Optical Clock Arrays for Quantum Metrology

Many aspects of the modern world are underpinned by precise timing and synchronisation, from financial trading and power grids, to satellite navigation. This precise timing is provided by atomic clocks which are currently based on microwave transitions in atoms like caesium. However, atomic clock research is currently undergoing a revolution, as clocks switch from microwave transitions to optical transitions, which has enabled the performance of state-of-the-art clocks to improve by a factor of over one hundred in just ten years.

Ultimately the performance of these clocks will be limited by statistics - the accuracy of measurements is determined by the number of independent trials (much like measuring the probability that a coin is fair by tossing it many times). In practice, the maximum number of atoms that can be used in such a clock is limited. However it has been known for over thirty years that this limit can be broken using a quantum property known as entanglement, where the atoms in the clock are correlated rather than independent.

The big challenge that we address in this proposal is to create the right kind of entanglement in an optical atomic clock for the first time. To do this we will build a new type of optical atomic clock where each atom can be controlled independently. To correlate the atoms, we will exploit state-of-the-art methods based on exciting the atoms to high-energy states known as Rydberg states.

The breakthrough that we target is the first proof-of-principle demonstration of an entanglement-enhanced measurements in an optical atomic clock.

This proposal addresses the challenge of creating squeezed states in an optical atomic clock. The primary impact will be on the time and frequency metrology community and the wider academic community exploring quantum metrology and quantum simulation. However, atomic clocks are a mature quantum technology that underpins a wide range of economic sectors. Within the UK National Quantum Technology Programme and elsewhere there are major efforts to develop optical atomic clocks for applications. Therefore there is potential for wider impact in the following ways:

Short term (2-5years)
Knowledge transfer: The project brings expertise from the quantum simulation community (addressable arrays of single atoms) into the domain of optical atomic clocks, impacting research and development underway in the Quantum technology community on robust optical clocks for applications.
Trained personnel: Two PDRAs will be trained in state-of-the-art methods at the interface of quantum simulators and clocks, providing a resource for the Quantum technology community.

Medium term (5-10 years)
On this timescale, the project opens a route to entanglement enhanced measurements in optical atomic clocks, with the potential to improve measurement precision or speed. This underpinning science will create impact through the provision of the next generation of quantum technologies for atomic clocks.

We also propose to develop our longstanding track record of high quality public engagement and outreach activities.