The European Physical Journal D最新文献

We point out two flaws in a paper published recently in this journal. The first one is that the parameters (r_e) and (D_e) in the screened Kratzer potential are not the equilibrium bond length and dissociation energy as the authors claimed. We show how to derive the correct expression for this potential. The second flaw is that the authors omitted the sum over the magnetic quantum number in the calculation of the canonical partition function. For this reason the resulting thermodynamic functions are of no practical utility.

We investigate a tripartite quantum system composed of a plasmon cavity, respectively, coupled to a single polarized molecule and an optical cavity. The aim is to explore the criticality-enhanced single-molecule frequency estimation by means of optical modification (OM) and squeezing parametric amplification (SPA) in together. In this context, we initially summarize the critical behaviors and patterns. Specifically, we identify a squeezing-degree-dependent critical point (CP) of one supermode. The eigen energy near the critical point shows a remarkable sensitivity to the weak mechanical frequency fluctuations. Consequently, we anticipate a significant augmentation in the precision of single-molecule frequency estimation utilizing this hybrid system. Within the framework of quantum metrology, a comprehensive evaluation of the measurement precision in the critical regime reveals the capacity of this proposal is significantly enhanced via a joint cooperation of OM and SPA.

1. A hybrid optomechanics-like system, a fresh system for quantum sensing. 2. Jointly assisted by the optical modification (OM) and squeezing parametric amplification (SPA), the system’s energy is engineered into a sensitive parameter to a weak variation around which critical points. We can realize a synergistic enhancement of single-molecule sensing in this attempt, namely OM+SPA

Scrambling of quantum information in both integrable and nonintegrable Floquet spin systems is studied. Our study employs tripartite mutual information (TMI), with negative TMI serving as an indicator of scrambling, where a more negative value suggests a higher degree of scrambling. Both integrable and nonintegrable Floquet systems display scrambling behavior across all periods lying between 0 and (pi /2), except at self-dual point ((pi /4)). Nonintegrable Floquet systems exhibit more pronounced scrambling compared to integrable ones across all periods. The degree of scrambling increases as we move toward the self-dual point (but not at the self-dual point), regardless of the initial states. TMI demonstrates periodic behavior at the self-dual point, with a period matching the system size in the case of the integrable system while displaying complex patterns in the nonintegrable system. The initial growth of scrambling in both integrable and nonintegrable Floquet systems manifests as a power-law increase for small periods, followed by a sudden jump in scrambling near the self-dual point.

Radiative K-shell transitions of weakly ionized copper, a key element among the iron-peak group, provide valuable diagnostics for both astrophysical objects and laboratory photoionized plasmas. In this work, we present atomic data for the K-shell radiative decay rates, photoionization cross sections, and autoionization rates, all of which are essential for accurate spectral modeling of such plasma. To access the reliability of these data, extensive comparisons with previously published results have been made, revealing uncertainties of only a few electron volts in the K-vacancy transition energies. With the upcoming generation of X-ray missions, which are expected to significantly increase effective area around 8 keV, the detection of copper K lines becomes promising and the spectral resolution of these missions is well matched to the accuracy of our calculations. The atomic data thus provide a consistent theoretical framework for interpreting the observed spectra and enhance our understanding of copper nucleosynthesis.

Quantum computing has emerged as a powerful tool for modeling molecular systems with high accuracy, accelerating the search for novel therapeutic targets. In this study, we present a two-stage hybrid workflow that combines a Quantum Graph Neural Network with a Variational Quantum Eigensolver to identify potent serine neutralizers in the QM9 dataset. In the first stage, an advanced quantum graph neural network architecture incorporating attention layers, self-distillation, and an adaptive learning-rate schedule is trained to predict ionization potentials and binding free energies. Across five independent random-seed trials, our adaptive-thresholded QGNN–VQE pipeline achieves an average (R^2) of (0.990 pm 0.008) and a mean absolute error of (0.034 pm 0.001) eV ((approx 0.79 pm 0.03) kcal/mol) on the QM9 validation set, demonstrating robust, chemical-accuracy-level predictions. Building on these high-precision predictions, the second stage employs a QAOA-inspired hybrid ranking scheme that merges quantum graph neural network outputs, feature-space similarity (via PCA and cosine similarity), and variational quantum eigensolver-derived energy stability. This (alpha )-weighted ((alpha = 0.95)) scoring framework is applied to over 133,000 molecules, efficiently parsed in parallel. The final ranked list is validated through an improved bijection test, featuring an adaptive similarity threshold to ensure both structural and functional robustness. The top-scoring candidate identified by our pipeline is 5,6,7-tetrahydro-4 H-pyrazolo[4,3-c]pyridin-4-one, highlighting the efficacy of quantum-enhanced modeling in pinpointing complex pharmacological targets. These findings underscore the transformative potential of hybrid quantum-classical workflows in drug discovery, offering a flexible blueprint for advanced screening of other critical biomolecular interactions in the rapidly expanding field of quantum biology.

VQE for Serine Neutralization

Electron-impact ionization cross sections are essential for plasma modeling. However, most previous studies have largely overlooked electron-impact multiple ionization (EIMI) processes. The EIMI process is expected to be important especially in high-temperature, non-equilibrium, or non-Maxwellian plasmas. Due to the current impracticality of quantum-mechanical calculations for EIMI cross sections, we here describe the integration of four semi-empirical models into JAC, the Jena Atomic Calculator. We demonstrate the applicability of these distinct models in accurately estimating EIMI cross sections. This module is intended to provide a fast and reliable tool for application to various, especially to understand the role of EIMI processes in astrophysics and the investigation of laser–particle interaction processes.

Electron-impact excitation from the ground state to the (2p_{3/2}) level of H-like ({EMPTY}^{197})Au({EMPTY}^{78+}) ions with nuclear spin (I=3/2) and the subsequent Lyman-(alpha _{1}) radiative decay are studied using the multiconfigurational Dirac–Hartree–Fock method and the relativistic distorted-wave theory. Special attention is paid to the hyperfine-induced effects on angular anisotropy of the Lyman-(alpha _{1}) line. To this aim, the partial cross sections for excitations to the magnetic substates of the (2p_{3/2}) level are calculated, from which the alignment parameters of the (2p_{3/2}) level and the corresponding hyperfine levels as well as the effective anisotropy parameter and the angular distribution of the Lyman-(alpha _{1}) line are obtained. It is found that the hyperfine interaction significantly weakens the anisotropy of the Lyman-(alpha _{1}) line, especially at low impact electron energies near the excitation threshold, when compared to the case of (I=0), the specific behavior of which exhibits a strong sensitivity to the impact energy. The present finding reveals the importance of including the hyperfine interaction in the relevant theoretical models and also provides a new perspective for explaining deviations between theoretical calculation and experimental measurement. Moreover, accurate angular anisotropy measurements of the Lyman-(alpha _{1}) line are suggested as a tool to explore the hyperfine interaction in highly charged few-electron ions.