Symmetries in open quantum systems

Abstract

Controlling nonequilibrium properties of quantum systems holds the key to many promising quantum technologies. Here I'll introduce the power of symmetry as a resource to manipulate quantum Non-Equilibrium Steady States (NESS). In the first part of the talk I'll introduce some preliminaries about the role of symmetries in steady state quantum transport and how this concept can be exploited to control quantum currents. I’ll introduce a novel scheme to identify symmetries in presence of a weak disorder. The scheme will identify key signatures in the dynamical quantum currents that are unique to symmetric systems and give us vital information about the underlying molecular symmetries. In the second part, I'll introduce magnetic fields that can be used to break the open system symmetries in single-particle simple cubic lattices. In the absence of a magnetic field the open system symmetries are preserved and help modulate the NESS based on the symmetry decomposition of the initial state. The presence of a magnetic field breaks symmetries in preferential directions with all symmetries being broken only in the presence of an anisotropic field. These results demonstrate the importance of symmetry not only as an organizing principle in physics but also as a tool to control quantum systems.