Rudner, Mark

Monday May 6, 2013
Time: 16:15
Place: University of Basel, Physics Department, Lecture Hall 1
Host: Patrick Maletinsky

Quantum alchemy for the 21st century: creating topological states in trivial systems via time-dependent driving

Mark Rudner
Niels Bohr Institute, Copenhagen

Recently, many authors have begun to explore topological phenomena in periodically-driven systems of non-interacting particles. These phenomena are identified through analogies between the Floquet spectra of driven systems and the band structures of static Hamiltonians. Intriguingly, these works have revealed that the topological characterization of driven systems is richer than that of static systems. In particular, in driven systems in two dimensions (2D), robust chiral edge states can appear even though the Chern numbers of all the bulk Floquet bands are zero. In this talk I will give an introduction to this emerging field, and elucidate the crucial distinctions between static and driven 2D systems, through simple easy-to-follow examples.  I will then show how we construct a new topological invariant, that yields the correct edge state structure in the driven case.  Complementary formulations in the time and frequency domains afford additional insight into the origins of the "anomalous" spectra which arise in driven systems. Time permitting, possible realizations of these phenomena in solid state and cold atomic systems will be discussed.