CDT Student Paper on Photon Detection published in Electronic Letters in joint research with Toshiba Europe Labs into Quantum Key Distribution

A paper produced jointly by a Centre PhD student based at Cambridge together with colleagues from Cambridge University Engineering Department and Toshiba Europe Laboratories has appeared in the influential journal 'Electronic Letters'.

Ketaki Patel, a PhD student based in Cambridge's Engineering department is a co-author of a paper titled 'Gigacount/second photon detection with InGaAs avalanche photodiodes' produced jointly with Cambridge colleagues and Toshiba Europe Laboratories. Toshiba Europe Laboratories have a collaboration with a number of the Centre's researchers, based at the University of Cambridge. Ketaki presented her research at the recent CDT Industry Day event at UCL on 20th January in front of an audience of industry representatives.

High count rate single photon detection at telecom wavelengths has been demonstrated using a thermoelectrically-cooled semiconductor diode. Ketaki helped to build a device consisting of a single InGaAs avalanche photodiode driven by a 2 GHz gating frequency signal and coupled to a tunable self-differencing circuit for enhanced detection sensitivity. The count rate is linear with the photon flux in the single photon detection regime over approximately four orders of magnitude, and saturates at 1 gigacount/s at high photon fluxes - the highest count rate among any single photon detectors. This result highlights promising potential for Avalanche Photodiodes (APDs) in high-bit-rate quantum information applications.

To read Ketaki's paper, please click here. To see Ketaki's recent presentation at the Centre's Industry Day, please click here.

Dr Zhiliang Yuan from the Quantum Information Group at Toshiba Research Europe Ltd said “We are developing quantum key distribution (QKD) to protect future communication networks. This technology is advantageous because its security is guaranteed by quantum mechanics. However, it also poses technical challenges, one of which is high-performance single photon detectors. So far, our self-differencing APDs have allowed the QKD secure key rate to break the 1 Mbit/s barrier for the first time. As a practical device they have withstood rigorous tests in the field environment in the 2010 Tokyo QKD network.”