Innovative and Robust Pulsed Entangled Photon Sources at 780 nm

Quantum communication through space-Earth and space-space quantum channels allows for the distribution of quantum information in the form of photonic qubits and can enable the creation of a global-scale quantum network. Such a network can link quantum computers and quantum sensors that can perform tasks, which have no classical counterpart. To support these capabilities, high-quality entangled-photon sources need to be developed. Within this program, Physical Sciences Inc. (PSI) and the University of Illinois Urbana-Champaign (UIUC) will continue to develop a low-Size, Weight, and Power (SWaP) pulsed entangled-photon source at wavelengths suitable for free-space and fiber-based communication. The proposed pulsed entangled-photon source relies on two reliable, low SWaP technologies. The first technology is a high repetition-rate Er-doped fiber laser that is frequency tripled and used as a pump source for spontaneous parametric down-conversion. The second technology is a source of polarization-entangled photons based on a non-linear crystal placed into a linear beam-displacement interferometer. Building on a successful Phase I effort, in Phase II we will develop, build, and test a fully-packaged, low SWaP second-generation entangled-photon source. This source will generate high brightness (200×103  photons/sec/mW), high fidelity (>97%), entangled-photon pairs with high heralding efficiency (>80%) for quantum-information applications.