Rydberg atoms are atoms with a large principle quantum number. One possibility to create them is to excite ground state atoms with lasers. They are very sensitive to electric fields, so if you bring them close together they will experience very strong interactions due to static or induced electric dipoles.
We have now put a paper onto the arXiv, where we investigate the properties of the strongly interacting regime. We have found some interesting links between Rydberg physics and concepts originally coming from condensed matter physics.
For the strongly interacting regime we have shown that exciting Rydberg atoms with lasers results in quantum critical behavior. In a nutshell, this means that physical quantities behave independent of the microscopic details, no matter whether the atoms form a thermal gas, a Bose-Einstein condensate or sit on a lattice. The reason for this is that such a driven Rydberg system is close to a second order quantum phase transition, where critical behavior can be expected. Nevertheless the underlying physics are quite simple: all you need to do is to shine with lasers on atoms.
Reference: H. Weimer, R. Löw, T. Pfau, H. P. Büchler.
Quantum critical behavior in strongly interacting Rydberg
gases Phys. Rev. Lett. 101, 250601
Copyright 2006--2011 Hendrik Weimer. This document is available under the terms of the GNU Free Documentation License. See the licensing terms for further details.