Work extraction in an isolated quantum lattice systems: Grand canonical and generalized Gibbs ensemble predictions*

We study work extraction in noninteracting and weakly interacting isolated fermionic quantum lattice systems in one dimension [1,2]. We extract work by quenching on-site potentials in a subsystem, letting the entire system equilibrate to the generalized Gibbs ensemble (GGE, noninteracting case) or to the Gibbs ensemble (GE, weakly interacting case), and returning to the initial parameters in the subsystem using a quasi-static process. We identify a class of quenches in both ensembles that does not produce entropy. Those quenches are proved to ensure maximal work extraction in the thermodynamic limit when thermalization occurs. We show that the same remains true in the presence of integrable dynamics that results in equilibration to the GGE [1]. We explore the use of emergent local Hamiltonians as a way to reduce the time taken by our protocol [2].

References:
[1] R. Modak and M. Rigol, Phys. Rev. E 95, 062145 (2017).
[2] R. Modak, L. Vidmar, and M. Rigol, Phys. Rev. E 96, 042155 (2017).