2017/06/30 by Bo Song, Long Zhang, Chengdong He +5 · 1 citation
Physics and Astronomy · #cond-mat.quant-gas #cond-mat.str-el #quant-ph
paper · pdf · doi:10.1126/sciadv.aao4748
published as Science Advances 4, eaao4748 (2018) · 22 pages, 5 figures (main text); 10 pages, 6 figures (supplementary)
arxiv created 2018/08/29 · arxiv updated 2018/08/30
Symmetry plays a fundamental role in understanding complex quantum matter, particularly in classifying topological quantum phases, which have attracted great interests in the recent decade. An outstanding example is the time-reversal invariant topological insulator, a symmetry-protected topological (SPT) phase in the symplectic class of the Altland-Zirnbauer classification. We report the observation for ultracold atoms of a noninteracting SPT band in a one-dimensional optical lattice and study quench dynamics between topologically distinct regimes. The observed SPT band can be protected by a magnetic group and a nonlocal chiral symmetry, with the band topology being measured via Bloch states at symmetric momenta. The topology also resides in far-from-equilibrium spin dynamics, which are predicted and observed in experiment to exhibit qualitatively distinct behaviors in quenching to trivial and nontrivial regimes, revealing two fundamental types of spin-relaxation dynamics related to bulk topology. This work opens the way to expanding the scope of SPT physics with ultracold atoms and studying nonequilibrium quantum dynamics in these exotic systems.