Determination of the tunneling electron’s quantum state at the tunnel exit is a fundamental issue in the strong-field ionization. Recent experimental and theoretical investigations on atomic systems have established that the tunneling electron may populate highly excited states in the vicinity of the tunnel exit. Here, we address this tunneling-state problem for molecules by analyzing below-threshold harmonics (BTHs) emitted from the prototypical molecular system {\mathrm{H}}_2^{+} induced by the near-circularly polarized laser fields. The BTHs spectrum exhibits a double-plateau structure analogous to the atomic case. However, the cutoff energy of the first plateau displays a pronounced dependence not only on laser intensity but also on the internuclear distance R. These phenomena can be quantitatively described by a semiclassical strong-field model incorporating an analytical treatment of the near-nucleus Coulomb interaction, and attributing the first cutoff energy to the average energy of the excited bound state during tunneling. We further demonstrate that the R-dependent molecular Coulomb potential near the nucleus differs markedly from its atomic counterpart, yielding a significantly lower average energy for the molecular excited state. Our work provides critical evidence of tunneling-electron excitation before ionization in molecules, and sheds a light on the comprehensive understanding of tunneling phenomenon in strong field physics.

Ultrafast electron microscopy (UEM), also referred to as four-dimensional electron microscopy (4D-EM), has emerged as a transformative tool capable of recording atomic-scale dynamics with high spatiotemporal resolution. While the stroboscopic pump–probe mode has been extensively applied to reversible processes, many important phenomena are intrinsically irreversible and demand single-shot imaging. This review focuses on the principles and recent progress of single-shot 4D-EM for capturing non-repeatable events in space and time. We describe the two main single-shot modalities — single-frame and movie-mode (multi-frame) imaging — which rely on intense, ultrashort electron pulses to capture a transient following a single pump excitation. Representative applications are systematically surveyed, including laser-induced melting and rapid solidification, phase transitions, nanoparticle jumping and coalescence, redox and eutectic reaction dynamics, and liquid-phase behaviors. Key challenges, including the conflict between electron number and pulse duration imposed by space-charge effects, beam coherence, and detector limitations, are discussed, where correspondingly future perspectives and strategies are offered. The progress establishes single-shot 4D-EM as an indispensable platform for unraveling irreversible and stochastic processes across materials science, chemistry, physics, and biology.

Mid-infrared (mid-IR) ultrafast laser sources, which cover the molecular vibrational fingerprint region and atmospheric transmission window, have garnered widespread attention due to their significant applications in spectroscopy, biomedicine, environmental monitoring, and precision machining. In recent years, rapid advances in ultrafast fiber lasers, nonlinear frequency conversion, and novel fiber technologies have greatly advanced mid-infrared ultrafast laser sources. Currently, the primary methods for generating mid-IR ultrafast sources include direct mode-locked lasers based on gain media and indirect schemes relying on nonlinear frequency conversion. Direct sources offer compactness and operational stability but are limited by gain bandwidth and material constraints, while indirect approaches provide broader wavelength tunability and spectral coverage through nonlinear optical processes, albeit with increased system complexity. This review focuses on the major advances in mid-infrared ultrafast sources over the past decade and systematically reviews their generation mechanisms and key technologies, with particular emphasis on nonlinear frequency conversion based on difference frequency generation. This approach employs a broadband femtosecond fiber laser as the pump source, enabling broadband, highly coherent mid-IR radiation output, and offer advantages such as a compact structure, high stability, and low cost. Furthermore, this review summarizes typical applications of mid-IR ultrafast sources in environmental monitoring, medical diagnostics, and precision machining, and discusses the potential of artificial intelligence optimization methods and novel fiber platforms, including hollow-core anti-resonant fibers, in pulse modulation, enhancement of nonlinear frequency conversion efficiency, and long-wavelength transmission. With the continuous development of high-energy ultrashort pulse fiber lasers, novel nonlinear materials, and advanced fiber structures, mid-infrared ultrafast laser sources are expected to achieve broader spectral coverage, higher pulse energy, and longer output wavelengths, thereby providing stronger support for future scientific research and engineering applications.

