Current noise in ac-driven nanoscale conductors.

The theory for current fluctuations in ac-driven transport through nanoscale systems is put forward. By use of a generalized, non-Hermitian Floquet theory we derive novel explicit expressions for the time-averaged current and the zero-frequency component of the power spectrum of current fluctuations. A distinct suppression of both the zero-frequency noise and the dc current occurs for suitably tailored ac fields. The relative level of transport noise, being characterized by a Fano factor, can selectively be manipulated by ac sources; in particular, it exhibits both characteristic maxima and minima near current suppression.