Suppression and Control of Pre-thermalization in Multi-component Fermi Gases Following a Quantum Quench

TL;DR

This paper explores how initial conditions and symmetry-breaking interactions influence pre-thermalization in multi-component Fermi gases after a quantum quench, revealing conditions for its suppression and stabilization.

Contribution

It provides a detailed analysis of the role of initial states and symmetry-breaking in controlling pre-thermalization in alkaline-earth multi-component Fermi gases.

Findings

Suppression of pre-thermalization depends on initial population imbalance and number of components.

Breaking SU(N) symmetry alone does not necessarily suppress pre-thermalization.

Conditions for stabilizing pre-thermal states are identified for N ≥ 4.

Abstract

We investigate the mechanisms of control and suppression of pre-thermalization in $N$-component alkaline earth gases. To this end, we compute the short-time dynamics of the instantaneous momentum distribution and the relative population for different initial conditions after an interaction quench, accounting for the 11 peffect of initial interactions. We find that switching on an interaction that breaks the SU$(N)$ symmetry of the initial Hamiltonian, thus allowing for the occurrence of spin-changing collisions, does not necessarily lead to a suppression of pre-thermalization. However, the suppression will be most effective in the presence of SU$(N)$-breaking interactions provided the number of components $N \ge 4$ and the initial state contains a population imbalance that breaks the SU$(N)$ symmetry. We also find the conditions on the imbalance initial state that allow for a pre-thermal state to be stabilized for a certain time. Our study highlights the important role played by the initial state in the pre-thermalization dynamics of multicomponent Fermi gases. It also demonstrates that alkaline-earth Fermi gases provide an interesting playground for the study and control of pre-thermalization.