation primarily relies on rotating nonlinear systems, based on the Sagnac effect. Here, we propose an all-optical approach to achieve nonreciprocal photon blockade in an on-chip microring resonator coupled to a V-type Rb atom, which arises from the Zeeman splittings of the atomic hyperfine sublevels induced by the fictitious magnetic field of a circularly polarized control laser. The system manifests single-photon blockade or multi-photon tunneling when driven from opposite directions. This nonreciprocity results from the directional detunings between the countercirculating probe fields and the V-type atom, which does not require the mechanical rotation and facilitates integration. Our work opens up a new route to achieve on-chip integrable quantum nonreciprocity, enabling applications in chiral quantum technologies.

In comparison to bright pulses, better stability that is not susceptible to loss makes dark pulses accessible for applications in such fields as signal processing, optics sensing, and quantum communication. Here we investigate the dual-wavelength domain-wall dark pulse generation in a graded-index multimode fiber (GIMF) based anomalous dispersion single-mode fiber (SMF) laser. By optimizing intra-cavity nonlinearity and pulse polarization, the mode-locked states can evolve each other between bright pulses, dark pulses, and bright-dark pulse pairs. The evolution mechanism among them may be relevant to the coherent mode superposition, spectral filtering, and mode selection in SMF-GIMF-SMF hybrid-fiber modulation devices that affect the pulse formation and evolution in temporal, frequency, and space domains. These results provide a valuable reference for promoting further development of nonlinear optics and ultrafast optics, in which ultrafast photonic devices, with low cost, simple manufacture as well as wide adaptability, as novel pulsed generation technique, play a vital role.

When pursuing femtosecond-scale ultrashort pulse optical communication, one cannot overlook higher-order nonlinear effects. Based on the fundamental theoretical model of the variable coefficient coupled high-order nonlinear Schrödinger equation, we analytically explore the evolution of optical solitons in the presence of high-order nonlinear effects. Moreover, the interactions between two nearby optical solitons and their transmission in a nonuniform fiber are investigated. The stability of optical soliton transmission and interactions are found to be destroyed to varying degrees due to higher-order nonlinear effects. The outcomes may offer some theoretical references for achieving ultra-high energy optical solitons in the future.

High-order quantum coherence reveals the statistical correlation of quantum particles. Manipulation of quantum coherence of light in the temporal domain enables the production of the single-photon source, which has become one of the most important quantum resources. High-order quantum coherence in the spatial domain plays a crucial role in a variety of applications, such as quantum imaging, holography, and microscopy. However, the active control of second-order spatial quantum coherence remains a challenging task. Here we predict theoretically and demonstrate experimentally the first active manipulation of second-order spatial quantum coherence, which exhibits the capability of switching between bunching and anti-bunching, by mapping the entanglement of spatially structured photons. We also show that signal processing based on quantum coherence exhibits robust resistance to intensity disturbance. Our findings not only enhance existing applications but also pave the way for broader utilization of higher-order spatial quantum coherence.

Detecting tiny deformations or vibrations, particularly those associated with strains below 1%, is essential in various technological applications. Traditional intrinsic materials, including metals and semiconductors, face challenges in simultaneously achieving initial metallic state and strain-induced insulating state, hindering the development of highly sensitive mechanical sensors. Here we report an ultrasensitive mechanical sensor based on a strain-induced tunable ordered array of metallic and insulating states in the single-crystal bronze-phase vanadium dioxide [VO$_{2}$(B)] quantum material. It is shown that the initial metallic state in the VO$_{2}$(B) flake can be tuned to the insulating state by applying a weak uniaxial tensile strain. Such a unique property gives rise to a record-high gauge factor of above 607970, surpassing previous values by an order of magnitude, with excellent linearity and mechanical resilience as well as durability. As a proof-of-concept application, we use our proposed mechanical sensor to demonstrate precise sensing of the micro piece, gentle airflows and water droplets. We attribute the superior performance of the sensor to the strain-induced continuous metal-insulator transition in the single-crystal VO$_{2}$(B) flake, evidenced by experimental and simulation results. Our findings highlight the potential of exploiting correlated quantum materials for next-generation ultrasensitive flexible mechanical sensors, addressing critical limitations in traditional materials.

Band convergence is considered to be a strategy with clear benefits for thermoelectric performance, generally favoring the co-optimization of conductivity and Seebeck coefficients, and the conventional means include elemental filling to regulate the band. However, the influence of the most electronegative fluorine on the CoSb$_{3}$ band remains unclear. We carry out density-functional-theory calculations and show that the valence band maximum gradually shifts downward with the increase of fluorine filling, lastly the valence band maximum converges to the highly degenerated secondary valence bands in fluorine-filled skutterudites. The effective degeneracy near the secondary valence band promotes more valleys to participate in electric transport, leading to a carrier mobility of more than the threefold and nearly twofold effective mass for F$_{0.1}$Co$_{4}$Sb$_{12}$ compared to Co$_{4}$Sb$_{12}$. This work provides a new and promising route to boost the thermoelectric properties of p-type skutterudites.

