Entanglement of Rydberg atoms successively passing a thermal cavity

We investigated the entanglement between two identical two-level Rydberg atoms successively passing cavity and interacting with one-mode field through a one-photon and degenerate two-photon processes. For two-photon interaction, we focused our attention on the study of atomic entanglement dynamics in the presence of the Stark shift and initial atomic coherence. For one-photon case we discussed the influence of atomic coherence, detuning and cavity thermal photons on the entanglement dynamics for entangled initial atomic states

Modeling of entanglement behavior of two dipole-coupled superconducting qubits interacting with quantum fields in lossless cavities

We have investigated the entanglement dynamics between two initially entangled superconducting qubits interacting with vacuum fields of one or two independent coplanar 1D resonators. Three types of two-qubits generalized Jaynes-Cummings models with different atom-field coupling constants and detunings and direct dipole-dipole interaction has been considered. Using the dressed-states technique we have derived the exact solutions for models under consideration. The computer modeling of the time dependence of qubit-qubit entanglement (negativity) has been carried out for different strength of the dipole-dipole interaction. Results show that dipole-dipole interaction may be used for entanglement control

Thermodynamic Derivation of the Tsallis and R\'enyi Entropy Formulas and the Temperature of Quark-Gluon Plasma

We derive Tsallis entropy, Sq, from universal thermostat independence and obtain the functional form of the corresponding generalized entropy-probability relation. Our result for finite thermostats interprets thermodynamically the subsystem temperature, T1, and the index q in terms of the temperature, T, entropy, S, and heat capacity, C of the reservoir as T1 = T exp(-S/C) and q = 1 - 1/C. In the infinite C limit, irrespective to the value of S, the Boltzmann-Gibbs approach is fully recovered. We apply this framework for the experimental determination of the original temperature of a finite thermostat, T, from the analysis of hadron spectra produced in high energy collisions, by analyzing frequently considered simple models of the quark-gluon plasma.Comment: 4 pages 1 Figure PRL style, revised presentatio

Entanglement between two Rydber atoms successively interacting with a detuned cavity field

Рассмотрена динамика двух ридберговских атомов, последовательно пролетающих вакуумный или тепловой резонатор одноатомного мазера, при наличии расстройки. В качестве начального состояния атомов выбирались различные перепутанные двухатомные состояния. С помощью параметра перепутывания (отрицательности) исследована динамика перепутывания атомов для вакуумного, так и для теплового поля. Проанализированы особенности поведения отрицательности для малых и больших значений параметра расстройки. Показано, что для теплового поля и малых расстроек в системе имеет место эффект мгновенной смерти перепутывания. Установлено также, что эффект исчезает для больших значений параметра расстройки. Показано, что наличие расстройки приводит к уменьшению осцилляций амплитуды перепутывания и его стабилизации как для вакуумного, так и для теплового поля. На основе полученных результатов сделан вывод, что расстройка может использоваться для контроля и управления степенью перепутывания атомов в одноатомном мазере. We have investigated two Rydberg atoms successively passing a vacuum or a thermal cavity of one-atom maser taking into account the detuning. The atoms was assumed to be initially prepared in the different separable of entangled states. Calculating the negativity we have investigated the dynamics of atom-atom entanglement both for the vacuum and the thermal field. The special features of negativity behavior have been studied comprehensively for small and large values of detunings. For thermal cavity field and small detunings we have established the effect of sudden death and birth of Entanglement. For large detunings, this negative effect can be eliminated. We derived that the presence of detuning leads to decreasing of the entanglement amplitude oscillations and stabilization of the degree of entanglement both for the vacuum and the thermal field. These results show that the atom-atom entanglement in one-atom maser can be controlled by the detuning

Influence of Stark Shift on Entanglement of Two Qubits in the Two-Photon Tavis-Cummings Model

Considering two-atom degenerate two-photon Tavis-Cummings model, we investigate the entanglement between two atoms prepared initially in the coherent disentangled states and cavity field prepared in few-photon Fock state, and study the effect of the Stark shift on entanglement. The results show that the atom–atom negativity evolve periodically with time and the periods are affected by the Stark shift and initial coherent atomic state and that the atom–atom entanglement can be greatly enhanced due to the presence of Stark shift. We also have shown that entanglement sudden death effect vanishes for some parameters of the considered system due to the presence of Stark shift. In addition, the entanglement sudden death effect vanishes due to the presence of Stark shift. We have derived that the dynamic Stark shift can be used to control entanglement between two initially disentangled atoms