Annalen der Physik最新文献

Resonance-enhanced multiphoton ionization (REMPI) in potassium atom is investigated within the strong coupling regime using photoelectron momentum imaging techniques. The kinetic energy distribution of the ionized electrons reveals the eigenenergies of the dressed states, which exhibit Autler–Townes (AT) splitting. This splitting is proportional to the laser field strength. Partial wave analysis of the photoelectrons angular distributions (PAD) uncovers relative phase shifts between the dressed states, shedding light on attosecond ionization time delays. The observed phase shift between the two electron wave packets by the AT splitting arises from the combined effects of the Coulomb phase and the quantum defect phase.

Hydrogen-based materials are able to possess extremely high superconducting critical temperatures, $��T_c�s�$, due to hydrogen's low atomic mass and strong electron–phonon interaction. Recently, a descriptor based on the Electron Localization Function (ELF) has enabled the rapid estimation of the $�T_c$ of hydrogen-containing compounds from electronic networking properties, but its applicability has been limited by the small size and homogeneity of the training dataset used. Herein, the model is re-examined, compiling a publicly available combined dataset of 244 binary and ternary hydride superconductors. The analysis shows that though ELF-based networking remains a valuable descriptor, its predictive power declines with increasing compositional complexity. However, by introducing the molecularity index, defined as the highest value of the ELF at which two hydrogen atoms connect, and applying symbolic regression, the accuracy of the predictions can be substantially enhanced. These results establish a more robust framework for assessing superconductivity in hydride materials, facilitating accelerated screening of novel candidates through integration with crystal structure prediction methods or high-throughput searches.

This study explores the temporal evolution of local quantum Fisher information and coherence in a graphene monolayer subjected to a polarized electromagnetic field, revealing significant effects driven by system parameters. In the absence of the field, the analysis highlights the crucial role of the initial state's purity in the dynamics of both local quantum Fisher information and coherence, influencing their amplitude and decay over time. Introducing an electromagnetic field unveils a strong dependence of these quantities on the polarization and amplitude parameters. For linear polarization, local quantum Fisher information and coherence reach their maximum values at specific field phases, while for circular polarization, the system's response becomes more complex, exhibiting pronounced variations and a gradual decrease in coherence at higher field intensities. These findings emphasize the importance of controlling electromagnetic parameters to manipulate quantum information in graphene and open up new prospects for applications in quantum electronics and information processing.

Superconducting quantum interference device (SQUID) gradiometers are sensitive instruments for detecting magnetic fields and are widely used in magnetocardiography (MCG). However, their performance is compromised by vibrations from foundations or refrigeration equipment. Vibration-induced effects on SQUID gradiometers occur through two main mechanisms. First, an initial angular deviation between the pickup coils prevents cancellation of the reversed magnetic flux from external fields. Vibration converts this inherent interference into a time-varying flux disturbance at the vibration frequency. Second, bubbles from boiling liquid helium passing through the gradiometer loops increase the gradiometer's noise floor in the frequency domain. Vibration alters the dynamic behavior of these bubbles. Finite element simulations are conducted to examine the influence of these mechanisms across various vibration frequencies, and the SQUID gradiometer's noise power spectral density is measured at six vibration frequencies. The noise contains both narrowband and broadband components: The narrowband noise primarily occurs at the vibration frequencies and their second harmonics when the pickup coil's angular displacement aligns with or is perpendicular to the vibration direction. Meanwhile, the introduction of vibrations elevates the broadband noise level relative to the non-vibration state. Moreover, the broadband noise exhibits distinct peaks at the gradiometer's intrinsic resonance frequency of 15 Hz.

There is no simple and universal analytical description of various micro-optical systems related with Fano resonances. This especially concerns modulated thin films, which, when coupled to external fields, show Fano resonances. Usually, such micro-optic schemes are simulated numerically, frequently by the use of commercial software. The study fills this gap of the lack of universal analytical description by introducing and exploring a simple mechanical equivalent, the oscillator chain, which mimics such schemes involving Fano resonances. The model does not necessarily provide the rigorous description of complicated micro-optical schemes, however does capture the main properties of such Fano-related micro-optical systems. The model captures different modifications of the thin film arrangement as well: thin film with amplification, non-Hermitical thin films, and others. It also covers the case of multiple Fano resonances in a thin film. The model is validated by comparing with the rigorously calculated wave propagation in the thin films.

Beam-splitters are basic and instrumental tools not only in the study of foundational issues in quantum mechanics, but also in various applications of quantum information processing. In the continuous-variable scenario involving quantum optical states and Gaussian quantum information, interference phenomena are widely investigated and characterized via beam-splitters. In this work, within the framework of stabilizer quantum computation in finite quantum systems, entanglement and magic correlations generated by discrete beam-splitters are explored. Two types of magic correlations are distinguished: mutual magic (analogous to quantum mutual information) and non-local magic. Explicit formulas for these correlations are derived in the qubit scenario where the beam-splitter is implemented by the controlled-NOT gate, with the $�H$-type magic states playing a particularly prominent role as input states. Extending to prime-dimensional qudit systems, it is shown that fiducial states of mutually unbiased bases also play a remarkable role. Basic properties of these magic correlations are revealed and illustrated through some typical examples.

This research investigates the dynamics of entanglement and uncertainty-induced nonlocality (UIN) in a spin-1/2 Ising-Heisenberg diamond chain subjected to local non-Markovian decoherence channels. By examining amplitude damping (AD) and random telegraph noise (RTN) in both zero and finite temperature regimes, the study reveals nuanced distinctions in the degradation and revival of quantum correlations. The interplay between intrinsic spin couplings, thermal effects, and memory-induced coherence backflow highlights the complex behavior of quantum resources under realistic noise conditions. Concurrence emerges as a sensitive marker of entanglement recovery in dephasing environments, while uncertainty-induced nonlocality proves more resilient in high-temperature or dissipative regimes. The analysis further demonstrates that moderate thermal activation and external magnetic fields can nontrivially enhance or suppress quantum features depending on system parameters. These findings offer a detailed perspective on the robustness and complementarity of different quantum correlation measures, providing guiding principles for the design of thermally stable and noise-resilient quantum information protocols.

Condensation stagnation, that is, the existence of a delay between nucleation and growth during gas-phase particle formation, is a crucial phenomenon that affects associated processes and manifests itself as the presence of supercritical clusters in resulting particulates. In previous work, this unique phenomenon was experimentally demonstrated in a magnesium (Mg) particle flame, and an empirical explanation for the mechanisms responsible for the phenomenon was provided. The occurrence of stagnant clusters was revealed using specially designed sampling. The analysis of collected products, however, could not provide details about their evolution, so no information on the cluster's lifespan (i.e., stagnation time) was available. In the current manuscript, the results of spectroscopic studies of the Mg particle flame in air are reported. The recently developed advanced processing analysis of pyrometry data makes it possible to identify the light emission signature of stagnant clusters and, accordingly, estimate their lifespan, that is, the time during which clusters have physical properties (e.g., emissivity) different from those of mature nano-oxides. The obtained time on the order of 10 ms seems to be sufficiently long, which allows one to consider stagnant clusters as a separate state of matter, and not as a metastable metal oxide material.