Novel protocol for Quantum Key Distribution

The proposed effort develops the understanding required to assess the utility of using OAM states and quantum entanglement as a novel protocol for quantum key distribution for propagation through an aberrating medium such as the atmosphere. In addition a conceptual design of an experiment that is appropriate to further the development of this capability will be developed on the proposed Phase I effort with the intent that it will form the basis of the subsequent Phase II effort. In this regard significant progress has been made. A protocol has been developed using minimum energy loss vortex fields that is capable of increasing the BB84 bandwidth by almost a factor of two over very long propagation paths (on the order of a megameter) with moderate sized optics. BENEFIT: This work will significantly advance the state-of-art in secure laser communication by using entangled OAM states. Analysis results presented in this proposal do not include the impact of entanglement yet but illustrate that the bandwidth of the communication channel can be almost doubled compared to that obtained with the BB84 protocol when smaller optics are used. For similar sized optics the new protocol provides more than a factor of three larger bandwidth. Given this level of performance both commercial and military optical communication links should benefit greatly. In particular this work ensures that ground-to-space or space-to-ground links will be a reality.