Controllable Persistent Atom Current of Bose-Einstein Condensates in an Optical Lattice Ring

In this paper the macroscopic quantum state ofBose-Einstein condensates in optical lattices is studied by solving theperiodic Gross-Pitaevskii equation in one-dimensional geometry. It is shownthat an exact solution seen to be a travelling wave of excited macroscopicquantum states resultes in a persistent atom current, which can be controlledby adjusting of the barrier height of the optical periodic potential. Acritical condition to generate the travelling wave is demonstrated and wemoreover propose a practical experiment to realize the persistent atomcurrent in a toroidal atom waveguide.