Single-photon frequency down-conversion experiment
Hiroki Takesue · Physical Review A · 2010
We report a single-photon frequency down-conversion experiment. Using the difference frequency generation process in a periodically poled lithium niobate waveguide, we successfully observed the phase-preserved frequency down-conversion of a coherent pulse train with an average photon number per pulse of $<$$1$, from the $0.7$ $\ensuremath{\mu}$m visible wavelength band to the $1.3$ $\ensuremath{\mu}$m telecom band. We expect this technology to become an important tool for flexible photonic quantum networking, including the realization of quantum repeater systems over optical fiber using atom-photon entanglement sources for the visible wavelength bands.