  We show that the noise threshold for optical quantum computing can be
significantly improved by using the EPR-type of photon source. In this
implementation, the detector efficiency $\eta_{d}$ is required to be larger
than 50%, and the source efficiency $\eta_{s}$ can be an arbitrarily small
positive number. This threshold compares favorably with the implementation
using the single-photon source, where one requires the combined efficiency
$\eta_{d}\eta_{s}>2/3$. We discuss several physical setups for realization of
the required EPR photon source, including the photon emitter from a single-atom
cavity.
