Repository logo

Practical, high-speed Gaussian coherent state continuous variable quantum key distribution with real-time parameter monitoring, optimised slicing, and post-processed key distillation

Published version

Repository DOI

Change log


Weerasinghe, Weerasinghe 
Alhussein, Muataz 
Alderton, adam 
Wonfor, Adrian 
Penty, Richard 


Gaussian coherent state continuous variable quantum key distribution has gained interest owing to its security and compatibility with classical coherent optical fibre networks. For successful system deployment it is necessary to implement practical high speed systems which distil keys efficiently. Here, we demonstrate a Gaussian coherent state continuous variable quantum key distribution system at a 50 MHz symbol rate. Unlike most demonstrations to date which measure excess noise and infer key rates from this, we record signals in real time and distil keys. We also demonstrate, for the first time, slice reconciliation with optimised guard bands to maximise achievable secret key rates. Using this optimisation with multilevel slicing, a record 5 Mb/s secret key rate after a transmission distance of 25 km is achieved. This is a significant improvement on the 3 Mb/s secret key rate which is achieved with single level optimised slice reconciliation.


Acknowledgements: This work has been funded by the UK EPSRC Quantum Communications Hub, project EP/T001011/1. The authors would like to acknowledge He Li for his contributions to secure key generation algorithms.


5108 Quantum Physics, 40 Engineering, 4009 Electronics, Sensors and Digital Hardware, 51 Physical Sciences, 5102 Atomic, Molecular and Optical Physics

Journal Title

Scientific Reports

Conference Name

Journal ISSN


Volume Title



Nature Portfolio
EPSRC (via University of York) (EP/T001011/1)
Is supplemented by: