2019/08/31 by David J. Luitz, Roderich Moessner, S. L. Sondhi +1 · 1 citation
Physics and Astronomy · #cond-mat.dis-nn #quant-ph
paper · pdf · doi:10.1103/physrevx.10.021046
published as Phys. Rev. X 10, 021046 (2020) · v2- published version; discussions expanded and clarified
arxiv created 2020/11/08 · arxiv updated 2020/11/10
While a clean driven system generically absorbs energy until it reaches `infinite temperature', it may do so very slowly exhibiting what is known as a prethermal regime. Here, we show that the emergence of an additional approximately conserved quantity in a periodically driven (Floquet) system can give rise to an analogous long-lived regime. This can allow for non-trivial dynamics, even from initial states that are at a high or infinite temperature with respect to an effective Hamiltonian governing the prethermal dynamics. We present concrete settings with such a prethermal regime, one with a period-doubled (time-crystalline) response. We also present a direct diagnostic to distinguish this prethermal phenomenon from its infinitely long-lived many-body localised cousin. We apply these insights to a model of the recent NMR experiments by Rovny et al., [Phys. Rev. Lett. 120, 180603 (2018)] which, intriguingly, detected signatures of a Floquet time crystal in a clean three-dimensional material. We show that a mild but subtle variation of their driving protocol can increase the lifetime of the time-crystalline signal by orders of magnitude.