Goos-H\"anchen shifts in spin-orbit-coupled cold atoms

TL;DR

This paper investigates how spin-orbit coupling in cold atoms affects the Goos-H"anchen shift during total internal reflection, revealing large positive and negative shifts due to evanescent state interactions.

Contribution

It introduces the concept of oscillating evanescent states in cold atoms with spin-orbit coupling and their impact on the GH effect, a novel mechanism not previously explored.

Findings

Large positive and negative GH shifts observed.

Dependence of GH shift on incident angle, energy, and potential height.

Identification of two types of evanescent states influencing TIR.

Abstract

We consider a matter wave packet of cold atom gas impinging upon a step potential created by the optical light field. In the presence of spin-orbit (SO) coupling, the atomic eigenstates contain two types of evanescent states, one of which is the ordinary evanescent state with pure imaginary wave vector while the other possesses complex wave vector and is recognized as oscillating evanescent state. We show that the presence and interplay of these two types of evanescent states can give rise to two different mechanisms for total internal reflection (TIR), and thus lead to unusual Goos-H\"anchen (GH) effect. As a result, not only large positive but also large negative GH shift can be observed in the reflected atomic beam. The dependence of the GH shift on the incident angle, energy and height of the step potential is studied numerically.