Quantum Frequency Translation and Interference of Two Photons of Different Color
Michael G. Raymer, Hayden McGuinness, S. J. van Enk, Colin J. McKinstrie · 2011
Two photons having different colors can exhibit the Hong-Ou-Mandel interference effect if the usual beam splitter is replaced by Bragg scattering via four-wave mixing in an optical fiber, which acts as a frequency shifter.