Ultracold collision in the presence of synthetic spin-orbit coupling

TL;DR

This paper provides an analytic framework for understanding how isotropic Rashba spin-orbit coupling fundamentally alters ultracold fermion collisions, affecting threshold behavior and leading to preferred scattering into lower-energy helicity states.

Contribution

It offers the first analytic description of ultracold collisions with Rashba spin-orbit coupling, revealing significant modifications to collision dynamics even at weak coupling.

Findings

Ultracold collision behavior is significantly modified by spin-orbit coupling.

Particles tend to scatter into lower-energy helicity states.

Parity breaking leads to spontaneous emergence of handedness.

Abstract

We present an analytic description of ultracold collision between two spin-$\frac{1}{2}$ fermions with isotropic spin-orbit coupling of the Rashba type. We show that regardless of how weak the spin-orbit coupling may be, the ultracold collision at sufficiently low energies is significantly modified, including the ubiquitous Wigner threshold behavior. We further show that the particles are preferably scattered into the lower-energy helicity state due to the break of parity conservation, thus establishing interaction with spin-orbit coupling as one mechanism for the spontaneous emergence of handedness.