Interacting ultracold atomic kicked rotors: dynamical localization ?

TL;DR

This paper investigates how contact interactions between two quantum kicked rotors influence dynamical localization, showing that localization persists for the center-of-mass momentum but is destroyed for the relative momentum due to non-analytic effects.

Contribution

It reveals that contact interactions cause a non-analytic impact on the relative momentum evolution, destroying dynamical localization there while preserving it for the center-of-mass momentum.

Findings

Dynamical localization is preserved for the center-of-mass momentum.

Dynamical localization is destroyed for the relative momentum with any nonzero interaction.

Interaction induces a power-law decay in the amplitudes for relative momentum.

Abstract

We study the fate of dynamical localization of two quantum kicked rotors with contact interaction. This interaction mimics experimental realizations with ultracold atomic gases. Dynamical localization for a single rotor takes place in momentum space. The contact interaction affects the evolution of the relative momentum $k$ of a pair of interacting rotors in a non-analytic way. Consequently the evolution operator $U$ is exciting large relative momenta with amplitudes which decay only as a power law $1/k^4$. This is in contrast to the center-of-mass momentum $K$ for which the amplitudes excited by $U$ decay superexponentially fast. Therefore dynamical localization is preserved for the center-of-mass momentum, but destroyed for the relative momentum for any nonzero strength of interaction.