Eur. Phys. J. Plus (2022) 137: 155
https://doi.org/10.1140/epjp/s13360-022-02382-7

Regular Article

Entropy exchange and thermal fluctuations in the Jaynes–Cummings model

¹ Facultad de Ciencias - CUICBAS, Universidad de Colima, Bernal Díaz del Castillo No. 340, Col. Villas San Sebastián, 28045, Colima, Mexico
² Escuela de Ciencias Básicas Tecnología e Ingeniería ECBTI, Universidad Nacional Abierta y a Distancia UNAD, Bogotá, Colombia

Received: 18 November 2021
Accepted: 12 January 2022
Published online: 23 January 2022

Abstract

The time dependence of the quantum entropy for a two-level atom interacting with a single-cavity mode is computed using the Jaynes–Cummings model, when the initial state of the radiation field is prepared in a thermal state with temperature fluctuations. In order to describe the out-of-equilibrium situation, the Super-Statistics approximation is implemented so that the gamma and the multi-level distribution functions are used to introduce the inverse temperature fluctuations. In the case of the gamma distribution, paralleling the Tsallis non-additive formalism, the entropy for the system is computed with the q-logarithm prescription, and the impact of the initial state of the atom is also taken into account. The results show that, in the first distribution, the q-parameter (related to the thermal fluctuations) modifies the partial entropies appreciably. In contrast, the way the inverse temperatures are distributed in the second one may lead to changes in the entropy functions.