Relaxation dynamics in a strongly coupled Fermi superfluid

TL;DR

This paper explores the relaxation dynamics of a strongly coupled Fermi superfluid, revealing a wave of excitations in momentum space that leads to rapid equilibration after a sudden quench.

Contribution

It introduces a novel mechanism for relaxation in strongly coupled Fermi superfluids using D-brane models from string theory, highlighting wave propagation in momentum space.

Findings

Relaxation occurs rapidly after a quench, within a few quasiparticle gap oscillations.

A wave of excitation propagates from the Fermi surface to higher energies.

The mechanism is modeled using D-brane constructions from string theory.

Abstract

The key feature of time-dependent dynamics in a paired Fermi superfluid is the presence of a large number of independent degrees of freedom---the pairing amplitudes of fermions with different momenta. We argue that useful prototypes of this dynamics come from D-brane constructions of string theory. Using a specific example of that kind, we identify the mechanism by which a strongly coupled Fermi superfluid relaxes to equilibrium; it involves a wave of excitation in the momentum space, propagating from the Fermi surface towards the ultraviolet. For a sudden quench induced by a change in the fermion coupling, we find that the relaxation occurs rapidly, over only a few oscillations of the quasiparticle gap.