Project title: Optical frequency metrology with an ytterbium ion clock
Supervisors: Richard Thompson (Imperial College) and Rachel Godun (NPL)
Optical clocks are based on spectroscopy of transitions in the optical range, which allow for a considerable improvement in frequency stability compared with atomic clocks based on microwave transitions. With optical clocks already outperforming caesium primary standards by nearly two orders of magnitude, it is anticipated that the SI second will soon be redefined in terms of an optical frequency. The exceptional sensitivity of optical clocks can be exploited for fundamental physics tests, such as the variation of the fine structure constant, which can allow the detection of dark matter.
At the heart of this project lies the ytterbium (Yb) ion optical clock at the National Physical Laboratory (NPL). We are continuously trying to minimise the uncertainties on systematic frequency shifts due to perturbations on the ion. I will help develop a second almost identical ion trap and bring it into operation, and will then contribute to the optimisation of its frequency stability and accuracy. This will serve as an independent check of the clock’s performance; by the end of my project, I aim to achieve a level of uncertainty in the 10-18 range in both systems. Furthermore, I will be participating in international clock comparison campaigns that are regularly carried out to ensure that optical clocks developed in different institutions agree within their estimated uncertainties.