Controlling entanglement sudden death in two coupled atoms interacting off-resonance with a radiation field

We study a system of two coupled two-level atoms (qubits) interacting, at non-zero detuning, with a single mode radiation field. This system is of special interest in the field of quantum information processing (QIP) and can be realized in electron spin states in quantum dots or Rydberg atoms in optical cavities and superconducting qubits in linear resonators. We utilize our exact analytical solution for the time evolution of the system to show how entanglement sudden death (ESD), which represents a major threat to QIP, can be efficiently controlled by tuning atom-atom coupling and non-zero detuning. We demonstrate that while one of these two system parameters may not separately affect the ESD, combining the two can be very effective in reducing, eliminating or creating ESD depending crucially on the system initial state. A synchronization between the population inversion collapse-revival pattern and the entanglement dynamics is observed at all system parameter combinations. The variation of the radiation field intensity shows a clear impact on the duration of the ESD at any combination of the other system parameters.