Below a certain critical temperature, which is close to absolute zero (0 K, −273.15 °C, or −459.67 °F), systems of trapped bosonic atoms become Bose-Einstein condensed superfluids. In this systems, a macroscopic fraction of the particles occupies the lowest-energy "wave" in the box in which the atoms are kept, so that quantum effects become apparent on a macroscopic scale. The first step in almost any ultracold gas experiment consists in cooling a gas of atoms to "degeneracy." This means that it is so cold that the de Broglie wave of one atom starts to overlap with that of its nearest neighbor. When the atoms in question are bosons, the result is a Bose-Einstein condensate (BEC). In 1995 the first BEC of bosonic alkali atoms were produced, which is a new state of matter recognized by the Nobel Prize in Physics 2001. BECs are by now routinely studied worldwide in systems of millions or more atoms, down to temperatures some billionths of a degree above absolute zero.
The CMP researchers at the University of Delaware are involved in theoretical and computational modeling of BEC condensates in ultracold trapped gases of bosons or boson-fermion mixture and superfluid Helium.
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A. R. Sakhel, J. L. DuBois, and H. R. Glyde, Condensate depletion in two-species Bose gases: A variational quantum Monte Carlo study, Phys. Rev. A 77, 043627 (2008). [PDF]
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