Bragg Spectroscopy of a Strongly Interacting Fermi Gas 

Posted: Friday, 13 Feb 2009

ACQAO researchers Gopi Veeravalli, Eva Kuhnle, Paul Dyke and Chris Vale at Swinburne University of Technology’s Centre for Atom Optics and Ultrafast Spectroscopy (CAOUS) have recently performed the first study of pairing in ultra cold Fermi gases using Bragg spectroscopy.  This work may help elucidate the nature of pairs that form fermionic superfluids.  Such superfluids display remarkable properties such as flow without resistance, or in the case of superconductors, the flow of current without any loss of power.

Ultracold Fermi gases offer a pristine and highly controllable resource to probe the behaviour of fermionic quantum systems.  This research utilised a gas of fermionic ⁶Li atoms cooled well below one millionth of a degree above absolute zero.  The Cold Molecules lab at Swinburne is the only lab in the southern hemisphere capable of producing such ultracold fermionic systems.

The Swinburne team, have shown how the technique of Bragg spectroscopy can be used as a new probe of the pair correlations in these strongly interacting quantum systems.  At low temperatures, these pairs can undergo Bose-Einstein condensation which leads to superfluidity.  The team are now investigating the way pair correlations build up as the atoms are cooled to lower and lower temperatures.

This research has been published in Physical Review Letters - Phys. Rev. Lett. 101, 250403 (2008)