Three-level mixing and dark states in transport through quantum dots

We consider theoretically the transport through the double quantum dot structure of the recent experiment of Payette [Phys. Rev. Lett. 102, 026808 (2009)] and calculate stationary current and shot noise. Three-level mixing gives rise to a pronounced current-suppression effect, the character of which changes markedly with bias direction. We discuss these results in connection with the dark states of coherent population trapping in quantum dots.