Polaronic effects in electron shuttling

Shuttle-like mechanism of electron transport through a single level vibrating quantum dot is considered in the regime of strong electromechanical coupling. It is shown that the increment of shuttle instability is a nonmonotonic function of the driving voltage. The interplay of two oppositely acting effects - vibron-assisted electron tunneling and polaronic blockade - results in oscillations of the increment on the energy scale of vibron energy.