Production of heralded pure single photons from imperfect sources using cross-phase-modulation
Thomas R. Konrad, Michael Nock, Artur Scherer, Jürgen Audretsch · Physical Review A · 2006
Realistic single-photon sources do not generate single photons with certainty. Instead they produce statistical mixtures of photons in Fock states $\ensuremath{\mid}1⟩$ and vacuum (noise). We describe how to eliminate the noise in the output of the sources by means of another noisy source or a coherent state and cross-phase-modulation (XPM). We present a scheme that announces the production of pure single photons and thus eliminates the vacuum contribution. This is done by verifying a XPM-related phase shift with a Mach-Zehnder interferometer.