%0 Journal Article %J Physical Review B %D 2018 %T Absence of Thermalization in Finite Isolated Interacting Floquet Systems %A Karthik Seetharam %A Paraj Titum %A Michael Kolodrubetz %A Gil Refael %X

Conventional wisdom suggests that the long time behavior of isolated interacting periodically driven (Floquet) systems is a featureless maximal entropy state characterized by an infinite temperature. Efforts to thwart this uninteresting fixed point include adding sufficient disorder to realize a Floquet many-body localized phase or working in a narrow region of drive frequencies to achieve glassy non-thermal behavior at long time. Here we show that in clean systems the Floquet eigenstates can exhibit non-thermal behavior due to finite system size. We consider a one-dimensional system of spinless fermions with nearest-neighbor interactions where the interaction term is driven. Interestingly, even with no static component of the interaction, the quasienergy spectrum contains gaps and a significant fraction of the Floquet eigenstates, at all quasienergies, have non-thermal average doublon densities. We show that this non-thermal behavior arises due to emergent integrability at large interaction strength and discuss how the integrability breaks down with power-law behavior in system size.

%B Physical Review B %V 97 %P 014311 %8 2018/01/29 %G eng %U https://journals.aps.org/prb/abstract/10.1103/PhysRevB.97.014311 %N 1 %R 10.1103/PhysRevB.97.014311