  We investigate the deterministic generation and distribution of entanglement
in large quantum networks by driving distant qubits with the output fields of a
non-degenerate parametric amplifier. In this setting, the amplifier produces a
continuous Gaussian two-mode squeezed state, which acts as a quantum-correlated
reservoir for the qubits and relaxes them into a highly entangled steady state.
Here we are interested in the maximal amount of entanglement and the optimal
entanglement generation rates that can be achieved with this scheme under
realistic conditions taking, in particular, the finite amplifier bandwidth,
waveguide losses and propagation delays into account. By combining exact
numerical simulations of the full network with approximate analytic results, we
predict the optimal working point for the amplifier and the corresponding
qubit-qubit entanglement under various conditions. Our findings show that this
passive conversion of Gaussian- into discrete- variable entanglement offers a
robust and experimentally very attractive approach for operating large optical,
microwave or hybrid quantum networks, for which efficient parametric amplifiers
are currently developed.
