When the depths of space are not cold enough

May 2006.

R. Dall (left) and A. Truscott

In 1925, based on work by Satyendra Nath Bose, Albert Einstein proposed that if one could make a collection of atoms cold enough, they would condense into a single quantum state making each atom identical to its neighbours in a similar way to photons in a laser beam. It wasn’t until seventy years later that scientists were able to actually create the world’s first Bose Einstein-Condensate (BEC) in the laboratory.

BECs are interesting because they represent an entirely new state of matter not found naturally anywhere in the universe. Even the coldest depths of space are a billion times too hot for a BEC to exist because of residual radiation from the big bang. BECs have strange quantum properties that may yield useful future technologies. However, in order unlock this potential, scientists need to better understand BECs and especially their process of formation. Studying the formation process in conventional ground state alkali atom BECs is complicated by the inability to detect individual constituent atoms. Measurements on such systems are limited to averaging over the quantum ensemble.

To get around this, scientists at the ANU have recently become one of only four groups in the world to achieve a BEC of metastable helium atoms. This particular atomic configuration of helium has vastly more energy than the ground state and is sufficiently long lived to allow experiments to be performed on it. What’s special about this BEC is that because of the great internal energy of the excited atoms, they are able to release an electron when they contact a metal probe. This means they can be detected individually. Since atoms in a BEC cloud are all quantum identical, probing one yields a perfect snapshot of the others and individual quantum effects become visible in much greater detail. The ANU team is hopeful that this newly functioning BEC apparatus will yield vital clues to the mechanism of BEC formation.

The history of physics is full of examples of strange and exotic phenomena that having been developed out of pure curiosity, have gone on to spawn unimaginable technological advances. Lasers, X-rays, and transistors all belong to this family and BECs may well be its newest member.

The paper reporting the creation of a BEC of metastable helium atoms at the ANU is due to published in the October 2006 issue of Optics Communications; see: Optics Communications (2006).

Media:
For further information, contact:

Ms Ruth Wilson
(Cheif Operations Manager of ACQAO)
ruth.wilsonanu.edu.au
(+61-2) 6125 4203

and

Dr Andrew Truscott
andrew.truscottanu.edu.au
(+61-2) 6125 4203