Band gaps for atoms in light-based waveguides

The energy spectrum for a system of atoms in a periodic potential can exhibit a gap in the band structure. We describe a system in which a laser is used to produce a mechanical potential for the atoms, and a standing-wave light field is used to shift the atomic levels using the Autler-Townes effect, which produces a periodic potential. The band structure for atoms guided by a hollow optical fiber waveguide is calculated in three dimensions with quantized external motion. The size of the band gap is controlled by the light guided by the fiber. This variable band structure may allow the construction of devices that can cool atoms. The major limitation on this device would be the spontaneous emission losses.