Tuning the quantum entanglement of three qubits in a nonstationary cavity

We investigated the tunable quantum entanglement and the probabilities of excitations in a system of three qubits in a nonstationary cavity. The entanglement between the qubits arises because of the dynamical Lamb effect, a novel quantum phenomenon caused by nonadiabatic fast change of the boundary conditions of the cavity. The transition amplitudes and the probabilities of excitation of qubits due to the dynamical Lamb effect were evaluated. Furthermore, we introduced the conditional concurrence and the conditional residual tangle for each fixed number of created photons in the cavity as measures of the pairwise or three-way dynamical quantum entanglement of the qubits. A prescription on how to increase the values of those quantities by controlling the frequency of the cavity photons was found. A physical realization of the system using superconducting qubits coupled to a coplanar waveguide terminated by a superconducting quantum interference device is proposed.