Atomic System for Quantum Secure Communications

The future of secure ground-space and space-space communications relies on development of quantum secure communications (QSC) systems. ColdQuanta proposes to develop QSC devices based on compact, robust vacuum systems containing dense ensembles of cold, trapped rubidium atoms. In particular, we propose to develop a source of high-flux, high-coherence entangled photon pairs (biphotons). These biphotons can be used to transmit information in a provably secure manner that is consistent with existing QKD protocols and other real-time secure information transfer protocols. The proposed atomically sourced biphotons outperform photon pairs from existing solid-state sources by over a factor of 1000 in coherence time and spectral linewidth. The narrow spectral linewidth of the atomically sourced biphotons makes them compatible with direct interfacing with downstream atomic systems, opening vast new vistas in the potential for long-range QSC and quantum networking. A second direction that further pushes the state-of-the-art in highly-coherent quantum optical systems for QSC is our second proposed device that provides efficient storage and recall of single-photon states. The single photons are stored in a coherent collective excitation of a cold atomic ensemble and can later be retrieved when the downstream QSC system is ready. Together, these devices represent a dramatic step forward in the quality of commercially available QSC hardware components. Nevertheless, the parallel development of the devices will be highly efficient due to their shared reliance on identical underlying cold atom hardware. These devices (and potentially several other related quantum optical devices) will be different laser and optical packages wrapped around an identical vacuum system for production of atomic ensembles with extremely high optical density. Phase I will demonstrate the underlying atom ensemble hardware and will complete system-level designs of the proposed QSC hardware components.