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from them, thereby effectively reducing the atoms' energy causing them to slow down and cool. The second stage involves confining the already cool atoms in a strong magnetic field configuration analogous to a deep bowl which allows the cooled atoms to collect in a bunch at the bottom and the more active atoms to "evaporate" away from the top. Temperatures to within a few billionths of a degree Kelvin have been obtained this way without the use of cryogenic technology.

Studying and analyzing BEC's has become a popular pastime among physics researchers. Since the first BEC was created at the University of Colorado in 1995 twenty groups around the world were able to produce BEC's before the turn of this century. An example of how the condensate takes on the properties of a super atom involves the experiment at MIT wherein a cigar-shaped BEC cloud is induced into quadruple oscillation by modulating the magnetic containment field, causing the cloud to oscillate by contracting along the long direction and expanding along the short direction and vice versa. The fundamental frequency of this oscillation can be predicted based on the parameters of the cloud. Agglomerations of atoms in a BEC cloud about the size of a dime have been achieved.

Interestingly, a complete analogy to the behavior of photon wavelengths in lasers stops when separate clouds of BEC's interact. It is possible to cross two laser beams without disturbing either beam through their interaction. However, a condensate will offer some resistance to interference from another condensate, acting more like a fluid. On the other hand, Wolfgang Ketterle's group at MIT has observed a fringing pattern of alternating constructive and destructive wave interference when the waves of two condensates overlap, as occurs when two laser beams cross.

An example of Einstein's reference to "spooky behavior at a distance" was observed by Harvard researchers when they successfully halted a pulse of laser light in a BEC cloud of sodium atoms and then revived it in a separate BEC cloud a fraction of a millimeter away. This experiment is described in a February 7, 2007 article in Scientific American on-line.

Experiments on BEC's have for the most part involved the use of isotopes like rubidium-87 which naturally repel one another. They more readily produce BEC's. In one experiment of note the researchers at JILA altered the naturally attractive forces of rubidium-85 by using a magnetic field sweep to cause spin-flip collisions thereby inducing the Rb-85 atoms to repel one another. They were then able to form those atoms into a stable condensate. When the magnetic field strength was increased still further, the atoms reverted to attraction and the BEC cloud imploded and shrank beyond detection, then spontaneously exploded, releasing about two-thirds of its atoms. About half the atoms that made up the original BEC could not be located either in the remaining condensate or the expanding cloud of gas. Their strange disappearance has not as yet been satisfactorily explained and was not predicted by quantum theory although the physics community is not for want of ideas on the subject.

One might regard the study of Bose-Einstein Condensates to represent the cutting edge of research in the area of quantum physics. Observation of their behavior has for the most part corroborated all the theoretical and proposed quantum principles and speculation to date and further research on BEC's will most certainly aid in our understanding of the fundamental nature of reality.

Learn more about this author, Steve Lussing.
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