Role of the Drive in Mediating Correlations Between Two Qubits Through a Shared Dissipative Cavity
Using a numerically exact master equation, we demonstrate that two qubits, coupled solely through a shared damped, driven cavity, can become correlated. The drive influences both the amount and the type of correlation. For parametric, coherent, and resonantly modulated drives, the qubits develop quantum discord that increases with cavity temperature, while the logarithmic negativity remains numerically zero. This indicates the presence of discord without entanglement. In contrast, a time-modulated parametric drive is the only one that generates genuine two-qubit entanglement, achieving \(E_\mathcal{N} \simeq 0.15\) and concurrence \(\simeq 0.16\) at \((\eps, γ) = (0.3, 0.2)\), which rises to \(E_\mathcal{N} \simeq 0.32\) in the weak-coupling, moderate-damping region. Heating eventually destroys this entanglement around \(n_{\mathrm{th}} \simeq 0.2\), while discord continues to grow, resulting in a temperature-driven transition from entanglement to discord within a single drive. Moreover, the parametric drive offers the best protection for single-qubit coherence, unlike the coherent and modulated drives. An adiabatic-elimination model indicates that the cavity generates an effective coupling and a collective dephasing channel, both of which increase with temperature, explaining the observed discord without entanglement.