Speaker
Prof.
Uwe-Jens Wiese
(Bern University)
Description
The real-time evolution of large open quantum spin systems, whose dynamics are entirely driven by dissipative couplings to an environment, is studied in two and three spatial dimensions. Dissipative processes with Hermitean quantum jump operators lead from the ordered phase of the Heisenberg or XY-model into a disordered phase at late times. The corresponding Lindblad equation is solved using an efficient cluster algorithm. The symmetries of the dissipative process determine the time scales that govern the approach towards equilibrium. One encounters slow equilibration if the dissipative process conserves any of the magnetization Fourier modes. The non-equilibrium transport of magnetization between a Heisenberg ferromagnet and an antiferromagnet, initially isolated
from each other in two separate parts of the volume, is also investigated. Finally, a cooling process with non-Hermitean quantum jump operators, which leads into a Bose-Einstein condensate of hard-core bosons as a dark state, is simulated with a worm algorithm, and the different time-scales that arise during equilibration are again investigated.
Primary author
Prof.
Uwe-Jens Wiese
(Bern University)
