In the last five years there has been a surge of theoretical and experimental work aimed at understanding the fundamental properties of Bose-Einstein condensates, the long term significance of which was recognised by the award of the 2001 Nobel prize in Physics [1]. This new state of matter forms at extremely low temperatures and was observed for the first time in a cloud of laser-cooled rubidium atoms. Recent work is partly motivated by expected applications in high precision measurements and quantum information technology. Click here for a BEC introduction.

Perhaps one of the most exciting developments has been the recent invention of the micro-BEC. Almost all current experiments trap neutral atomic clouds using a magnetic field created by a complicated arrangement of massive electromagnetic coils. However it has recently been demonstrated that a microscopic magnetic trap for BEC formation can be created just above a silicon substrate on which a simple network of current carrying wires is printed (similar to a computer chip and therefore known as an atom chip) [2]. This results in an experiment with different technical challenges but with a number of distinct advantages.

Our atom chip bracket with wires for trapping atoms	The atom chip in the glass cell under vacuum	Atoms trapped in a surface magneto-optical trap. The cloud of atoms are a few mm below the chip and are circled in red.

The atom chip allows much greater flexibility in designing experiments, as atom optical elements can be lithographically created or etched, using well understood fabrication technology, forming a quantum network for atoms. Atoms can be easily manipulated on the surface of a chip by changing currents in the micro-wires that are used for trapping [3]. This gives much greater control than conventional BEC experiments, which are limited to the use of laser light and large scale magnetic fields to manipulate their condensates. In addition, the creation of a BEC is favourable in the magnetic fields produced by the chip since a BEC will condense in a much shorter time than in a macroscopic trap.

Click here for more details on making a Micro-BEC

[1]1. M.H. Anderson, J.R. Ensher, M.R. Matthiews, C.E. Wieman and E.A. Cornell, Science 269,198 (1995); C.C. Bradley, C.A. Sackett, J.J. Tollett and R.G. Hulet, Phys. Rev. Lett. 75, 1687 (1995); K.B. Davis, M.O. Mewes, M.R. Andrews, N.J. van Druten, D.S. Durfee, D.M. Kurn and W. Ketterle, ibid. 75, 3969 (1995).

[2] H. Ott, J. Fortagh, G. Schlotterbeck, A. Grosmann, and C. Zimmermann, Bose-Einstein condensation on a Surface Microtrap, PRL 87, 230401-1, 2001; W. Hansel, P. Hommelhoff, T.W. Hansch, and J. Reichel, Bose-Einstein Condensation on a Microelectronic Chip, Nature 413:3, October, 498 (2001).

[3] W. Hänsel, J. Reichel, P. Hommelhoff, and T.W. Hänsch, Phys, Rev. Lett. 86, 608 (2001).