Increasing photocell power by quantum coherence induced by external source

We show that photocell power can be substantially enhanced by quantum coherence in the model proposed by [M. O. Scully Phys. Rev. Lett. 104, 207701 (2010)]. Here coherence is induced by an external microwave drive. We show that although such coherence requires an extra energy input, the amount of extra input power can be much smaller than produced enhancement of the photovoltaic power. We demonstrate that for certain parameters power enhancement is governed by quantum coherence and is not just a result of population transfer due to the driving field. This corroborates and extends the earlier work of Scully.