The European Physical Journal D最新文献

Superradiant phase transition and entanglement entropy in the Dicke model with a squeezed light are investigated. We find a special rotation coordinate system mapping the original Hamiltonian into an effective dual-oscillator Hamiltonian in the thermodynamic limit. We analytically derive the eigenenergy and eigenstate of the ground state. The ground state is demonstrated to undergo superradiant phase transition at a nonlinear critical boundary collectively induced by the squeezed driving and qubit-field coupling. This phase boundary requires neither large qubit-field detuning nor strong squeezed driving. An exact expression of the ground-state entropy is obtained. We demonstrate that the squeezed light enhances the qubit-field entanglement entropy linearly.

A theoretical inquiry delves into the presence of multiple solitons and breather configurations within a nonuniform, inhomogeneous, unmagnetized dusty plasma characterized by universally polarized force. This system encompasses ions, electrons, positively and negatively charged dust particles, distributed in accordance with a superthermal distribution. Employing the reductive perturbation technique (RPT), the Gardner equation (GE) is derived from the fundamental hydrodynamical model equations. The multi-solitons of the GE are synthesized utilizing the Hirota bilinear method (HBM), which further facilitates the exploration of breather solutions via the appropriate selection of complex wave numbers. The system exhibits both compressive and rarefactive multi-solitons. Moreover, the behavior of breather structures varies depending on associated plasma parameters; occasionally, they overlap, while at other times, they remain entirely disjoint. This research holds relevance for investigating the propagation of finite-amplitude waves in natural phenomena such as the atmosphere, oceans, optic fibers, and signal processing.

Figures display the interaction between two-solitons (a), and breather structures (b), of the Gardner equation in dusty plasma with polarized force for the parameter values (k_i = 5, k_e = 2.5, mu _i = 0.7, mu _e = 0.3, mu = 10, rho = 1.01, sigma _i = 0.1, R = 0.5, Z = 0.01), respectively. The manuscript presents some graphs to illustrate the propagation and interaction between two-soliton solutions, as well as the propagation of various breather structures in dusty plasma under polarized force. We explore the presented wave solutions using the symbolic computation software Mathematica. The diversity in two-solitons and breather structures depends on the plasma parameter and the choice of wave number, real or complex. This work analyzes, through graphical representation, how the plasma system affects the above nonlinear structures.

In this theoretical investigation, we have performed comprehensive quantum calculations to explore the pressure broadening effects on the (D_{1}left( 3,stext { }^{2}S_{1/2}-3ptext { }^{2}P_{1/2}right) ) and (D_{2}left( 3,s text { }^{2}S_{1/2}-3ptext { }^{2}P_{3/2}right) ) lines of the Mg( ^{+}) magnesium ion when surrounded by ground-state He helium atoms. Our objective is to delineate the profiles of these pressure-broadened resonance lines and scrutinize their behavior in response to binary collisions between Mg(^{+}) ions and He atoms. To accomplish this goal, we developed precise potential energy curves for the ground (X ^{2}Sigma _{1/2}^{+}) and the excited (A^{2}Pi _{1/2},A^{2}Pi _{3/2}) and B (^{2}Sigma _{1/2}^{+}), along with the associated transition dipole moments, using data derived from advanced ab initio methodologies such as SA-CASSCF, MRCI, and SO coupling, with Davidson and BSSE corrections. Our investigation encompasses a temperature range from 4000 to (12000 ,textrm{K}) and wavelengths spanning from 200 to (450,textrm{nm}). The theoretical profiles primarily exhibit dominant free-free transitions. Notably, around the (235,textrm{nm}) wavelength region, a satellite peak appears in the blue wing, attributed to the B (^{2}Sigma _{1/2}^{+}longleftarrow X ^{2}Sigma _{1/2}^{+}) transitions. We have confirmed agreement between our theoretical findings and prior research.

A Fabry–Perot interferometry was used to measure with a precision of about (10^{-4}) the Landé factor values of the levels issued from the 5s5p, 5s6d, 5s6s and 5s7p configurations of cadmium. Fully relativistic MCDHF calculations taking into account Breit and QED effects were performed to interpret the results of the experiment performed on the cadmium isotope 114. In addition to the four experimental Landé (g_J) values, new theoretical results for 12 levels are reported for the first time.

We report in this work the numerical study of the supercontinuum phenomenon raised from Airy pulses within a silicon-on-insulator waveguide including loss effects, third-harmonic generation (THG) and negative-frequency Kerr (NFK) terms. This study is conducted through a modeling based on the full unidirectional pulse propagation equation model which allows to assume the existence of the NFK term in the Kerr nonlinearity with a spectral filtering. The various effects of the linear loss, the free-carrier absorption/ free-carrier dispersion, the two-photon absorption, the THG, the NFK, the peak power, the pulse duration and the pulse shape are explored.

The Virtual Atomic and Molecular Data Centre (VAMDC) is a distributed infrastructure combining heterogeneous atomic and molecular (A &M) data from more than 41 autonomous databases. In this paper, we present the Species Database, a scientific web service which is a central catalogue providing a useful information on A &M species from all the VAMDC databases. The Species Database is one the key pillars in the technical architecture of the VAMDC, and from the user’s point of view, it is the service to simply and immediately answer the question: Does VAMDC have data on my molecule/atom of interest? This work is structured as follows: After recalling the aims and needs that led to the construction of the Species Database, we will describe how it works, with increasing levels of complexity. First, we will describe how any user, even those with no knowledge of VAMDC, can easily use the dedicated web interface to search for and extract information. Then we will describe an API that more advanced users can use to interact with the Species Database in a more programmatic way. Two appendices cover some technical aspects that are not necessary for using the Species Database, but which may be of interest to readers wishing to understand implementation details and low-level technical subtleties.

We describe the implementation of the current Flexible Atomic Code (FAC) unique electron central potential within the autostructure code. We show that the two codes then give the same atomic data for all practical application purposes. However, autostructure has more flexible potential options which can lead to a more accurate description of atomic processes, especially in low-charged ions.