Pair tunneling of two atoms out of a trap

TL;DR

This paper develops a simple theoretical model for the tunneling of two cold atoms out of a trap, considering both single-atom and pair tunneling, and compares predictions with recent experimental results.

Contribution

It introduces a novel theoretical framework that separately analyzes single-atom and pair tunneling in a two-atom system with attractive interactions.

Findings

Qualitative agreement with experimental tunneling rates

Derived effective equations for pair center-of-mass motion

Quantitative predictions of tunneling dependence on interaction strength

Abstract

A simple theory for the tunneling of two cold atoms out of a trap in the presence of an attractive contact force is developed. Two competing decay channels, respectively for single-atom and bound-pair tunneling, contribute independently to the decay law of the mean atom number in the trap. The single-atom tunneling rate is obtained through the quasiparticle wave function formalism. For pair tunneling an effective equation for the center-of-mass motion is derived, so the calculation of the corresponding tunneling rate is again reduced to a simpler one-body problem. The predicted dependence of tunneling rates on the interaction strength qualitatively agrees with a recent measurement of the two-atom decay time [G. Zuern, A. N. Wenz, S. Murmann, T. Lompe, and S. Jochim, arXiv:1307.5153].