Summary form only given. Linear and nonlinear atomic response can be manipulated by quantum interference in an atomic medium in which electromagnetically induced transparency (EIT) is created by a coherent coupling field. Recently Agarwal and Harshawardhan showed that two-photon absorption may be enhanced or suppressed by quantum interference in a ladder-type atomic system (Phys. Rev. Lett. vol. 77, p. 1039, 1996). We report an experimental demonstration of two-photon suppression by quantum interference in 87Rb atoms cooled and confined in a magneto-optical trap (MOT).
