Direct Excitation of a Single Quantum Dot with Cavity-SPDC Photons.

The ability to generate mode-engineered single photons with the flexibility to efficiently interface with disparate quantum systems is of importance for building a quantum network. Here we report on the generation of such a customized, pulsed, heralded single photon source with a sub-GHz spectral bandwidth to mode match with Indium Arsenide quantum dots centered at 942 nm. The source is built with a type-II PPKTP down-conversion crystal embedded in a semi-confocal optical cavity and pumped with a 76 MHz repetition rate pulsed laser to emit collinear, polarization-correlated photon pairs synchronized with the emission of a single quantum dot. Finally, in order to demonstrate direct coupling, we use the mode-engineered cavity-SPDC single-photon source to resonantly excite an isolated single quantum dot. The temporal and spectral mode profile matching between the exciting photon and a two-level system is important for efficient coupling through direct excitation. This work lays a foundation for the efficient transfer of quantum states between distant nodes formed with single quantum dots through a direct excitation process.