Optical clock for long holdover and fundamental physics

I am contributing to the Possible project. Our aim is to construct an optical
atomic clock using Strontium (Sr-87) that is both transportable and has world-leading frequency
stabilities of order 10-18. My personal contributions are to design the vacuum, electronics,
and external support systems, and to assist in the construction of the clock.
Atomic clocks are a technology that has existed for a few decades, although the stabilities
at which they operate has rapidly developed. Atomic clocks using Caesium (Cs) are currently
used to dene the SI second with frequency instabilities of order 10-15, we believe that in the
near future these will be replaced with more precise Sr alternatives.
There exist a number of motivations for developing such precise tools for metrology, these
include interests by external industry and for scientic purposes. In extreme environments,
such as when deeply submerged, satellite navigation and timing becomes unrealistic. In
these scenarios, atomic clocks may be used with poly-static radar to permit navigation and
surveillance. Alternatively, Pulsar-Timing-Arrays (PTAs) can be used to measure the passing
of gravitational waves via the ne timing variation in the received radio-waves from Pulsars.
Additional precision to the measurements of the timing of incoming radio bursts permits
sensitivities to smaller amplitude gravitational waves. Having a system that is not limited to
operation inside a laboratory, as is the case for the majority of operational atomic clocks, is
necessary in these deployed environments. The Possible project aims to combine all of these
requirements into an evolved version of a Sr optical clock that is transportable, compact, and
robust.