Cold-atom source of strontium for Quantum Technology

Accurate navigation on earth and in space relies on precise and accurate timekeeping. Better clocks will give faster data transfer, improved positioning, and new science applications. A significant and increasing fraction of the UK GDP depends on Global Navigation Satellite Systems (GNSS) technologies. Location based services associated with mobile broadband services are driving further growth. Thus ensuring the proper dissemination of time from the worldwide network of National Metrology Institutes (NMIs) is essential to the functioning of the economy and infrastructure of the UK, and other developed countries. Networked systems have vulnerabilities, however, and these risks need to be mitigated by having standalone oscillators distributed in the system that can continue providing the required service. The new generation of optical clocks provides a 100 times better performance and will enhance the capabilities of GNSS. As systems evolve to make use of this higher precision it is vital to improve the `holdover' technology in order to guarantee continuity. Atomic microwave clocks have been available commercially for many years and are at the heart of communication systems, e.g. a contributor to the synchronization of GPS is the ensemble of over 50 devices maintained at the US Naval Observatory.

Clocks use the internal energy levels of atoms to control the frequency of an oscillator accurately. Optical clocks that use lasers to interrogate atomic transitions are several orders of magnitude better than devices based on microwave transitions because the optical transitions have higher frequency and are chosen to have a higher 'quality factor'. Laser cooling of atoms has revolutionised timekeeping and this dramatic change is spreading to other quantum technologies for precision measurements such as matter-wave interferometers used as inertial sensors for navigation and gravimeters for surveying. There are also major research applications of atom interferometry in fundamental physics such as new types of detector for dark matter and gravitational waves. The experimental methods that are being developed to build atom interferometers with large baselines (kilometre scale) use the special properties of the extremely narrow clock transition in strontium atoms and adapt the technology that has been developed for optical clocks. This project seeks to develop a source of laser-cooled strontium atoms that is a key component in the supply chain for the fabrication of the next generation of such quantum devices.

This project will support the development of a high-flux cold-atom source of strontium to a Technology Readiness Level at which it can be supplied to others for integration into instruments. We will also test new aspects of atom sources such as pulsed operation to prolong the lifetime, which is an important consideration for the deployment of clocks and quantum instruments outside of research laboratories, for example in projects to build very large-scale interferometers in deep shafts where access is restricted.