Control of dynamical localization in atom-optics kicked rotor

TL;DR

This paper demonstrates a method to enhance and control dynamical localization in an atom-optics kicked rotor system by flipping the kick sequence, leading to a mix of diffusion and localization effects.

Contribution

It introduces a novel modification of the kick sequence involving half Talbot time evolution to control localization in the quantum kicked rotor system.

Findings

Enhanced localization observed with modified kick sequence

Localized states exhibit non-exponential wave function profiles

Experimental results agree with numerical simulations

Abstract

Atom-optics kicked rotor represents an experimentally realizable version of the paradigmatic quantum kicked rotor system. After a short initial diffusive phase the cloud settles down to a stationary state due to the onset of dynamical localization. In this work we realise an enhancement of localization by modification of the kick sequence. We experimentally implement the modification to this system in which the sign of the kick sequence is flipped by allowing for a free evolution of the wavepackets for half the Talbot time after every $M$ kicks. Depending on the value of $M$, this modified system displays a combination of enhanced diffusion followed by asymptotic localization. This is explained as resulting from two competing processes -- localization induced by standard kicked rotor type kicks, and diffusion induced by half Talbot time evolution. The evolving states display a localized but non-exponential wave function profiles. This provides another route to quantum control in kicked rotor class of systems. The numerical simulations agree well with the experimental results.