  We present a simple technique to reduce the emission rate of higher-order
photon events from pulsed spontaneous parametric down-conversion. The technique
uses extra-cavity control over a mode locked ultrafast laser to simultaneously
increase repetition rate and reduce the energy of each pulse from the pump
beam. We apply our scheme to a photonic quantum gate, showing improvements in
the non-classical interference visibility for 2-photon and 4-photon
experiments, and in the quantum-gate fidelity and entangled state production in
the 2-photon case.
