Entanglement Generation in a Two-Qubit System Coupled to Vacuum Electromagnetic Field

The entanglement generation in a two-qubit system interacting with electromagnetic vacuum field and an external local magnetic field is investigated in the framework of the master equation. The time-evolution for the most general density matrix of the two-qubit system is obtained and solved. It is shown that the two-qubit system ends up in an entangled stationary state independent on the initial separable state.