Spin-cavity interactions between a quantum dot molecule and a photonic crystal cavity.

The integration of InAs/GaAs quantum dots into nanophotonic cavities has led to impressive demonstrations of cavity quantum electrodynamics. However, these demonstrations are primarily based on two-level excitonic systems. Efforts to couple long-lived quantum dot electron spin states with a cavity are only now succeeding.

Leveraging crystal anisotropy for deterministic growth of InAs quantum dots with narrow optical linewidths.

Crystal growth anisotropy in molecular beam epitaxy usually prevents deterministic nucleation of individual quantum dots when a thick GaAs buffer is grown over a nanopatterned substrate. Here, we demonstrate how this anisotropy can actually be used to mold nucleation sites for single dots on a much thicker buffer than has been achieved by conventional techniques. This approach greatly suppresses the problem of defect-induced line broadening for single quantum dots in a charge-tunable device, giving state-of-the-art optical linewidths for a system widely studied as a spin qubit for quantum information.