# Effect of spin-orbit coupling on tunnelling escape of Bose-Einstein condensate

## TL;DR

This paper theoretically explores how spin-orbit coupling influences the quantum tunnelling escape of Bose-Einstein condensates, revealing phase-dependent behaviors and potential control mechanisms for atom lasers.

## Contribution

It introduces a detailed analysis of tunnelling dynamics in SO-coupled BECs across different phases, highlighting the suppressing effect of SO coupling on tunnelling.

## Key findings

- Tunnelling behavior varies with phase: continuous in single minimum and separated, pulsed in stripe.
- SO coupling suppresses tunnelling, nearly eliminating escape near phase transition.
- System tuning can control tunnelling, useful for atom laser applications.

## Abstract

We theoretically investigate quantum tunnelling escape of a spin-orbit (SO) coupled Bose-Einstein condensate (BEC) from a trapping well. The condensate is initially prepared in a quasi-one-dimensional harmonic trap. Depending on the system parameters, the ground state can fall in different phases --- single minimum, separated or stripe. Then, suddenly the trapping well is opened at one side. The subsequent dynamics of the condensate is studied by solving nonlinear Schr\"{o}dinger equations. We found that the diverse phases will greatly change the tunneling escape behavior of SO coupled BECs. In single minimum and separated phases, the condensate escapes the trapping well continuously, while in stripe phase it escapes the well as an array of pulses. We also found that SO coupling has a suppressing effect on the tunnelling escape of atoms. Especially, for BECs without inter-atom interaction, the tunnelling escape can be almost completely eliminated when the system is tuned near the transition point between single minimum and stripe phase. Our work thus suggests that SO coupling may be a useful tool to control the tunnelling dynamic of BECs, and potentially be applied in realization of atom lasers and matter wave switches.