While density functional theory (DFT) serves as a prevalent computational approach in electronic structure calculations, its computational demands and scalability limitations persist. Recently, leveraging neural networks to parameterize the Kohn–Sham DFT Hamiltonian has emerged as a promising avenue for accelerating electronic structure computations. Despite advancements, challenges such as the necessity for computing extensive DFT training data to explore each new system and the complexity of establishing accurate machine learning models for multi-elemental materials still exist. Addressing these hurdles, this study introduces a universal electronic Hamiltonian model trained on Hamiltonian matrices obtained from first-principles DFT calculations of nearly all crystal structures on the Materials Project. We demonstrate its generality in predicting electronic structures across the whole periodic table, including complex multi-elemental systems, solid-state electrolytes, Moiré twisted bilayer heterostructure, and metal-organic frameworks. Moreover, we utilize the universal model to conduct high-throughput calculations of electronic structures for crystals in GNoME datasets, identifying 3940 crystals with direct band gaps and 5109 crystals with flat bands. By offering a reliable efficient framework for computing electronic properties, this universal Hamiltonian model lays the groundwork for advancements in diverse fields, such as easily providing a huge data set of electronic structures and also making the materials design across the whole periodic table possible.

The reliance on spin-orbit coupling or strong magnetic fields has always posed significant challenges for the mass production and even laboratory realization of most topological materials. Valley-based topological zero-line modes have attracted widespread attention due to their substantial advantage of being initially realizable with just an external electric field. However, the uncontrollable nature of electrode alignment and precise fabrication has greatly hindered the advancement in this field. By utilizing minimally twisted bilayer graphene and introducing exchange fields from magnetic substrates, we successfully realize a spin-resolved, electrode-free topological zero-line mode. Further integration of electrodes that do not require alignment considerations significantly enhances the tunability of the system's band structure. Our approach offers a promising new support for the dazzling potential of topological zero-line mode in the realm of low-energy-consumption electronics.

We present a study on inelastic thermoelectric devices, wherein charge currents and electronic and phononic heat currents are intricately interconnected. The employment of double quantum dots in conjunction with a phonon reservoir positions them as promising candidates for quantum thermoelectric diodes and transistors. We illustrate that quantum coherence yields significant charge and Seebeck rectification effects. It is worth noting that, while the thermal transistor effect is observable in the linear response regime, especially when phonon-assisted inelastic processes dominate the transport, quantum coherence does not enhance thermal amplification. Our work may provide valuable insights for the optimization of inelastic thermoelectric devices.

We systematically investigate in-plane transport properties of ternary chalcogenide Bi$_{2}$Rh$_{3}$Se$_{2}$. Upon rotating the magnetic field within the plane of the sample, one can distinctly detect the presence of both planar Hall resistance and anisotropic longitudinal resistance, and the phenomena appeared are precisely described by the theoretical formulation of the planar Hall effect (PHE). In addition, anisotropic orbital magnetoresistance rather than topologically nontrivial chiral anomalies dominates the PHE in Bi$_{2}$Rh$_{3}$Se$_{2}$. The finding not only provides another platform for understanding the mechanism of PHE, but could also be beneficial for future planar Hall sensors based on two-dimensional materials.

The rattling mode, an anharmonic vibrational phonon, is widely recognized as a critical factor in the emergence of superconductivity in caged materials. Here, we present a counterexample in a filled-skutterudite superconductor Ba$_{x}$Ir$_{4}$Sb$_{12}$ ($x = 0.8$, 0.9, 1.0), synthesized via a high-pressure route. Transport measurements down to liquid $^{3}$He temperatures reveal a transition temperature ($T_{\rm c}$) of 1.2 K and an upper critical field ($H_{\rm c2}$) of 1.3 T. Unlike other superconductors with caged structures, the Ba$_{x}$Ir$_{4}X_{12}$ ($X = {\rm P}$, As, Sb) family exhibits a monotonic decreasing $T_{\rm c}$ with the enhancement of the rattling mode, as indicated by fitting the Bloch–Grüneisen formula. Theoretical analysis suggests that electron doping from Ba transforms the direct bandgap IrSb$_{3}$ into a metal, with the Fermi surface dominated by the hybridization of Ir 5$d$ and Sb 5$p$ orbitals. Our findings of decoupled rattling modes and superconductivity distinguish the Ba$_{x}$Ir$_{4}$Sb$_{12}$ family from other caged superconductors, warranting further exploration into the underlying mechanism.

This review provides a comprehensive overview of current research on the structural, electronic, and magnetic characteristics of the recently discovered high-temperature superconductor La$_3$Ni$_2$O$_7$ under high pressures. We present the experimental results for synthesizing and characterizing this material, derived from measurements of transport, thermodynamics, and various spectroscopic techniques, and discuss their physical implications. We also explore theoretical models proposed to describe the electronic structures and superconducting pairing symmetry in La$_3$Ni$_2$O$_7$, highlighting the intricate interplay between electronic correlations and magnetic interactions. Despite these advances, challenges remain in growing high-quality samples free of extrinsic phases and oxygen deficiencies and in developing reliable measurement tools for determining diamagnetism and other physical quantities under high pressures. Further investigations in these areas are essential to deepening our understanding of the physical properties of La$_3$Ni$_2$O$_7$ and unlocking its superconducting pairing mechanism.

