Heidelberg 2015 – scientific programme
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Q: Fachverband Quantenoptik und Photonik
Q 5: Quantum Gases: Bosons I
Q 5.6: Talk
Monday, March 23, 2015, 12:45–13:00, P/H2
Experimental reconstruction of Wilson loops in a honeycomb lattice — •Martin Reitter1,2, Tracy Li1,2, Lucia Duca1,2, Eugene Demler3, Manuel Endres3, Immanuel Bloch1,2, Monika Schleier-Smith4, and Ulrich Schneider1,2 — 1Ludwig-Maximilians-Universität, München, DE — 2MPQ, Garching, DE — 3Harvard University, Cambridge, USA — 4Stanford University, Palo Alto, USA
A wide range of many-body phenomena, such as the integer quantum Hall effect and the existence of robust conducting edge states in topological insulators, arise due to the topological properties of the energy bands of a solid. For a single band, these properties can be probed using adiabatic Berry phases. For multiple bands, this information is encoded in the eigenvalues of Wilson loops, which are non-Abelian generalizations of Berry phases. We present an experimental reconstruction of the Wilson loop using Bloch oscillations in a graphene-like optical lattice. Combined with existing methods, this allows for the full characterization of the geometric structure of the bands and the reconstruction of, e.g., the Z2 invariant, which cannot be extracted from Berry phase measurements alone.