Periodically and Quasi-periodically Driven Dynamics of Bose-Einstein Condensates

TL;DR

This paper investigates the quantum dynamics of Bose-Einstein condensates under periodic and quasi-periodic modulation of the scattering length, revealing phase boundaries and complex excitation patterns including Hofstadter butterfly analogs.

Contribution

It introduces a detailed analysis of heating and non-heating phases in driven BECs with new protocols and visualizes their spectral structures.

Findings

Identification of phase boundaries between heating and non-heating regimes.

Discovery of Hofstadter butterfly-like spectral patterns in driven BECs.

Finite measure non-heating regimes in sine-wave quasi-periodic modulation.

Abstract

We study the quantum dynamics of Bose-Einstein condensates when the scattering length is modulated periodically or quasi-periodically in time within the Bogoliubov framework. For the periodically driven case, we consider two protocols where the modulation is a square-wave or a sine-wave. In both protocols for each fixed momentum, there are heating and non-heating phases, and a phase boundary between them. The two phases are distinguished by whether the number of excited particles grows exponentially or not. For the quasi-periodically driven case, we again consider two protocols: the square-wave quasi-periodicity, where the excitations are generated for almost all parameters as an analog of the Fibonacci-type quasi-crystal; and the sine-wave quasi-periodicity, where there is a finite measure parameter regime for the non-heating phase. We also plot the analogs of the Hofstadter butterfly for both protocols.