SciPost Phys. 11, 040 (2021) ·
published 24 August 2021
The manipulation of many-body systems often involves time-dependent forces that cause unwanted heating. One strategy to suppress heating is to use time-periodic (Floquet) forces at large driving frequencies. For quantum spin systems with bounded spectra, it was shown rigorously that the heating rate is exponentially small in the driving frequency.
Recently, the exponential suppression of heating has also been observed in an experiment with ultracold atoms, realizing a periodically driven Bose-Hubbard model. This model has an unbounded spectrum and, hence, is beyond the reach of previous theoretical approaches. Here, we study this model with two semiclassical approaches valid, respectively, at large and weak interaction strengths. In both limits, we compute the heating rates by studying the statistical probability to encounter a many-body resonance, and obtain a quantitative agreement with the exact diagonalization of the quantum model. Our approach demonstrates the relevance of statistical arguments to Floquet perthermalization of interacting many-body quantum systems.
SciPost Phys. 5, 023 (2018) ·
published 14 September 2018
Scale invariance usually occurs in extended systems where correlation
functions decay algebraically in space and/or time. Here we introduce a new
type of scale invariance, occurring in the distribution functions of physical
observables. At equilibrium these functions decay over a typical scale set by
the temperature, but they can become scale invariant in a sudden quantum
quench. We exemplify this effect through the analysis of linear and non-linear
quantum oscillators. We find that their distribution functions generically
diverge logarithmically close to the stable points of the classical dynamics.
Our study opens the possibility to address integrability and its breaking in
distribution functions, with immediate applications to matter-wave
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