  We investigate the tunable quantum entanglement and the probabilities of
excitations in a system of three qubits in a non-stationary cavity due to the
dynamical Lamb effect, caused by non-adiabatic 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 have been evaluated. The
conditional concurrence and the conditional residual tangle for each fixed
amount of created photons are introduced and calculated as measures of the
pairwise or three-way dynamical quantum entanglement of the qubits. We also
give a prescription on how to increase the values of those quantities by
controlling the frequency of the cavity photons. A physical realization of the
system with three superconducting qubits, coupled to a coplanar waveguide
entangled due to the non-adiabatic fast change of boundary conditions of the
cavity is proposed.
