Higgs mode in the quench dynamics of a confined ultracold Fermi gas in the BCS regime

TL;DR

This paper theoretically investigates the Higgs amplitude mode in a confined ultracold Fermi gas after a quench, revealing characteristic damped oscillations and irregular dynamics linked to system parameters.

Contribution

It provides a detailed analysis of the Higgs mode dynamics in confined Fermi gases, comparing full nonlinear solutions with linearized approximations to understand transition times and resonance effects.

Findings

Damped oscillations of the Higgs mode are observed after a quench.

Transition from damped to irregular dynamics depends on system parameters.

Resonant and off-resonant systems exhibit distinguishable behaviors.

Abstract

The Higgs amplitude mode of the order parameter of an ultracold confined Fermi gas in the BCS regime after a quench of the coupling constant is analyzed theoretically. Characteristic features are a damped oscillation which at a certain transition time changes into a rather irregular dynamics. We compare the numerical solution of the full set of nonlinear equations of motion for the normal and anomalous Bogoliubov quasiparticle excitations with a linearized approximation. In doing so the transition time as well as the difference between resonant systems, i.e., systems where the Fermi energy is close to a subband minimum, and off-resonant systems can be well understood and traced back to the system and geometry parameters.