arXiv:1812.00643 · Physical Review A
Cluster methods for the description of a driven-dissipative spin model
Dolf Huybrechts, Michiel Wouters
Abstract
We study the influence of short-range quantum correlations and classical spatial correlations on the phase diagram of the dissipative XYZ model by using a Gutzwiller Monte Carlo method and a cluster Gutzwiller ansatz for the wave function. Considering lattices of finite size we confirm the emergence of a region with ferromagnetic correlations and two paramagnetic regions and show the emergence of a region with a buildup of ferromagnetic correlations completely missed by mean-field theory. The inclusion of short-range quantum correlations causes drastic alterations of the mean-field correlation functions but our results show that the inclusion of long-range quantum correlations or the use of more sophisticated methods is needed to quantitatively match the exact results. A study of the susceptibility tensor shows that reciprocity is broken, a feature not observed in closed quantum systems. Furthermore, increasing the magnetic field suppresses the magnetization; this is also in contrast with closed quantum systems.