The 2007 Lectures in Physics: Bose-Einstein Condensation
What is Bose-Einstein Condensation?
Bose-Einstein condensation is quite possibly one of the most beautiful paradigms of the "strangeness" of quantum mechanics: millions of atoms loose their individual identities and start behaving like a single wave. At room temperature each molecule in a room has its own identity defined by its position and velocity. However, as we decrease the temperature this velocity becomes smaller and smaller. The uncertainty principle then tells us, that a better knowledge of the velocity implies greater uncertainty in the position. Since we know that the velocity of the atoms decreases with decreasing temperature, our knowledge of the velocity increases (that is we know that it is closer to zero). Therefore, the position of the atoms becomes ever more fuzzy and the individual atoms occupy an ever-larger space. If these atoms are bosons they then start to overlap. At this temperature quantum statistics forces more and more atoms into a single quantum state - the Bose-Einstein Condensate.
This strange behavior had been predicted by Albert Einstein already in 1924/25  on the basis of Satyendranath Bose's work on photon statistics. Einstein had thought it impossible for experimentalist to ever be able to reach such low temperatures and indeed, it took 70 year for experimentalist to be able to demonstrate this for the first time. In 1995 the groups of Wolfgang Ketterle at MIT in Cambrige and of Wieman and Cornell in Boulder, Colorado used lasers and magnets to cool less than half a million atoms to the lowest temperatures that ever existed anywhere in the universe - and saw for the first time what we know today as a Bose-Einstein Condensate. This was rewarded with the 2001 Nobel Price.
Why Bose-Einstein Condensation?
Bose-Einstein Condensation in dilute vapors is a hugely interesting phenomenon in itself: The great control over all experimental parameters allows a very close comparison with and thus a stringent test of the theoretical predictions. Soon after its first demonstration it became clear that BECs are ideal research tools to examine a wide range of problems such as the Mott Insulator transition, non-linear Josephson oscillations, superfluidity, vortices and solitons. They are now even starting to be used to create the most sensitive accelerometers.
Prof., Massachusetts Institute of Technology
Nobel Prize (2001) in Physics
Prof., Head of Atom Optics Group, Laboratoire Charles Fabry,
Institut d'Optique, University of Paris (Sud)
Prof., Head of the Quantum Degenerate Gases Group, European Laboratory
for non-Linear Spectroscopy LENS), University of Florence
Wolf von Klitzing
Researcher, Group Leader,
Institute of Electronic Structure and Laser, FORTH
Royal Society Research Fellow, Atomic and Laser Physics,
Clarendon Laboratory, University of Oxford
Prof., Head of the 5th Institute of Physics,
University of Stuttgart
Research Director at C.N.R.S, Laboratoire Kastler Brossel,
Ecole Normale Superieure
Prof., Director of the CNR-INFM Research and Development Center on
Bose-Einstein Condensation, University of Trento