Fiber nonlinearity based entangled-photon sources

Entangled photons have special properties arising from their quantum nature and have been used for scientific purposes such as demonstrating quantum teleportation. Several fascinating applications for entangled photons have been proposed including quantum metrology, computation, communication, and key generation. However, generating entangled light is currently an experiment in itself, thereby hampering development of these promising applications. Most entangled light generation schemes use nonlinear crystals. Recently researchers associated with NuCrypt have pioneered entangled photon sources that exploit the nonlinearity inherent in standard optical fiber. This is beneficial in many regards including excellent modal purity and easy low-loss fiber interconnects. In this STTR we plan to leverage such designs to build a flexible entangled photon source. Our source will generate photons in the 1310nm spectral window allowing them to co-propagate with traditional 1550nm optical communication signals without deleterious cross-talk. We will investigate various fiber types and configurations in an effort to reduce the harmful Raman scattering, leading to increased entanglement quality or eliminating the need for fiber cooling. We will also investigate frequency conversion directly in the fiber to allow for high quality single-photon detection via Silicon detectors, which are much better than other types of detectors available for 1310/1550nm photon counting.