Here we demonstrate adiabatic wavelength conversion at the single photon level with very low noise and high efficiency. This result is expected to enable wavelength conversion in future quantum optical systems.
Adiabatic wavelength conversion is experimentally demonstrated at a single photon power-level using an integrated silicon ring resonator. This approach allows conversion of a photon to arbitrary wavelengths with no energy or phase matching constraints. The conversion is inherently low-noise and efficient with greater than 10% conversion efficiencies for wavelength changes up to 0.5 nm, more than twenty times the resonators line-width. The observed wavelength change and efficiency agrees well with theory and bright coherent light demonstrations. These results will enable integrated quantum optical wavelength conversion for application ranging from wavelength-multiplexed quantum networks to frequency bin entanglement.
We have studied single photon level frequency up-conversion, and developed efficient single photon detectors and a highly sensitive spectrometer at a telecommunication wavelength (around 1310 nm). We have applied the detector and spectrometer to the implementation of a quantum key distribution system; to the characterization of an entangled photon source and a single photon source from quantum dots; to increase the temporal resolution of the single photon detector; and to study on high-order temporal correlation following frequency conversion. In this paper, we will present an overview on the frequency up-conversion technique and its applications in quantum information systems.
We developed low-noise up-conversion single photon detectors for 1310 nm based on a periodically-poled LiNbO3 (PPLN) waveguide. The low-noise feature is achieved by using a pulsed optical pump at a wavelength longer than the signal wavelength. The detectors were used in a quantum key distribution (QKD) systems based on polarization encoding, measurement for entangled photon pairs and spectrum measurement at single photon levels. In this paper, the overall detection efficiency and noise level of the detectors are characterized and the polarization and wavelength sensitivity of the detection efficiency is analyzed. The applications of this detector in quantum information systems are also described.