Polarization phase gate and three-photon GHZ state using coherently enhanced Kerr nonlinearity

摘要

We study the nonlinear optical response of a five-level atomic system in the regimes of electromagnetically induced transparency and coherent Raman gain, corresponding to two different schemes of lightatom interaction. Our analytical and numerical results show that greatly enhanced Kerr nonlinearity and efficient cross phase modulation may be achieved between a weak probe field and a weak signal field. The cross phase modulation via Kerr nonlinearity is then exploited toward the realization of a polarization quantum phase gate and the generation of a three-photon GHZ state.