Laser cooling in a trap is investigated for laser and trapping configurations which allow the existence of approximate ‘‘dark states’’ of the combined atom-plus-trap system, i.e., states that are decoupled from the laser light by quantum interference. We show that a one-dimensional (1D) free-particle dark state in angular momentum ${\mathit{J}}_{\mathit{g}}$=1 to ${\mathit{J}}_{\mathit{e}}$=1 transitions and in two counterpropagating laser fields survives as an approximate dark state in a ‘‘flat-bottom’’ trap of size much larger than the optical wavelength. Furthermore, we show the existence of approximate dark states in 1D harmonic-oscillator potentials. In the latter configuration we are able to provide analytical results.

• Received 2 June 1995

DOI:https://doi.org/10.1103/PhysRevA.52.4709