Prethermal Fragmentation in a Periodically Driven Fermionic Chain

We study a fermionic chain with nearest-neighbor hopping and density-density interactions, where the nearest-neighbor interaction term is driven periodically. We show that such a driven chain exhibits prethermal strong Hilbert space fragmentation (HSF) in the high drive amplitude regime at specific drive frequencies omega(*)(m). This constitutes the first realization of HSF for out-of-equilibrium systems. We obtain analytic expressions of omega(*)(m) using a Floquet perturbation theory and provide exact numerical computation of entanglement entropy, equal-time correlation functions, and the density autocorrelation of fermions for finite chains. All of these quantities indicate clear signatures of strong HSF. We study the fate of the HSF as one tunes away from omega(*)(m) and discuss the extent of the prethermal regime as a function of the drive amplitude.

Automated summary

We study a fermionic chain with driven nearest-neighbor interaction and find that it exhibits prethermal strong Hilbert space fragmentation (HSF) at specific drive frequencies omega(*)(m) and high drive amplitudes. This is the first realization of strong HSF for out-of-equilibrium systems. We derive analytic expressions for omega(*)(m) using Floquet perturbation theory and numerically compute entanglement entropy, equal-time correlation functions, and density autocorrelation of fermions. All these quantities demonstrate clear signatures of strong HSF. We also investigate the fate of HSF as one deviates from omega(*)(m) and discuss the extent of the prethermal regime as a function of the drive amplitude.