Regular Article

A note on the time evolution of a density operator interpolating between pure and mixed states

¹ Centro de Ciência e Tecnologia em Energia e Sustentabilidade, Universidade Federal do Recôncavo da Bahia, 44085-132, Feira de Santana, BA, Brazil
² Instituto de Física, Universidade Federal da Bahia, 40210-340, Salvador, BA, Brazil

^a e-mail: erico@ufrb.edu.br
^b e-mail: jmalboui@ufba.br

Received: 23 March 2020
Received in final form: 15 July 2020
Accepted: 1 September 2020
Published online: 12 October 2020

Abstract

In a recent paper [C.J.S. Ferreira, T.M. Silva, B. Baseia, Eur. Phys. J. B 92, 257 (2019)], the authors discuss the time evolution of statistical properties of a density operator that interpolates between pure and mixed states, assuming that the time evolution of the system is carried out by a specific time dependence of the coefficients that weight the admixing of the states. Here, we show that this assumption does not correspond exactly to any physical time evolution of the initial state of the system, being only a specific approximation. We present the exact evolution of the system in contact with a dissipative reservoir at zero temperature and discuss the time evolution of interpolations of pure and mixed states.