Correlations are one of the central features of modern condensed matter physics. They arise in systems where the behavior of any given particle in a system depends strongly on all the other particles. Such correlations are what help distinguish the relative simplicity of a gas (a largely uncorrelated system where the average atom's behavior doesn't depend much on the other atoms) from more complicated, and more interesting, condensed matter systems. Not surprisingly, correlated systems can be the hardest to understand theoretically, since we must know a lot about a large number of particles in order to understand any of the microscopic behavior. In traditional condensed matter materials, correlations are caused by two sources: interactions (e.g. electrons repel each other and avoid being in the same place) and quantum statistics, (e.g. Fermionic particles like electrons tend to "repel" each other due to the famous Pauli exclusion principle). In this issue, Syassen et al. show that another, somewhat counter-intuitive, approach is possible: collisional loss, where pairs of colliding particles disappear from the system, can lead to particle correlations. This approach uses unique properties of trapped dilute quantum gases to realize many-body physics, and may lead to fundamentally new ways to generate interesting correlated states with ultra-cold atoms.
Citation: Science Magazine
Pub Type: Journals
cold atoms, correlations, degenerate gases, optical lattice, tonks-girardeau