  We report the efficient coherent photon scattering from a semiconductor
quantum dot embedded in a pillar microcavity. We show that a surface acoustic
wave can periodically modulate the energy levels of the quantum dot, but has a
negligible effect on the cavity mode. The scattered narrow-band laser is
converted to a pulsed single-photon stream, displaying an anti-bunching dip
characteristic of single-photon emission. Multiple phonon sidebands are
resolved in the emission spectrum, due to the absorption and emission of
vibrational quanta in each scattering event.
