  Cavities embedded in photonic crystal waveguides offer a promising route
towards large scale integration of coupled resonators for quantum
electrodynamics applications. In this letter, we demonstrate a strongly coupled
system formed by a single quantum dot and such a photonic crystal cavity. The
resonance originating from the cavity is clearly identified from the
photoluminescence mapping of the out-of-plane scattered signal along the
photonic crystal waveguide. The quantum dot exciton is tuned towards the cavity
mode by temperature control. A vacuum Rabi splitting of ~ 140 \mueV is observed
at resonance.
