Quantum Correlations and Entanglement in Electromagnetically Induced Transparency System

The quantum correlation and entanglement of an atomic ensemble under the electromagnetically induced transparency (EIT) mechanism are investigated through measurement-induced disturbance (MID) and concurrence, respectively. These quantities are dependent on the Rabi frequency of the driving field, the excitation mode, and the photon and atom numbers of the ensemble. A quantitative relation between MID and concurrence is obtained when the information of the probe field is entirely transferred into the atomic ensemble. In three decoherence channels, sudden vanishing phenomenon of MID do not exist in all decoherence time. Furthermore, MID in the amplitude damping channel shows a stronger survivability than those in the other two decoherence channels. The comparison results of the survivability of MID in the phase damping channel and depolarizing channel are as follows: when the initial value of MID is less than 0.5, then it has stronger survivability in the phase damping channel. Otherwise, it has stronger survivability in the depolarizing channel. However, the sudden death of concurrence in three decoherence channels appears easily. The concurrence generated by the half excited and the low excited modes has the longest and shortest survival time in the amplitude damping channel and the depolarization channel, respectively.