Comment on equivalence between quantum phase transition phenomena in radiation-matter and magnetic systems
Quantum Physics
2007-05-23 v1
Abstract
In this Comment we show that the temperature-dependent effective Hamiltonian derived by Reslen {\it et al} [Europhys. Lett., {\bf 69} (2005) 8] or that one by Liberti and Zaffino [arXiv:cond-mat/0503742] for the Dicke model cannot be correct for any temperature. They both violate a rigorous result. The former is correct only in the quantum (zero-temperature) limit while the last one only in the classical (infinite temperature) limit. The fact that the Dicke model belongs to the universality class of the infinitely coordinated transverse-field XY model is known for more then 30 years.
Keywords
Cite
@article{arxiv.quant-ph/0506207,
title = {Comment on equivalence between quantum phase transition phenomena in radiation-matter and magnetic systems},
author = {J. G. Brankov and N. S. Tonchev and V. A. Zagrebnov},
journal= {arXiv preprint arXiv:quant-ph/0506207},
year = {2007}
}
Comments
5 pages, no figures