Funding for this research was provided by:
Engineering and Physical Sciences Research Council (EP/L015730/1, EP/M013472/1)
Received: 15 July 2019
Accepted: 22 April 2020
First Online: 1 May 2020
: While the work was being carried out and a first draft of this paper was written, the authors had no competing interests. Since then, CE has moved to become the CEO of a quantum security company, focusing on the commercialisation of integrated QKD hardware.