Coherent Control of an Optical Quantum Dot Using Phonons and Photons

Genuine quantum-mechanical effects are readily observable in modern optomechanical systems comprising bosonic (``classical") optical resonators. Such systems have enabled laser-cooling of mesoscopic objects, generation of squeezed light, and the conversion of photons between microwave and optical modes. Here we demonstrate unique advantages of optical two-level systems, or qubits, for optomechanics. The qubit state can be coherently controlled using an immense variety of driving schemes including both phonons and resonant or detuned photons. We experimentally demonstrate this using charge-controlled InAs quantum dots (QDs) in surface-acoustic-wave resonators. Time-correlated single-photon counting measurements reveal the control of QD population dynamics using engineered optical pulses and mechanical motion. As a first example, we show how this can improve signal-to-background scattering in microwave-to-optical transduction processes. Specifically, we tailor the scheme so that mechanically assisted photon scattering is enhanced over the direct detuned photon scattering from the optical system. These differences are greatly amplified by strategic temporal pulse shaping. Quantum-mechanical calculations show good agreement with our experimental results and provide guidance for adapting these schemes to small phonon occupancies relevant for microwave-to-optical quantum transduction.