Generation of time-bin entangled photon pairs using a quantum-dot cavity system

We present a scheme to realize a deterministic solid state source of time-bin entangled photon pairs using cavity-assisted stimulated Raman adiabatic passage (STIRAP) in a single quantum dot. The quantum dot is embedded inside a semiconductor cavity, and the interaction of a coherent superposition of two temporally separated input pulses and the cavity mode leads to a two-photon Raman transition, which produces a time-bin entangled photon pair through the biexciton-exciton cascade. We show that the entanglement of the generated state can be measured using triple coincidence detection, and the degree of entanglement is quantified as the visibility of the interference. We also discuss the effect of pure dephasing on entanglement of the generated photon pair. Pronounced interference visibility values of greater than 1/sqrt{2} are demonstrated in triple coincidence measurement using experimentally achievable parameters, thus demonstrating that the generated photons are suitable for applications with Bell's inequality violation and quantum cryptography.