ARC-MAC: A robust condensed-matter miniature atomic clock

Precise and reliable timekeeping is essential to the infrastructure on which modern society depends. Mobile phone signals, financial markets, radio broadcasting, radar, and the electricity grid all need precise synchronisation (often with a precision of microseconds or better) between different elements of the network.

This synchronisation is presently achieved via signals from global navigation satellite systems (GNSS) such as the GPS network. However, these signals are vulnerable to space weather, to jamming, spoofing (false signal), and meaconing (delaying and rebroadcasting), or potentially even from satellites being shot down. This is a key strategic vulnerability for the UK, as recognised by a Blackett Review in 2018\. At the time, the main risks were accidental jamming and solar storms; however, since the invasion of Ukraine, deliberate jamming has become widespread both within and outside the war zone, with a clear risk that it could be deployed against the UK.

The way to mitigate this vulnerability is to equip GNSS-diciplined clocks with a holdover capability, by incorporating clocks that will keep them synchronised through a prolonged outage. These clocks must be extremely accurate (at the level of microseconds over a week), but also rugged and stable enough to be deployed across a wide range of applications, wherever there is a requirement for low size, weight, power, and cost.

The aim of this project is to develop a new type of atomic clock that will meet this need. The clock is based on endohedral fullerenes, which are molecules that have many of the advantages of trapped atoms but -- crucially -- avoid any need for vapours or optics. We have already demonstrated such a clock, working on a benchtop. During this project we will develop a smaller precommercial prototype and test it thoroughly across the full range of environmental conditions it will need to withstand. The result will be a new class of condensed-matter clock, ready to be integrated into GNSS devices and with potential for further miniaturisation, eventually into consumer electronics and the internet things.