We model an optical implementation of a CSIGN gate that makes use of the
Quantum Zeno effect [1,2] in the presence of photon loss. The raw operation of
the gate is severely affected by this type of loss. However, we show that by
using the same photon loss codes that have been proposed for linear optical
quantum computation (LOQC), the performance is greatly enhanced and such gates
can outperform LOQC equivalents. The technique can be applied to other types of
nonlinearities, making the implementation of nonlinear optical gates much more
attractive