Mutual preservation of entanglement

We study a generalized double Jaynes–Cummings (JC) model where two entangled pairs of two-level atoms interact indirectly. We show that there exist initial states of the qubit system so that two entangled pairs are available at all times. In particular, the minimum entanglement in the pairs as a function of the initial state is studied. Finally, we extend our findings to a model consisting of multi-mode atom–cavity interactions. We use a non-Markovian quantum state diffusion (QSD) equation to obtain the steady-state density matrix for the qubits. We show that the multi-mode model also displays dynamical preservation of entanglement.

► Entanglement dynamics is studied in a generalized double Jaynes–Cummings model.
► We show that for certain initial states, the atoms remain entangled at all times.
► We extend the results to the case of multi-mode atom–cavity interactions.
► The model suggest that indirect interaction may help to preserve entanglement.