Energy Dynamics of a Nonequilibrium Unitary Fermi Gas

TL;DR

This study explores how energy is injected and redistributed in a nonequilibrium unitary Fermi gas through trap modulation, revealing oscillatory energy dynamics and the impact of anharmonicity.

Contribution

It demonstrates precise measurement of energy evolution in a driven nonequilibrium Fermi gas and validates the dynamic virial theorem in this context.

Findings

Energy and internal energies increase with modulation time and oscillate out of phase.

Large modulation amplitudes reduce energy-injection efficiency due to trap anharmonicity.

Energy evolution matches predictions of the dynamic virial theorem.

Abstract

We investigate the energy dynamics of a unitary Fermi gas driven away from equilibrium. The energy is injected into the system by periodically modulating the trapping potential of a spherical unitary Fermi gas, and due to the existence of SO(2,1) symmetry, the breathing mode is excited without dissipation. Through the long-lived breathing oscillation, we precisely measure the energy evolution of the nonequilibrium system during the trap modulation. We find the trapping potential and internal energies increase with modulation time and simultaneously oscillate nearly $\textrm{180}^{\textrm{o}}$ out of phase. At large modulation amplitudes, the energy-injection efficiency is strongly reduced due to the trap anharmonicity. Unlike the equilibrium system, the measured energy evolution agrees well with predictions of the dynamic virial theorem. Our work provides valuable insights into the energy injection and redistribution in a non-equilibrium system, paving a way for future investigations of nonequilibrium thermodynamics.