Symmetry-Protected Topological Order in Open Systems

This talk will discuss the robustness of symmetry protected topological (SPT) order to evolution by noisy channels. By studying the evolution of non-local string order parameters, we find that one-dimensional SPT order is destabilized by generic couplings to the environment as well as by couplings satisfying a weak symmetry condition that directly generalizes from closed systems. We introduce a stronger symmetry condition on channels that ensures SPT order is preserved.