The von Neumann Entropy for Mixed States
Quantum Physics
2019-01-30 v1
Abstract
The Araki-Lieb inequality is commonly used to calculate the entropy of subsystems when they are initially in pure states as this forces the entropy of the two subsystems to be equal after the complete system evolves. Then, it is easy to calculate the entropy of a large subsystem by finding the entropy of the small one. To the best of our knowledge, there does not exist a way of calculating the entropy when one of the subsystems is initially in a mixed state. We show here that it is possible to use the Araki-Lieb inequality in this case and find the von Neumann entropy for the large (infinite) system. We show this in the two-level atom-field interaction.
Keywords
Cite
@article{arxiv.1804.09698,
title = {The von Neumann Entropy for Mixed States},
author = {Jorge A. Anaya-Contreras and Héctor M. Moya-Cessa and Arturo Zúñiga-Segundo},
journal= {arXiv preprint arXiv:1804.09698},
year = {2019}
}
Comments
10 pages, 4 figures