Subdiffusion in wave packets with periodically kicked interactions

TL;DR

This paper investigates the quantum dynamics of a Bose gas with periodically kicked interactions, revealing that finite-duration kicks lead to subdiffusive wave packet spreading, contrasting with previously observed exponential spreading in delta-kick limits.

Contribution

It demonstrates that finite-duration kicks cause subdiffusive spreading in the system, highlighting the importance of kick duration in quantum dynamics of driven Bose gases.

Findings

Wave packet spreading is subdiffusive for finite-duration kicks.

Exponential spreading occurs only in the delta-kick limit.

Subdiffusion appears at relatively short times even for very short kicks.

Abstract

We study the quantum dynamics of a peculiar driven system, a Bose gas subjected to periodically kicked interactions. In the limit of infinitely short kicks, this system was recently shown to exhibit a fast exponential spreading of the wave function. Here we examine this problem for kicks or arbitrary duration and show that, in this case, the spreading is not exponential but rather subdiffusive at long time. This phenomenon stems from the competition between the kinetic and interaction energies within the kicks, which is absent in the limit of delta kicks. Our analysis further shows that the breakdown of exponential spreading occurs at relatively short times even for extremely short kicks, suggesting that, in practice, subdiffusion should be more the rule than the exception in this system.