Multi-photon 3-Stage QKD for Practical Quantum Networks

Abstract

Abstract Quantum key distribution (QKD) will most likely be an integral part of any practical quantum network setup in the future. However, not all QKD protocols can be used in today's networks because of the lack of single photon emitters and noisy intermediate quantum hardware. Attenuated photon transmission typically used to simulate single photon emitters severely limits the achievable transmission distances and the integration of QKD into existing classical networks that use tens of thousands of photons per bit of transmission. Furthermore, it has been found that different protocols perform differently in different network topologies. In order to remove the reliance of QKD on single photon emitters and increase transmission distances, it is worthwhile exploring QKD protocols that do not rely on single-photon transmissions for security, such as the 3-stage QKD protocol; the 3-stage protocol can tolerate multiple photons in each burst without leakage of information. This paper compares and contrasts the 3-stage QKD protocol and its efficiency in different network topologies and conditions. Further, we establish a mathematical relationship between achievable key rates for increasing transmission distances in various topologies. Our results provide insight to a network engineer in designing QKD networks of the future.