Structure of non-equilibrium quantum phase transitions

KTH/Nordita/SU seminar in Theoretical Physics

Wednesday 15 February 2017
from 11:00
to 12:00 at
A4:1069

Speaker :

Jonas Larson (Fysikum SU)

Abstract :

The steady state of a driven-dissipative system does not have to attain a thermal equilibrium. By carefully monitoring the coupling between the system and its environment, the steady state may indeed become non-trivial, like for example highly entangled, topological, squeezed, and so on. Upon changing some model parameter the steady state may even show non-analytic behaviours, reminiscent of what is found for the ground state at critical points that marks a continuous phase transition.

In this talk I consider such a case, and demonstrate that this non-equilibrium phase transition falls outside the Landau paradigm for phase transition. The critical properties are however characterized by critical exponents, but there is no spontaneous symmetry breaking involved with the transition. Thereby, just like topological phase transitions, this is another example of criticality that cannot be understood from the text-book Landau theory.