Correlation Inequalities for the Quantum XY Model

Costanza Benassi; Benjamin Lees; Daniel Ueltschi

doi:10.1007/s10955-016-1580-2

Correlation Inequalities for the Quantum XY Model

J Stat Phys. 2016:164:1157-1166. doi: 10.1007/s10955-016-1580-2. Epub 2016 Jul 11.

Authors

Costanza Benassi¹, Benjamin Lees¹, Daniel Ueltschi¹

Affiliation

¹ Department of Mathematics, University of Warwick, Coventry, CV4 7AL UK.

Abstract

We show the positivity or negativity of truncated correlation functions in the quantum XY model with spin 1/2 (at any temperature) and spin 1 (in the ground state). These Griffiths-Ginibre inequalities of the second kind generalise an earlier result of Gallavotti.

Keywords: Correlation inequalities; Griffiths inequalities; Quantum XY model.