Dissipative quantum North-East-Center model: Steady-state phase diagram, universality and nonergodic dynamics

Year: 2026

Authors: Brighi P., Biella A.

Autors Affiliation: Univ Vienna, Fac Phys, Boltzmanngasse 5, A-1090 Vienna, Austria; Univ Trento, Pitaevskii BEC Ctr, CNR, INO, I-38123 Trento, Italy; Univ Trento, Dipartimento Fis, I-38123 Trento, Italy; Trento Inst Fundamental Phys & Applicat, INFN TIFPA, I-38123 Trento, Italy.

Abstract: In this work we study the dissipative quantum North-East-Center (NEC) model: a twodimensional spin-1/2 lattice subject to chiral, kinetically constrained dissipation and coherent quantum interactions. This model combines kinetic constraints and chirality at the dissipative level, implementing local incoherent spin flips conditioned by an asymmetric majority-vote rule. Through a cluster mean-field approach, we determine the steady-state phase diagram of the NEC model under different Hamiltonians, consistently revealing the emergence of two distinct phases, bistable and normal, across all cases considered. We further investigate the stability of the steady-state with respect to inhomogeneous fluctuations in both phases, showing the emergence of instabilities at finite wavevectors in the proximity of the phase transition. Next, we study the nonergodicity of the model in the bistable phase. We characterize the dynamics of minority islands of spins surrounded by a large background of spins pointing in the opposite direction. We show that in the bistable phase, the minority islands are always reabsorbed by the surrounding at a constant velocity, irrespectively of their size. Finally, we propose and numerically benchmark an equation of motion for the reabsorption velocity of the islands where thermal and quantum fluctuations act independently at linear order.

Journal/Review: SCIPOST PHYSICS

Volume: 20 (1)      Pages from: 19-1  to: 19-26

More Information: Funding information P. B. acknowledges support by the Austrian Science Fund (FWF) [Grant Agreement No. 10.55776/ESP9057324]. A. B. acknowledges financial support from the Provincia Autonoma di Trento and by the European Union \u2014 NextGeneration EU, within PRIN 2022, PNRR M4C2, Project TANQU 2022FLSPAJ [CUP B53D23005130006].
KeyWords: Complex
DOI: 10.21468/SciPostPhys.20.1.019