Experiments in Dilute Atomic Bose-Einstein Condensation
Eric A. Cornell, J R. Ensher, C E. Wieman
Why BEC? - In the month we began writing this paper, fourteen papers on the explicit topic of Bose-Einstein condensation (BEC) in a dilute gas appeared in the pages of Physical Review. Both theoretical and experimental activity in BEC has expanded dramatically in the three years since the first observation of BEC in a dilute atomic gas. One is tempted to ask, why? Why is there so much interest in the field? Is this burst of activity something that could have been foreseen, in say, 1990? We feel the answer to this last question is yes: while interesting is a quality which is impossible to define, there was good reason to anticipate, even in 1990, that dilute-gas BEC was going to be something worth investigating. To see why, one need only perform the following simple test. Ask any physicist of your acquaintance to compile a list of what he or she considers the six most intriguing physical phenomena that occur at length scales greater than a picometer and smaller than a kilometer. In our experience, such lists almost always include at least two of the following three effects: superfluidity, lasing, and superconductivity. These three topics all share two common features: counterintuitive behavior and macroscopic occupation of a single quantum state. This then would have been our clue-one might have anticipated that dilute-gas BEC was to be interesting because it shares the same underlying mechanism with the widely appreciated topics of lasing, superfluidity, and superconductivity, and yet is quite different from any of them: Dilute-gas BEC is more amenable to microscopic analysis than superfluidity, more strongly self-interacting than laser beams, and it possesses a range of experimental observables which are complementary to those of superconductivity. This paper will not pretend to provide a through survey of the status of dilute-gas BEC experiment. Any attempt to do so at this time would surely be obsolete by the time it appears in print-such is the pace of developemnts these days. Rather, we will try to cover the same pedagogical ground as the set of lectures delivered by one of us (EAC) at the 1998 Enrico Fermi summer school on Bose-Einstein condensation. The lectures were coordinated with other experimenter-lectures at Varenna, and thus were not meant to be comprehensive. This paper as well will be selective in tis focus. An outline of this paper is as follows: We begin with an introductory section including a review of ideal-gas BEC theory . The second section presents a history of the subject, and the third a forward-looking summary of BEC technology. The fourth section introduces the important topic of interactions in the condensate and surveys experimental work on interactions. The fifth section discusses, mainly by reference to published articles, experiments on condensate excitations. The sixth section is a brief essay on the meaning of the phase of a condensate. The seventh section surveys what is known about heating processes in trapped atom samples, and examines the implications for trapping very large samples. The eigth section contains some general observations on atomic collisions relevant to evaporation.
Proceedings of the International School of Physics Enrico Fermi
July 7-17, 1998
Varenna on Lake Como, IT
International School of Physics Enrico Fermi
, Ensher, J.
and Wieman, C.
Experiments in Dilute Atomic Bose-Einstein Condensation, Proceedings of the International School of Physics Enrico Fermi, Varenna on Lake Como, IT
(Accessed December 6, 2023)