Berlin 2014 – wissenschaftliches Programm
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Q: Fachverband Quantenoptik und Photonik
Q 49: Quantum gases: Lattices I
Q 49.7: Vortrag
Donnerstag, 20. März 2014, 18:00–18:15, UDL HS2002
Interferometric measurement of many-body topological invariants in ultra cold quantum gases — •Fabian Grusdt1,2, Norman Yao2, Dmitry Abanin2,3, and Eugene Demler2 — 1Department of physics, research center OPTIMAS and graduate school MAINZ, TU Kaiserslautern — 2Physics Department, Harvard University — 3Perimeter Institute, Waterloo, Canada
We present a scheme for the direct detection of many-body topological invariants in ultra cold quantum gases in optical lattices. We generalize single-particle interferometric schemes developed for the detection of topologically non-trivial band structures [Atala et.al., Nature Physics 9, 795 (2013)] by coupling a spin-1/2 impurity to a (topological) excitation of an interacting many-body system. Performing Ramsey interferometry in combination with Bloch oscillations of the resulting composite particle allows to directly detect the many body-topological invariant. In particular we consider adiabatic Thouless pumps, which transport a quantized amount of particles across a one-dimensional lattice. In the presence of inter-atomic interactions this quantized current is given by a many-body Chern number, which can be measured using our protocol. These systems also support symmetry-protected topological phases, the invariants of which can as well be obtained from our protocol.