Mainz 2017 – scientific programme
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Q: Fachverband Quantenoptik und Photonik
Q 52: Quantum Gases: Fermions II
Q 52.1: Talk
Thursday, March 9, 2017, 14:30–14:45, P 204
Observation of a dynamical topological phase transition — •Benno Rem1, Nick Fläschner1, Dominik Vogel1, Matthias Tarnowski1, Dirk-Sören Lühmann1, Markus Heyl2, Jan Budich3, Ludwig Mathey1, Klaus Sengstock1, and Christof Weitenberg1 — 1ILP, ZOQ, CUI, Universität Hamburg — 2Physik Department, TU München — 3IQOQI, ITP, Universität Innsbruck
Topological phases are characterized by a non-local order and constitute a exotic form of matter. The paradigmatic Haldane model on a hexagonal lattices features topologically distinct phases characterized by the Chern number. Recently, quenches in such models have attracted particular attention and it was pointed out that while a Hall response builds up dynamically, the Chern number of the wave function cannot change across the quench. Instead the dynamical evolution will feature Fisher zeros in the Loschmidt amplitude, which give rise to what is called a dynamical phase transition. Here, we experimentally study this dynamical evolution using a time- and momentum-resolved state tomography for spin-polarized fermionic atoms in driven optical lattices [1]. At a critical time after a sudden quench, we observe the appearance, movement and annihilation of dynamical vortices in momentum space [2]. We identify them as the Fisher zeros, which signal the dynamical phase transition. Our results pave the way to a search of topological quantities in non-equilibrium dynamics.
N. Fläschner, et al., Science 352, 1091 (2016)
N. Fläschner, et al., arXiv:1608.05616 (2016)