Quantum light generation with a semiconductor quantum dot

Abstract

We discuss recent progress using the radiative emission of single quantum dots as a triggered source of both single photons, and photon pairs displaying polarization entanglement. Excitation of a quantum dot with two electrons and two holes leads to the emission of a pair of photons. We show that, provided the spin splitting of the intermediate exciton state in the decay is erased, the photon pair is emitted in an entangled polarization state. Using quantum dots to generate quantum light has the advantage of allowing a robust and compact source to be realised with contacts for electrical injection. A cavity may be integrated into the semiconductor structure to enhance the photon collection efficiency and control the recombination dynamics. We detail a process to form a sub-micron current aperture within the device, allowing single quantum dots to be addressed electrically.