We demonstrate quantum frequency translation of single photons via four-wave-mixing Bragg scattering using a liquid nitrogen cooled dispersion-shifted fiber. We achieve 80% photon conversion efficiency with less than 0.001 noise photons per 5ns gate.
We experimentally demonstrate frequency translation of a non-classical optical field by Bragg-scattering four-wave mixing, driven by orthogonally polarized pump pulses in a birefringent optical fiber. Heralded single photons are up- and down-translated by 6.8 THz between bands at 688.1 nm and 678.2 nm, each with efficiency > 97%. The input and output spectral shape and bandwidth show negligible modulation. Second-order auto-correlation measurements of the 678.2 nm and 688.1 nm fields at maximum conversion yield values of 0.0302 ± 0.0005 and 0.028 ± 0.001, respectively, compared with the input second-order correlation of 0.026 ± 0.001; this indicates that the frequency translation process preserves the non-classical nature of the field. The high efficiency, broad bandwidth, and low noise render this scheme useful for quantum networks and sources.
The authors consider, experimentally and theoretically, the quantum frequency translation (i.e., noiseless conversion) of quantum states of light, including single-photon states. This process is useful for allowing quantum optical systems (atoms, ions, cavities, fibers, detectors) operating at different wavelengths to communicate with each other. The authors recently developed the process of frequency translation in optical fiber through use of the Bragg scattering four-wave mixing process. The high nonlinearity and the ability to control dispersion in photonic crystal fiber (PCF) enable efficient translation between nearby photon channels within the visible to-near-infrared spectral range, useful in quantum networks. This offers an important advantage compared with frequency translation using second-order nonlinear optical crystals, which limits the translation process to widely separated frequencies only.