Vortex dipole precession in a Fermi superfluid with Rashba spin-orbit coupling

TL;DR

This paper derives an analytical model describing how Rashba spin-orbit coupling causes vortex dipole precession in a Fermi superfluid, providing insights into vortex dynamics relevant for topological quantum systems.

Contribution

It provides the first closed-form solution for vortex dipole dynamics in a Fermi superfluid with Rashba spin-orbit coupling, including the effects of transient superfluid behavior.

Findings

Rashba SO coupling induces vortex dipole precession.

The superfluid's gap decays over time, indicating a transient state.

Analytic solution aids future studies of vortex braiding and topological states.

Abstract

We present a closed-form expression for the time dynamics of a balanced Fermi superfluid with s-wave pairing and Rashba spin-orbit (SO) coupling. Solving the associated self-consistency conditions for an initial number density given by a Gaussian and an initial gap containing a vortex dipole, we show that Rashba SO coupling results in precession of the vortex dipole. The integrated self-consistent gap decays as a function of time, characterising a "transient Fermi superfluid". Our analytic solution forms a starting point for studies of vortex dynamics -- in particular braiding of Majorana fermions -- in Fermi superfluids in the presence of spin population imbalance and two-dimensional SO coupling, which are both required to realize a topological atomic Fermi gas in experiments.