title: Topological Instabilities in ac-Driven Bosonic Systems.
abstract: Under nonequilibrium conditions, bosonic modes can become dynamically unstable with an exponentially growing occupation. On the other hand, topological band structures give rise to symmetry protected midgap states. In this Letter, we investigate the interplay of instability and topology. Thereby, we establish a general relation between topology and instability under ac driving. We apply our findings to create dynamical instabilities which are strongly localized at the boundaries of a finite-size system. As these localized instabilities are protected by symmetry, they can be considered as topological instabilities.
authors: Institut für Theoretische Physik, Technische Universität Berlin, Hardenbergstrasse 36, 10623 Berlin, Germany.
authors: G
authors: G
authors: Engelhardt
authors: Instituto de Ciencia de Materials de Madrid, CSIC, 28049 Madrid, Spain.
authors: M
authors: M
authors: Benito
authors: Instituto de Ciencia de Materials de Madrid, CSIC, 28049 Madrid, Spain.
authors: G
authors: G
authors: Platero
authors: Institut für Theoretische Physik, Technische Universität Berlin, Hardenbergstrasse 36, 10623 Berlin, Germany.
authors: T
authors: T
authors: Brandes