# Theoretical characterisation of systems for the development of atomic clocks

Atomic clocks are the most precise instruments ever constructed.

They work by locking the frequency of radiation source (e.g., a laser) to the resonance of an atomic transition.

As well as the canonical application of clocks (positioning, navigation, and timing), their unparalleled stability makes them exceptional tools for fundamental physics studies as well.

Atomic clocks may be used to:

- test quantum mechanics with extraordinary precision

- probe for evidence of exotic physics, such as violations of the equivalence principle

- search for or constrain possible variations of the fundamental constants

- search for dark matter and dark energy

It is currently an exciting time for atomic clocks, with the best optical atomic clocks approaching a staggering precision of parts in 10^20!

There are many proposals to develop new optical atomic clocks in alkali atoms (Rb, Cs) and alkali-like ions (Sr+, Ba+, Ra+).

In order to develop the most accurate atomic clocks, a thorough theoretical understanding of the atomic properties is required.

This may be achieved by calculating the atomic wavefunctions using highly-precise atomic structure methods, which will be used and developed in this project.

Quantities that must be calculated include atomic spectra, lifetimes of excited states, atomic polarisabilities, transition rates, light shifts (the perturbation of atomic levels by the lasers required for the clock operation), black-body radiation shifts, and many others.

Sensitivity coefficients, which determine how sensitive a particular clock transition is to variations in the fine-structure constants, will also be calculated.