Christopher Chunnilall, National Physical Laboratory, United Kingdom
National Physical Laboratory (NPL) is developing a measurement infrastructure for traceably characterising the quantum optical components of Quantum Key Distribution (QKD) systems, one of the most commercially advanced quantum technologies, and among the first to directly harness the peculiar laws of quantum physics.
These developments enable NPL to traceably characterise the single photon transmitter (‘Alice’) and receiver (‘Bob’) modules of weak-laser-pulse prepare-and-measure QKD systems operating at clock rates up to 1 gigahertz (GHz) over optical fibre in the 1550 nanometer (nm) telecom band. The measurement instrumentation can be synchronized with low jitter (< 10 picosecond root meter square) to the pulse emission or detector gate. The properties measured range from ‘traditional’ ones such as mean photon number(s), temporal bandwidth, jitter and detection efficiency, to others such as any distinguishing information that may have been imparted onto the photons (e.g. spectral information) which an eavesdropper can utilise.
I will describe the facilities that have been developed for traceably characterising the quantum optical components of QKD systems, and I will report on how one of these measurements was applied in real time to QKD-enabled data encryption over a single field-installed fibre.
If time permits, I may also give a brief overview of a recently-completed European collaborative project which aimed to develop metrology to underpin standards for fibre QKD.
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