Annalen der Physik最新文献

The quest for high-temperature superconductivity has recently been revolutionized by high-pressure hydrides, such as H₃S and LaH₁₀, however, their practical potential is limited by the extreme stabilization pressures. Ternary hydrides have emerged as a promising avenue to mitigate this pressure constraint and further enhance their superconducting properties. The increased compositional complexity in ternary ones offers greater structural versatility and tunability, leading to successful syntheses of compounds like La–Ce–H system and Lu–Y–H system at significantly lower pressures. This review comprehensively surveys the experimental advances in ternary hydride superconductors, highlighting recent discoveries across different structural families. Nevertheless, research in this domain faces substantial challenges, including synthetic inhomogeneity, complex phase diagrams, and difficulties in precise structural determination of hydrogen sublattices. This review also outlines future research trajectories, high pressure, conventional superconductivity, electron-phonon coupling, superconductor, ternary hydridesaimed at achieving high-temperature superconductivity under more practical conditions.

A hidden variables (HVs) model is reported, which reproduces quantum predictions for Bell-Clauser-Horne-Shimony-Holt (Bell-CHSH) tests. The existence of such a model poses some limitations to quantum certifications that rely on Bell-CHSH inequality violations. The reported model does not prove wrong Bell's theorem. The latter assumes the factorability of the probability density p_AB, which rules the stochastic behavior of the HVs. The reported HVs model is based on an extended form of p_AB, which is suggested by Lebesgue's decomposition theorem for bounded functions. The considered p_AB complies with locality and realism, and also with measurement independence, parameter independence and outcome independence.

In this study, we investigate the emergence of non-trivial topological phases in a 1D spin-1/2 XX model induced by anisotropic four-spin interactions. By employing the fermionization technique, we precisely diagonalize the system's Hamiltonian and analytically identify three critical lines. Subsequently, we calculate the energy gap, fidelity susceptibility, cluster local order parameters, winding number, and entanglement spectrum. Our findings identify three crucial boundaries that divide five gapped phases, each characterized by the coexistence of symmetry-protected topological order and spontaneous symmetry breaking. Analyzing the winding number as a topological invariant allows us to distinguish these gapped phases as distinct non-trivial topological phases, characterized by integer values of $��\nu �=�\pm �3�,�\pm �1�$. Moreover, we observe topological phase transitions at quantum critical points, where the winding number changes are associated with the closing and reopening of the energy gap. Furthermore, we demonstrate that for a given winding number $�\nu$, the degeneracy of the lowest eigenvalue in the entanglement spectrum is generally $��2�\left|�\nu �\right|�$. This work provides novel insights into the role of anisotropic four-spin interactions in driving topological phenomena in low-dimensional quantum systems, offering a deeper understanding of the interplay between topology and quantum fluctuations.

The interplay between Floquet periodically driving and non-Hermiticity could bring about intriguing novel phenomena with anomalous Floquet topological phases of a finite-size, tight-binding lattice model. How to efficiently investigate on quasi-energy and eigenstate distribution of a non-Hermitian Floquet system with complicated driving protocol remains a challenging task. In this work, we define a somewhat complex driving protocol for a bipartite lattice system for the investigation. Thereafter, we introduce unsupervised learning method in order to explore distribution features of system eigenfunctions under different magnitude of system energy gain/loss. An amortized clustering strategy is adopted to perform state classification. We further introduce an algorithm-selection mechanism that adapts to varying gain/loss strengths by choosing the most suitable clustering model based on unsupervised indices and task-oriented separability. Proper employment of the selector enables us to reveal the categories of eigenstate distribution from abundant possible wave function distribution in two-dimension lattice in another efficient way. In addition, our work provides a feasible methodology via machine Amortized Clustering, Periodically Driven non-Hermitian Lattice, nomalous Hybrid Floquet Modeslearning method to assist in classification of Floquet modes.

The pursuit of high-temperature superconductors at ambient pressure represents one of the foremost challenges in contemporary condensed matter physics, particularly within the realm of hydride materials. This review presents recent theoretical breakthroughs and experimental advances in binary/ternary hydrides and boron–carbon/boron–nitrogen clathrates, highlighting their emergence as candidates for superconductivity. We establish an analytical framework examining the critical relationship between hydrogen content, crystal structure, and electron–phonon coupling, illuminating how some ternary systems circumvent the extreme pressure requirements of their binary counterparts through chemical diversity and lattice stabilization. We introduce a new superconducting quality factor that serves as a metric correlating critical temperatures with stability pressures, providing a unified basis for comparative evaluation across material systems. Hydride superconductors achieve elevated transition temperatures through strong electron–phonon coupling facilitated by hydrogen atoms incorporated within metallic lattices or metallic host frameworks, though many require high pressures for stabilization. Boron–carbon/boron–nitrogen compounds serve as hydride substitutes, with clathrates offering exceptional tunability through their cage-like frameworks, while both systems potentially provide high-temperature superconductivity under more accessible conditions. We systematically address persistent challenges in thermodynamic stability and critical temperatures, ultimately aiming to accelerate the discovery of practically viable superconducting hydrides and clathrates by establishing clear structure-property relationships and identifying pathways for future investigation.

Vortex beams carrying orbital angular momentum (OAM) have garnered significant research interest due to their broad applications in areas such as optical communications and particle manipulation. However, progress in this field has been hindered by a fundamental constraint: the intrinsic coupling between topological charge and beam radius in conventional vortex beams. Perfect vortex beams (PVBs) offer a solution to this limitation by decoupling the topological charge from the radial extent of the beam. Moreover, metasurfaces—benefiting from their inherent integrability and flexibility—can employ various phase modulation mechanisms to replace traditional, bulky optical systems based on spiral phase plates, axicons, and Fourier lenses. This review outlines the fundamental principles for generating PVBs and categorizes different metasurface-based approaches. It highlights a synergistic innovation strategy that integrates multidimensional light-field control with device-level miniaturization. Through precise design of subwavelength structures, metasurfaces not only contribute to the miniaturization and weight reduction of optical systems, but also exhibit exceptional capabilities in phase manipulation across a wide spectral range, from visible to terahertz frequencies.