Dr Mike Tarbutt

Prof Ed Hinds

A microwave trap for sympathetic cooling of polar molecules

Cooling molecules into the microKelvin regime would give us a host of new applications. It would allow us to construct 'molecular clocks', and measure time more precisely (which, practically, means even better sat-navs). It would also enable us to measure fundamental constants - such as the 'roundness' of an electron - which would help to elucidate theories in particle physics and cosmology. These ultracold molecules also hold a lot of promise for quantum computation and quantum simulations, allowing us to better understand systems we could not hope to simulate on a classical computer.

 My project aims at cooling molecules into the microKelvin regime using 'sympathetic cooling'. We are constructing a microwave trap, which consists of two curved mirrors facing eachother to form a cavity. By injecting microwaves through a hole in one mirror, we can create an enormous electric field maximum in the centre, which creates a trapping force due to the electric field induced energy shifts (Stark shifts) on the rotational states of the molecules. Using polar molecules (which consist of two different atoms and form a molecule analogous to an 'electric bar magnet'), this trapping force is large enough to hold the molecules stationary.

 Once this side of the project is ready, the molecule trap will be integrated with an experiment where atoms are cooled using lasers. These very cold molecules (at microKelvin temperatures) collide with molecules (at a few hundred milliKelvin) in the microwave trap and cool them down.

 The project is only in the beginning stages, and I don't doubt that the nature of the trap will evolve and change over the course of the project, but my hope is that by the end of it, we will be able to trap molecules and have begun sympathetically cooling them.