Quantum Decoherence and Entanglement in Quantum Information

The study investigated the effects of noise on quantum coherence and quantum entanglement in quantum information through the interaction between an atomic system described by a two or three-level particle and quantized radiation field, which can have one or two modes and that system is coupled to reservoir. The entanglement in the interacting system of a single mode thermal field and a single qubit with dissipation in the dispersive limit was investigated. The effects of thermal photons on entanglement and coherence loss were investigated. It has been found that, the field is inhibited from going into a pure state and coherence is lost faster than in the case of zero temperature. The temporal evolution of entanglement for a single-mode field interacting with a two-level atom via intensity-dependent coupling in the off-resonant case has been studied, where the leakage of photon through the cavity has been taken into account. Based on the master equation for the density matrix, the dynamics of the entanglement of the three-level atom interacting with single-mode field in a finite-Q cavity were studied.