Frank Pollmann, MPIPKS, Dresden
Many-body localized (MBL) phases occur in isolated quantum systems when Anderson localization persists in the presence of finite interactions. It turns out that the entanglement is a very useful quantity to study these phases. First, we focus on the physics in the presence of strong disorder. For this we study the time evolution of simple (unentangled) initial states for a system of interacting spinless fermions in a one dimensional system. It is found that interactions induce a dramatic change in the propagation of entanglement. Second, we use the bipartite entanglement of excited eigenstates to pinpoint a phase transition from a localized to an extended phase in a random Ising chain with short ranged interactions. A characterizing property of the MBL phase is that the area law also applies to excited states. In one-dimensional systems, these states can be encoded efficiently using a matrix-product state representation.