Klaus Mueller-Dethlefs (Manchester)
Event Date and Time:
Thu, 2012-01-19 17:30
Bose-Einstein Condensation (BEC) was first achieved in the liquid phase in helium a century and, for gas phase atoms, a decade ago. The question arises if there could be a third BEC of a solid, crystalline, state. A possible pathway towards such a new state of matter is a quantum plasma for which the de Broglie wavelength becomes larger than the mean distance between particles. For the electrons in an ultra-cold ion-electron plasma this condition is fulfilled for a temperature below 0.1K and a density above 1015 cm3. We produce such an ultra-cold Rydberg plasma by laser threshold ionization of NO molecules in the high-density expansion region of a supersonic jet close to the nozzle. This plasma has an extremely long lifetime of milliseconds and it shows the compressibility of a “sponge like” ultra-soft solid. An explanation is the formation of an electron Wigner crystal, which according to A A Abrikosov should also lead to the formation of a lattice of the cations. A possible cooling mechanism for the molecular cations (such as 14N16O+ Bosons) towards quantum degeneracy, i.e. a molecular Bose-Einstein Condensate will be discussed.