Deterministic assembly of a charged-quantum-dot-micropillar cavity device

Quantum-dot-based spin-photon interfaces are highly sought systems to implement deterministic photon-photon gates as well as to generate photonic cluster states. This requires mastering the technological challenge of fully controlling the coupling of a charged quantum dot to a cavity mode. Here, we report on a set of technological and experimental developments that allows doing so. The first ingredient consists in combining the in situ lithography technique, which allows a deterministic spatial and spectral coupling of the emitter to a pillar cavity mode, with a preidentification of the quantum dot charge states, using spectral fingerprints. The second ingredient relies on the design of an asymmetric tunneling barrier to inject the carrier in the quantum dot and an optical control of the charge occupation probability. We show that we can ensure both a high occupation probability of the charge in the quantum dot, reaching 91±1%, and an optimal coupling to the cavity mode, resulting in a single-photon source combining a highly polarized brightness of 33±5% with both a high purity (g(2)(0)=1.6±0.4%) and indistinguishability (97±0.4%) of the single photons.