Abstract
We compute the Floquet Hamiltonian for weakly interacting fermions subjected to a continuous periodic drive using a Floquet perturbation theory (FPT) with the interaction amplitude being the perturbation parameter. This allows us to address the dynamics of the system at intermediate drive frequencies , where is the amplitude of the kinetic term, is the drive frequency, and is the typical interaction strength between the fermions. We compute, for random initial states, the fidelity between wave functions after a drive cycle obtained using and that obtained using exact diagonalization (ED). We find that FPT yields a substantially larger value of compared to its Magnus counterpart for and . We use the obtained to study the nature of the steady state of an weakly interacting fermion chain; we find a wide range of which leads to subthermal or superthermal steady states for finite chains. The driven fermionic chain displays perfect dynamical localization for ; we address the fate of this dynamical localization in the steady state of a finite interacting chain and show that there is a crossover between localized and delocalized steady states. We discuss the implication of our results for thermodynamically large chains and chart out experiments which can test our theory.
2 More- Received 23 July 2020
- Revised 6 October 2020
- Accepted 20 November 2020
DOI:https://doi.org/10.1103/PhysRevB.102.235114
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