On the 24th June 2003 we created the first Bose-Einstein condensate (BEC) in Scotland at Strathclyde, joining the many groups worldwide that can now produce BECs. Our condensate contains about 5 105 87Rb atoms in the |F=2,mF=2> state. The BEC was created at a localised position at the top of our storage ring, and we have now sent the condensate around the ring. We can also split the condensate into two halves which rotate in opposite directions around the ring.

Absorption images of the BEC after expansion, illustrating the atomic velocity distribution. As the temperature drops a very cold distribution appears - a Bose-Einstein condensate.

Introduction: The concept of atoms as particles is familiar to many, however at the microscopic level the classical laws of physics break down, and the wave nature of matter becomes apparent - this is the realm of quantum mechanics. If one makes an atomic vapour of bosons cold and dense enough that the inter-atomic spacing approaches the thermal de Broglie wavelength, then a phase transition occurs and all of the atoms coalesce into the same (lowest energy) quantum state. Such a Bose-Einstein condensate (BEC), in which all of the atoms behave in essentially the same way, is thus the atomic analogue of a laser - an atom laser. These atom lasers are coherent macroscopic quantum objects large enough to be observed on a simple CCD camera - bringing textbook quantum mechanics to life. The concept of a BEC, once regarded as a curiosity, sparked an extremely active new research area in the forefront of physics following its startling experimental realisation with cold atomic vapours in 1995. Achievements in the field to date ensured the 2001 Nobel Physics Prize for those who first experimentally realised BEC.

BEC at Strathclyde: We are grateful to the EPSRC for providing experimental funding for the BEC experiment (2000-2003). We used the three-step route to BEC that has been most commonly used to date: laser cooling, followed by magnetic trapping and evaporative cooling. The main difference with our experiment is that our ⁸⁷Rb condensate is confined in a large toroidal storage ring. This novel geometry should enable extremely sensitive atom interferometry.

BEC Lab Images: 1 Our home-made 780nm, 50mW output, 1MHz pp linewidth diode lasers. 2 The optical table. 3 The low pressure (3 10-11torr, 40s magnetic trap lifetime) end of our 109 87Rb atom double magneto-optical trap (MOT). 4 Closeup of the 'low' pressure MOT. Five water-cooled MOSFET banks control the 500A magnetic coils, which can be used in three configurations: MOT, Ioffe-Pritchard magnetic trap, toroidal magnetic trap.

Further Info: A great source of information about all things BEC-related is the UltraCold Atom News (UCAN) page. If you're interested in working on the 'giant' toroidal BEC experiment (or if you're just plain curious) please contact us.... a PhD position is available.

The BEC team:

Aidan Arnold Erling Riis Paul Griffin Mateusz Zawadzki