  I analyze an all-optical switching scheme in a cavity QED system consisting
of multiple three-level atoms confined in a cavity mode. A control laser
coupled to the atoms from free space induces quantum interference in the
coupled cavity-atom system and performs all optical switching of the
cavity-atom polaritons. When the cavity is tuned far away from the atomic
resonance, the cavity-atom polariton consists of nearly pure photonic
excitation and then the scheme can be used for photon switching at low light
intensities.
