Absence of Thermalization in Finite Isolated Interacting Floquet Systems

Understand

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.