  We discuss quantum interference effects in a three-level atom in
lambda-configuration, where both transitions from the upper state to the lower
states are driven by a single monochromatic laser field. Although the system
has two lower states, quantum interference is possible because there are
interfering pathways to each of the two lower states. The additional
interference terms allow for interesting effects such as the suppression of a
dark state which is present without the interference. Finally we examine a
narrow spectral feature in the resonance fluorescence of the atom with quantum
interference.
