Dynamics of entanglement and quantum Fisher information for N-level atomic system under intrinsic decoherence

Abstract

We present a general problem of quantum entanglement quantified by von Neumann entropy for N-level atomic system. Time evolution of state vector of the entire system is investigated numerically under the influence of intrinsic decoherence for moving three-, four- and five-level atoms. It is seen that the phase shift estimator parameter, intrinsic decoherence and the atomic motion play very important role during the time evolution of the atomic systems. There is a monotonic relation between the atomic quantum Fisher information and entanglement in the absence of atomic motion. It is seen that the local maximum values at the revival time of both QFI and $$S_{A}$$SA decreases gradually during its time evolution. It decreases more rapidly in case of four- and five-level atoms as compared to the three-level atoms. A periodic behaviour of QFI is seen in the presence of atomic motion which becomes more prominent for higher-dimensional systems. However, atomic quantum Fisher information and entanglement exhibit an opposite behaviour during its time evolution in the presence of atomic motion. The evolution of the entanglement is found to be very prone to the intrinsic decoherence. Dramatic change takes place in the degree of entanglement when the intrinsic decoherence increases. Intrinsic decoherence in the atom-field interaction suppresses the nonclassical effects of the atomic systems. The entanglement and Fisher information saturate to its lower level for longer timescales in the presence of intrinsic decoherence. It leads to the sudden death of entanglement for higher values of intrinsic decoherence. However, the damping behaviour of entanglement remains independent of the system dimensions at larger timescales.