Manipulating photon coherence to enhance the security of distributed phase reference quantum key distribution

George L. Roberts, Marco Lucamarini, James F. Dynes, Seb J. Savory, Zhiliang Yuan, Andrew J. Shields
2017 Applied Physics Letters  
Quantum key distribution (QKD) allows two users to communicate with theoretically provable secrecy by encoding information on photonic qubits. Current encoders are complex, however, which reduces their appeal for practical use and introduces potential vulnerabilities to quantum attacks. Distributed-phase-reference (DPR) systems were introduced as a simpler alternative, but have not yet been proven practically secure against all classes of attack. Here we demonstrate the first DPR QKD system
more » ... information-theoretic security. Using a novel light source, where the coherence between pulses can be controlled on a pulse-by-pulse basis, we implement a secure DPR system based on the differential quadrature phase shift protocol. The system is modulator-free, does not require active stabilization or a complex receiver, and also offers megabit per second key rates, almost three times higher than the standard Bennett-Brassard 1984 (BB84) protocol. This enhanced performance and security highlights the potential for DPR protocols to be adopted for real-world applications.
doi:10.1063/1.5004488 fatcat:4mrgyqxto5agpafvjcmv7pfn34