Coherent Control of an Optical Quantum Dot Using Phonons and Photons

TL;DR

This paper demonstrates coherent control of InAs quantum dot qubits using phonons and photons, revealing new optomechanical control techniques and potential for quantum transduction.

Contribution

It introduces experimental methods for controlling quantum dot populations with engineered optical pulses and mechanical motion, advancing quantum optomechanics.

Findings

Controlled QD population dynamics with optical and mechanical stimuli

Enhanced photon scattering via mechanically assisted processes

Spectral analysis of scattering channels matches quantum calculations

Abstract

Genuine quantum-mechanical effects are readily observable in modern optomechanical systems comprising bosonic ("classical") optical resonators. Here we describe unique features and advantages of optical two-level systems, or qubits, for optomechanics. The qubit state can be coherently controlled using 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, at moderate acoustic drive strengths, we demonstrate the potential of this technique to maximize fidelity in quantum microwave-to-optical transduction. Specifically, we tailor the scheme so that mechanically assisted photon scattering is enhanced over the direct detuned photon scattering from the QD. Spectral analysis reveals distinct scattering channels related to Rayleigh scattering and luminescence in our pulsed excitation measurements which lead to time-dependent scattering spectra. Quantum-mechanical calculations show good agreement with our experimental results, together providing a comprehensive description of excitation, scattering and emission in a coupled QD-phonon optomechanical system.