Low cost, short range free space quantum cryptography for consumer applications : pocket size for pocket change

David Lowndes, Stefan Frick, Nock, Richard W R +2 more

Lowndes, David, Godfrey, Mark S, Lynch, Alastair M +1 more

J. L. Duligall, M. S. Godfrey, K. A. Harrison +2 more

We present the design of a novel free-space quantum cryptography system, complete with purpose-built software, that can operate in daylight conditions. The transmitter and receiver modules are built using inexpensive off-the-shelf components. Both modules are compact allowing the generation of renewed shared secrets on demand over a short range of a few metres. An analysis of the software is shown as well as results of error rates and therefore shared secret yields at varying background light levels. As the system is designed to eventually work in short-range consumer applications, we also present a use scenario where the consumer can regularly 'top up' a store of secrets for use in a variety of one-time-pad (OTP) and authentication protocols.

Richard Hughes, W. T. Buttler, Paul G. Kwiat +6 more

David L D Lowndes

A Quantum Key Distribution system has been demonstrated with a focus on applicability of the technology to a consumer use model.The optical devices were split into a large, expensive "Quantum ATM" (the Bob terminal) and a small, cheap handheld section (the Alice device).Work was initially done to integrate the devices into a realistic demonstration system which was exhibited at several international conferences.Following this success, the devices constituent parts were isolated and improved upon.Work on the Alice device focused upon proposing a new scheme for light collimation and then investigating a method to enact this.In the Bob device the progress was directed towards a more effective single photon detection system utilizing active quenching.An asymptotic secure key rate of 20kb/s was obtained at a bit error rate (BER) of 4% corresponding to a daylight operation scenario.A docking scheme was enacted to simplify the alignment of the optical channel which was shown to be repeatable over at least 50 cycles.The system was also shown to be stable over an extended period of time.

J. L. Duligall, M. S. Godfrey, A. M. Lynch +3 more

We present the design and development of a novel free-space quantum cryptography system complete with purpose-built software that can operate in daylight conditions. Current commercial quantum cryptography systems are expensive, use purpose-built components and are made-to-order.