PHYSICAL REVIEW B 101, 214302 (2020) Validity of mean-field theory in a dissipative critical system: Liouvillian gap, PT-symmetric antigap, and permutational symmetry in the XY Z model

Dolf Huybrechts ,1,* Fabrizio Minganti ,2,† Franco Nori ,2,3,‡ Michiel Wouters,1,§ and Nathan Shammah 2,4,‖ 1Theory of Quantum & Complex Systems, University of Antwerp, B-2610 Wilrijk, Belgium 2Theoretical Quantum Physics Laboratory, RIKEN Cluster for Pioneering Research, Wako-shi, Saitama 351-0198, Japan 3Physics Department, The University of Michigan, Ann Arbor, Michigan 48109-1040, USA 4Quantum Technology Lab, Dipartimento di Fisica, Università degli Studi di Milano, 20133 Milano, Italy