Sparse and trapping dressed states in a quasicontinuum system

The authors study a quasicontinuum system for which there exists a sparse dressed state composed of the ground state and a single state of the true continuum. In general, the loss of population from the ground state to a true continuum via the quasicontinuum is total. In a special case, however, population is trapped in the ground state and the sparse dressed state is replaced by a trapping state containing no contribution from the true continuum.