Coalescence of Single Photons Emitted by Disparate Single Photon   Sources: The Example of InAs Quantum Dots and Parametric Down-Conversion   Sources
  Single photons produced by fundamentally dissimilar physical processes will in general not be indistinguishable. We show how photons produced from a quantum dot and by parametric down-conversion in a nonlinear crystal can be manipulated to be indistinguishable. The measured two-photon coalescence probability is 16%, and is limited by quantum-dot decoherence. Temporal filtering to the quantum dot coherence time and accounting for detector time response increases this to 61% while retaining 25% of the events. This technique can connect different elements in a scalable quantum network. 
Sergey V. Polyakov, Andreas Muller, Edward B. Flagg, Alex Ling,   Natalia Borjemscaia, Edward Van Keuren, Alan Migdall, and ...
quant-ph