|
A Bose-Einstein condensate trapped in a two-dimensional optical lattice
exhibits an abrupt transition manifested by the macroscopic wavefunction
changing character from spatially localized to extended. This transition
takes place as the interwell potential barrier is adiabatically decreased
below a critical value and is irreversible, since increasing the interwell
barrier back to its initial value does not restore localization.
This is in sharp contrast with the corresponding one-dimensional case where a similar delocalization is continuous and reversible. The different behavior reflects the existence of a critical point (bifurcation) for the appearance of localized stationary states in two dimensions. References: [1] Phys. Rev. Lett. 89, 030402 (2002) Collaborators: K.O. Rasmussen and A.R. Bishop, Los Alamos National Lab. |