A Novel QKD Protocol Utilizing Temporal Correlations in Photon Pairs

We introduce a novel QKD protocol which utilizes the intrinsic temporal correlations found in photon pairs from a two-mode squeezed vacuum (TMSV) state. Upon generation, the idler photons are measured right away by Alice, and their time stamps recorded. This idler detection heralds the corresponding signal photons traveling in the channel towards Bob, which ensures the temporal configuration of the photons is identical between the two sets of photons when Bob measures them as a later time. By converting the time intervals between these photons into an uniformly-distributed integer stream, we generate two matching streams of integers which can be used to generate a secure key. The security of this key-generation scheme is discussed and investigated, as well as the utilization of this system in a real-world environment. The introduction of dropped photons and dark counts requires the use of non-standard error correcting codes. We discuss the use of Marker codes in the system and how correction and privacy amplification can occur without allowing knowledge of the full key to transmit to an eavesdropper.