Variational quantum algorithms (VQAs) have established themselves as a central computational paradigm in the Noisy Intermediate-Scale Quantum (NISQ) era. By coupling parameterized quantum circuits with classical optimization, they operate effectively under strict hardware limitations. However, as quantum architectures transition toward early fault-tolerant (EFT) and ultimate fault-tolerant (FT) regimes, the foundational principles and long-term viability of VQAs require systematic reassessment. This review offers a comprehensive analysis of VQAs and their progression toward the FT regime. We deconstruct the core algorithmic framework by examining ansatz design and classical optimization strategies, including cost function formulation, gradient computation, and optimizer selection. Concurrently, we evaluate critical training bottlenecks, notably barren plateaus (BPs), alongside established mitigation strategies. The discussion then explores the EFT phase, detailing how the integration of quantum error mitigation (QEM) and partial error correction can sustain algorithmic performance. Addressing the FT phase, we analyze the inherent challenges confronting current hybrid VQA models. Furthermore, we synthesize recent VQA applications across diverse domains, including many-body physics, quantum chemistry, machine learning, and mathematical optimization. Ultimately, this review outlines a theoretical roadmap for adapting quantum algorithms to future hardware generations, elucidating how variational principles can be systematically refined to maintain their relevance and efficiency within an error-corrected computational environment.

The nonlinear magnon−phonon coupling enables magnetic materials promising platforms for fabricating phonon combs that are powerful tools for sensing, imaging, and quantum information applications. However, magnetocrystalline anisotropy, crucial for stabilizing two-dimensional (2D) magnetic materials, has been largely overlooked in magnon−phonon coupling studies. In this work, we incorporate magnetocrystalline anisotropy to evaluate the strength of magnon−phonon coupling in monolayer CrI₃. We find that the {\mathrm{A}}_{1\mathrm{u}} mode at \sim 157.75{\mathrm{c}\mathrm{m}}^{-1} exhibits the strongest magnon−phonon coupling (\sim 2.6{\mathrm{c}\mathrm{m}}^{-1}) arising from the large parallel movements along the out-of-plane direction (z-axis) of two magnetic {\mathrm{C}\mathrm{r}}^{3+} ions. This mode corresponds to a large frequency shift of \sim 86.23{\mathrm{c}\mathrm{m}}^{-1} between the nonmagnetic and ferromagnetic phases. More interestingly, magnetocrystalline anisotropy exhibits mode-dependent effects on magnon−phonon coupling. Specifically, it enhances the coupling strength of the A_1u mode by 22.02%, while suppressing that of {\text{A}}_{\text{1g}}^2, {\text{A}}_{\text{2g}}^2 and {\text{E}}_{\text{g}}^2 modes by 69.68%, 55.9%, and 19.17%, respectively. These results identify magnetocrystalline anisotropy as a previously unexplored, symmetry-selective control knob for magnon−phonon coupling in 2D magnets.

Non-Hermitian physics provides a powerful route for controlling wave propagation in open systems, yet its role in spatially inhomogeneous topological structures remains insufficiently clarified. Here, we experimentally demonstrate a spatially inhomogeneous non-Hermitian topological metasurface on a microwave microstrip platform. A continuous geometric modulation introduces a position-dependent Dirac mass and forms a mass-domain-wall interface, while lumped resistive loading provides a controllable imaginary potential. This design transforms the conventional Hermitian degeneracy into a real-part degenerate region near the Γ point, accompanied by an imaginary-frequency bifurcation and mode-dependent attenuation. Tight-binding calculations, full-wave simulations, and microwave near-field measurements are used to characterize the complex bulk dispersion and lossy edge-state transport. We further show that the edge modes exhibit pseudospin-momentum-locked directional excitation, with non-Hermiticity providing an additional degree of freedom for attenuation and mode selectivity. These results clarify the distinct roles of geometric mass gradients and engineered dissipation, establishing a tunable microwave platform for loss-engineered topological wave transport.

