title: Quantum secured gigabit optical access networks.
abstract: Optical access networks connect multiple endpoints to a common network node via shared fibre infrastructure. They will play a vital role to scale up the number of users in quantum key distribution (QKD) networks. However, the presence of power splitters in the commonly used passive network architecture makes successful transmission of weak quantum signals challenging. This is especially true if QKD and data signals are multiplexed in the passive network. The splitter introduces an imbalance between quantum signal and Raman noise, which can prevent the recovery of the quantum signal completely. Here we introduce a method to overcome this limitation and demonstrate coexistence of multi-user QKD and full power data traffic from a gigabit passive optical network (GPON) for the first time. The dual feeder implementation is compatible with standard GPON architectures and can support up to 128 users, highlighting that quantum protected GPON networks could be commonplace in the future.
authors.affiliation: Toshiba Research Europe Ltd, 208 Cambridge Science Park, Cambridge CB4 0GZ, UK.
authors.forename: Bernd
authors.initials: B
authors.lastname: Fröhlich
authors.affiliation: Toshiba Research Europe Ltd, 208 Cambridge Science Park, Cambridge CB4 0GZ, UK.
authors.forename: James F
authors.initials: JF
authors.lastname: Dynes
authors.affiliation: Toshiba Research Europe Ltd, 208 Cambridge Science Park, Cambridge CB4 0GZ, UK.
authors.forename: Marco
authors.initials: M
authors.lastname: Lucamarini
authors.affiliation: Toshiba Research Europe Ltd, 208 Cambridge Science Park, Cambridge CB4 0GZ, UK.
authors.forename: Andrew W
authors.initials: AW
authors.lastname: Sharpe
authors.affiliation: Toshiba Research Europe Ltd, 208 Cambridge Science Park, Cambridge CB4 0GZ, UK.
authors.forename: Simon W-B
authors.initials: SW
authors.lastname: Tam
authors.affiliation: Toshiba Research Europe Ltd, 208 Cambridge Science Park, Cambridge CB4 0GZ, UK.
authors.forename: Zhiliang
authors.initials: Z
authors.lastname: Yuan
authors.affiliation: Toshiba Research Europe Ltd, 208 Cambridge Science Park, Cambridge CB4 0GZ, UK.
authors.forename: Andrew J
authors.initials: AJ
authors.lastname: Shields