The entanglement and second-order coherence function in a two-atom nonlinear Jaynes-Cummings model

The influence of the Kerr nonlinearity on the two two-level atoms entanglement is investigated in Jaynes-Cummings model (JCM), so that one of atoms is inside the cavity field and the other atom is outside it. We show that the entanglement of atoms increases with the decrease of the phase decoherence rate or Kerr coefficient, when considering the effect of external environment. Then due to the statistic properties of the anti-bunching effect of photons are related to entanglement, the nonlinear JCM is examined theoretically to analyze the bunching or anti-bunching effect by using the second-order coherence function. We find that the second-order coherence function decreases with the Kerr coefficient. Our results show that the field reflects the stronger bunching effect with the bigger average photon number.