All-optically tunable buffer for single photons.

We demonstrate a photon buffer for quantum communication systems via a quantum frequency conversion-dispersion technique based on Bragg scattering four-wave mixing. The all-fiber setup is capable of imparting all-optical and continuously tunable delays onto single photons with minimal photon noise and absorption. Tunable delays up to 23 times the photon duration are demonstrated with on/off efficiencies as high as 55%.