Dr Mike Tarbutt

Dr Ben Sauer

Direct laser cooling of BH molecules

 Cold and ultracold states of matter can be used in the search for new physics, in addition to testing current theory at its extremes. Techniques for producing ultracold atomic sources are already well developed. Dipolar molecules have a more complicated structure than atoms which makes them more difficult to cool, but this also increases the range of potential applications. A source of ultracold, dipolar molecules might be used in precision measurement, simulating many-body systems and quantum information processing. The goal of my project is to produce and cool the molecule BH, which consists of one boron and one hydrogen atom. BH has been chosen for its energy-level structure, which should be amenable to direct laser cooling using just two laser frequencies; and its strong dipole moment, which would allow us to perform logical operations on the cooled system.

 We produce BH through photolysis of a diborane (B2H6) precursor and expand it from a region of high pressure into a vacuum chamber. This initial expansion results in molecules which have a high translational velocity but are cooled in their vibrational and rotational degrees of freedom. We can use Doppler laser cooling on a collimated beam extracted from this expansion to decelerate the molecules to the point at which they can be trapped in a magneto-optical trap. Once trapped we hope to be able cool the sample further, and eventually couple to a microwave field to exploit the unique properties of the system.


  • Molecular source brightness, MMQA junior meeting, Durham University, 2012


  • Direct laser cooling of the BH molecule, QuAMP, Swansea University, September 2013
  • Towards a bright source of ultracold BH molecules, QuICC, Aberystwyth University, September 2012