Frequency-modulated qubits in a dissipative cavity: entanglement dynamics and protection

We address the problem of preserving entanglement in open quantum systems specifically two-qubit system via devising a new strategy in which a structured environment and modulation mechanism cooperatively benefit the whole system. The model is quite general and encompasses any two arbitrary qubits whether the same or different with various modulation parameters. Hence, we consider two more plausible scenarios once with similar qubits and once again with dissimilar qubits. For the special case when the system possesses two similar qubits, we investigate the dynamics of entanglement in the presence (resonance) and absence of detuning (non-resonance) for both weak and strong coupling regimes. It is revealed that there are optimal modulation parameters and detuning for which the maximal protection and generation of entanglement are achieved. Finally, we consider a more general scenario for which the qubits can have different transition frequencies. It is observed that with the optimal choices of the detuning parameters as well as the modulation parameters one shall attain a nearly perfect protection.