  Quantum logic operations can be implemented using nonlinear phase shifts (the
Kerr effect) or the quantum Zeno effect based on strong two-photon absorption.
Both approaches utilize three-level atoms, where the upper level is tuned on
resonance for the Zeno gates and off-resonance for the nonlinear phase gates.
The performance of nonlinear phase gates and Zeno gates are compared under
conditions where the parameters of the resonant cavities and three-level atoms
are the same in both cases. It is found that the expected performance is
comparable for the two approaches, despite the apparent differences in the way
they are implemented.