The 0.98(K$_{0.5}$Na$_{0.5})$NbO$_{3}$-0.02Ba(Nb$_{0.5}$Co$_{0.5})$O$_{3-\delta}$ ceramics with doped Ba$^{2+}$ and Co$^{2+}$ ions are fabricated, and the impacts of the thermal process are studied. Compared with the rapidly cooled (RC) sample, the slowly cooled (SC) sample possesses superior dielectric and ferroelectric properties, and an 11 K higher ferroelectric-paraelectric phase transition temperature, which can be attributed to the structural characteristics such as the grain size and the degree of anisotropy. Heat treatment can reversibly modulate the content of the oxygen vacancies, and in turn the ferroelectric hysteresis loops of the samples. Finally, robust and tunable ferroelectric property is achieved in SC samples with good structural integrity.

The pursuit of high-energy cathode materials has been focused on raising the charging cutoff voltage of nickel (Ni)-rich layered oxide cathode such as LiNi$_{0.8}$Co$_{0.1}$Mn$_{0.1}$O$_{2}$ (NCM811). However, the NCM811 suffers from rapid capacity fading upon cycling at cutoff voltage higher than 4.5 V, owing to their structural degradation and labile surface reactivity. Surface-coating with solid electrolytes has been recognized as an effective method to mitigate the performance failure of NCM811 at high voltage. Herein, the nano-sized Li$_{6.4}$La$_{3}$Ta$_{0.6}$Zr$_{1.4}$O$_{12}$ (LLZTO) is uniformly coated on the surface of single-crystal NCM811 particles, accompanied with the long-range Ta$^{5+}$ diffusion into the transition metal layer of NCM811 lattice. It is revealed that the LLZTO coating can not only inhibit the surface reactions of NCM811 with liquid electrolytes but also play an important role in suppressing the bulk microcracking within the NCM811 particles. The incorporation of Ta$^{5+}$ ion expands the lattice spacing and thereby improves the homogeneity of the Li$^{+}$ diffusion in the single-crystal NCM811, which alleviates the mechanical strain and intragranular cracks caused by nonuniform phases-transformation at high charging voltage. The synergy of surface protection and structural stabilization realized by LLZTO coating enables the NCM811-based lithium batteries to achieve a remarkable electrochemical performance. Typically, LLZTO coated NCM811 delivers a high reversible specific capacity of 202.1 mAh$\cdot$g$^{-1}$ with an excellent capacity retention as high as 70% over 1000 cycles upon charging to 4.5 V at 1 C.

Compared to commercial lithium-ion batteries, all-solid-state batteries can greatly increase the energy density, safety, and cycle life of batteries. The development of solid-state electrolyte with high lithium-ion conductivity and wide electrochemical window is the key for all-solid-state batteries. In this work, we report on the achievement of high ionic conductivity in the PAN/LiClO$_{4}$/BaTiO$_{3}$ composite solid electrolyte (CSE) prepared by solution casting method. Our experimental results show that the PAN-based composite polymer electrolyte with 5 wt% BaTiO$_{3}$ possesses a high room-temperature lithium-ion conductivity ($9.85\times 10^{-4}$ S$\cdot$cm$^{-1})$, high lithium-ion transfer number (0.63), wide electrochemical window (4.9 V vs Li$^{+}$/Li). The Li$|$Li symmetric battery assembled with 5 wt% BaTiO$_{3}$ can be stably circulated for 800 h at 0.1 mA$\cdot$cm$^{-2}$, and the LiFePO$_{4}|$CSE$|$Li battery maintains a capacity retention of 86.2% after 50 cycles at a rate of 0.3 C. The influence of BaTiO$_{3}$ ceramic powder on the properties of PAN-based polymer electrolytes is analyzed. Our results provide a new avenue for future research in the all-solid-state lithium battery technology.

Using micromagnetic simulations, we demonstrate the tilted perpendicular anisotropy-induced spin-orbit ratchet effect. In spin-orbit torque (SOT)-induced magnetization switching, the critical currents required to switch between the two magnetization states (upward and downward magnetization) are asymmetric. In addition, in the nanowire structure, tilted anisotropy induces formation of tilted domain walls (DWs). The tilted DWs exhibit a ratchet behavior during motion. The ratchet effect during switching and DW motions can be tuned by changing the current direction with respect to the tilting direction of anisotropy. The ratchet motion of the DWs can be used to mimic the leaky-integrate-fire function of a biological neuron, especially the asymmetric property of the “potential” and “reset” processes. Our results provide a full understanding of the influence of tilted perpendicular anisotropy on SOT-induced magnetization switching and DW motion, and are beneficial for designs of further SOT-based devices.