Microwave-driven persistent currents in a nanoscale quantum ring

Time-dependent electron current through a nanoscale phase-coherent quantum ring with leads, coupled to reservoirs biased by a sinusoidal voltage, is studied. We argue that Floquet states in such samples, driven also by external time-periodic magnetic field, can be coherently manipulated. Some examples show that on-demand structures in the frequency domain, tunable by the joint action of the voltage bias and a microwave pumping, can be generated this way.