We study a system composed of four qubits in the presence of two local common
reservoirs, their markovian dissipative dynamics corresponding to that of vacuum
squeezed reservoirs. We consider two maximally entangled qubits AB as the
source, and two maximally entangled qubits A’B’ as the ancillae. The pair AA’
interacts with a common local reservoir in a squeezed vacuum state, characterized
by the squeezing parameters r and ϑ; while the pair BB’ interact with another
reservoir with identical characteristics. The Lindblad master equation is used to
describe the evolution of the whole system, concurrence and fidelity of the source
are computed when measurements are performed on the ancillae at time t. For
given initial conditions, concurrence in the source pair reach a stationary value
different from zero and its fidelity is f > ½ . For some squeezing parameters, a
substantial improvement of the entanglement in the source is obtained compared
with other protocols using independent reservoirs.