We investigate the time evolution of pairwise entanglement between two Tavis–Cummings atoms for various entangled initial states, including pure and mixed states. We find that the phenomenon of entanglement sudden death behaviors is distinct in the evolution of entanglement for different initial states. What deserves mentioning here is that the initial portion of the excited state in the initial state is responsible for the sudden death of entanglement, and the degree of this effect also depends on the initial states.
This paper characterizes a quantum correlation formed in an ensemble of atomic two-level systems that stores a narrow-band squeezed state of light by coherently trapping an electron in an atomic superposed state
a∣1⟩+b∣0⟩. In the storage process, a photonic quantum correlation in the squeezed light is transformed into an atomic quantum correlation between
N atoms in an adiabatic way. If we regard the atomic superposed state as a 1/2-spin state and adopt the framework of a pairwise spin entanglement to analyze the atomic quantum correlation, we can identify a certain entangled state of a spin pair as the atomic signature of the squeezed light. The pairwise spin entangled state reflects all the physical properties of the squeezed light. By following the dissipative time evolution in the pairwise entangled state, we can describe the degraded properties of the squeezed light in retrieval.