title: No-switching quantum key distribution using broadband modulated coherent light.
abstract: We realize an end-to-end no-switching quantum key distribution protocol using continuous-wave coherent light. We encode weak broadband Gaussian modulations onto the amplitude and phase quadratures of light beams. Our no-switching protocol achieves high secret key rate via a post-selection protocol that utilizes both quadrature information simultaneously. We establish a secret key rate of 25 Mbits/s for a lossless channel and 1 kbit/s for 90% channel loss, per 17 MHz of detected bandwidth, assuming individual Gaussian eavesdropping attacks. Since our scheme is truly broadband, it can potentially deliver orders of magnitude higher key rates by extending the encoding bandwidth with higher-end telecommunication technology.
authors.affiliation: Quantum Optics Group, Department of Physics, Faculty of Science, Australian National University, ACT 0200, Australia.
authors.forename: Andrew M
authors.initials: AM
authors.lastname: Lance
authors.forename: Thomas
authors.initials: T
authors.lastname: Symul
authors.forename: Vikram
authors.initials: V
authors.lastname: Sharma
authors.forename: Christian
authors.initials: C
authors.lastname: Weedbrook
authors.forename: Timothy C
authors.initials: TC
authors.lastname: Ralph
authors.forename: Ping Koy
authors.initials: PK
authors.lastname: Lam