Ground-state cooling of a nanomechanical resonator with a triple quantum dot via quantum interference

Abstract

We employ double quantum interference to propose a ground-state cooling scheme for a nanomechanical resonator coupled to a triple quantum dot (TQD), of which the third dot is driven by a microwave field. In our scheme, the carrier transition is diminished by the destructive interference (the occurrence of a dark state) arising from the coherent tunnelings of electrons among the three dots. Furthermore, the additional transition induced by the microwave field enables the system to possess double quantum interference effect. Under certain conditions, the processes which might increase one phonon through the blue sideband transitions are prohibited due to the double destructive interference analog to double electromagnetically induced transparency mechanism. Thus, both the carrier and blue sideband transitions are canceled. The cooling process occurs when the electron trapped in the dark state absorbs one phonon of the resonator through the transition from the dark state to the bright state and then to the excited state and finally tunnels to the drain. As a result, the phonon occupation can be reduced to zero in the ideal case and the resonator can be cooled down to its ground state with high efficiency even when the dephasing of the TQD is present.