Quantum dot coupled to a suspended-beam mechanical resonator: From the unresolved- to the resolved-sideband regime

We present experiments in which self-assembled InAs quantum dots are coupled to a thin, suspendedbeam GaAs resonator. The quantum dots are driven resonantly and the resonance fluorescence is detected. The narrow quantum dot linewidths, just a factor of 3 larger than the transform limit, result in a high sensitivity to the mechanical motion. We show that one quantum dot couples to eight mechanical modes spanning a frequency range from 30 to 600 MHz: one quantum dot provides an extensive characterization of the mechanical resonator. The coupling spans the unresolved-sideband to the resolved-sideband regimes. Finally, we present the first detection of thermally driven phonon sidebands (at 4.2 K) in the resonance-fluoresence spectrum.