Hexagonal MnTe is a prototypical semiconducting altermagnet whose properties are heavily influenced by intrinsic disorder, yet how the resulting diverse transport regimes shape its magnetotransport behavior remains to be clarified alongside the role of relativistic spin−orbit coupling (SOC). Here, we present a systematic study of the anisotropic magnetoresistance (AMR), planar Hall effect (PHE), and nonlinear transport in MnTe bulk single crystals. Below the Néel temperature (T_N ~ 304 K), the emergence of high-order harmonics in AMR and PHE within the high-temperature metallic regime reveals the interplay of magnetic order, crystalline symmetry, and SOC. At relatively lower temperatures, the disappearance of higher-order symmetries coincides with a transport crossover into the hopping conduction regime, suggesting that carrier localization diminishes the transport sensitivity to the Fermi-surface topology. In addition, we detect distinct second-order nonlinear Hall signals, providing evidence for a macroscopic inversion-asymmetric response in altermagnetic MnTe. Extending the investigations into the localized regime provides key insights into the subtle role of disorder and SOC in macroscopic charge transport. Our work thus underscores the necessity of exploring magnetotransport across diverse conducting regimes to comprehensively understand altermagnetic properties.

Superionic conductors (SICs) are attracting significant research attention for their potential applications in all-solid-state batteries. A key challenge in developing such SICs is the rational design of sulfide structural frameworks that enable rapid ion transport. Compared with the conventional trial-and-error approach, theory-driven computational methods offer powerful tools for accelerating materials discovery. In this study, we use the largest cavity diameter (LCD) as a descriptor and conduct high-throughput screening of sulfur-based silver compounds using the Materials Project (MP) database to identify promising superionic-state materials. Machine-learning force-field (MLFF)-accelerated molecular-dynamics (MD) simulations are performed on the selected structures, yielding seven candidate materials, including several previously reported systems. Furthermore, the superionic-state transition temperatures of these compounds are 300 K or higher. Notably, the LCD value is shown to be inversely proportional to the superionic-state transition temperature. This work establishes a quantitative structure–property relationship governing superionic-state transitions and provides a framework for future computational investigations of superionic materials.

High mobility is crucial for optoelectronic response and thermoelectric performance, while low thermal conductivity enhances the thermoelectric figure of merit (ZT) and reduces heat loss. PtTe₂, a novel two-dimension (2D) Dirac semimetal, is a promising optoelectronic and thermoelectric material. Here, we characterize 2D PtTe₂ films using transient thermal grating (TTG) and terahertz time-domain spectroscopy (THz-TDS). TTG reveals an extremely low thermal diffusion coefficient (~6.4 × 10⁻⁶ m²/s), much lower than most semiconductors and metals, likely from strong phonon−phonon scattering or phonon boundary scattering, with a corresponding thermal conductivity of ~10.4 W·m⁻¹·K⁻¹. THz-TDS shows excellent electrical transport: room-temperature conductivity reaches 4.7 × 10⁵ S/m and carrier mobility is 1870 cm²·V⁻¹·s⁻¹, attributed to its highly ordered crystal and Dirac band structure. The ZT is 0.002 at room temperature, comparable to reported values for 2D thermoelectric materials. Combining low thermal conductivity and high mobility, 2D PtTe₂ offers new opportunities for high-performance electronics and possible application in thermoelectrics.

We use a relativistic quark–diquark framework, with parameters fixed from meson and proton data, to calculate the magnetic moments of ground-state singly heavy baryons with spin J=\frac{1}{2} and J=\frac{3}{2} in both the charm and bottom sectors. The underlying two-body wave equation is solved self-consistently. The results reveal a systematic dynamical hierarchy: the heavy–light diquark configuration is more spatially extended than the light–light configuration, by a factor of 3–4 in charm baryons and by roughly an order of magnitude in bottom baryons. Because the heavy–light configuration carries the dominant weight in the magnetic-moment average, the predictions are largely controlled by this extended configuration, in which the light-quark dynamical mass remains close to its conventional constituent value; the tightly bound light–light configuration supplies only a small correction.