The European Physical Journal D最新文献

Motivated by the prospect of triangular spin cells for quantum information processing, we propose a model featuring spin–orbit interactions on the rungs and magnetic field effects along the legs. Quantum memory can enhance measurement precision for two incompatible observables in the physical system. In this work, we have examined the dynamics of entropic uncertainty and pairwise entanglement for a system of three-spin ( -1/2 ) particles interacting with a quantum memory in the presence of intrinsic decoherence and a non-uniform magnetic field. We employ logarithmic negativity to measure entanglement and study its evolution in a non-uniform magnetic field and decoherence. In addition, we examine and evaluate the operation of the entropic uncertainty relation for non-commuting observables in the three-spin system, analyzing its behavior under identical circumstances. According to the study, entropic uncertainty increases and entanglement decays due to intrinsic decoherence, whereas non-uniform magnetic fields produce complex entanglement patterns. Notably, entanglement and entropic uncertainty can display synchronized oscillatory behavior in specific situations, indicating possible approaches to alleviate decoherence in quantum memories. The fundamental characteristics and constraints of quantum memories are better understood thanks to this work, which also highlights how crucial it is to consider realistic environmental effects when creating quantum technologies.

We present experimental results of characterization of Silicon photomultipliers (SiPM) in a temperature range from 90 mK to 40 K and compare them to room-temperature results. Two SiPMs, one from ONSEMI and one from Hamamatsu Photonics, were tested. Operating voltage ranges, dark count rates, afterpulsing effects and photon detection efficiencies (PDE) were determined with illumination by 275- and 470-nm light fed into the cryostat via an optical fiber. A cryogenic shutter provided a true dark condition, where thermal radiation from room temperature is shielded and the thermal excitations in the chips are frozen. A second tunneling breakdown was observed at this condition, which substantially limits the operating voltage range for the temperatures 20–30 K. Below (sim )5 K, both SiPMs recover to an operating overvoltage range of 3–5 V. We found the chips function through the entire tested temperature range and are capable of withstanding thermal cycling with no major performance degradation.

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.