Entanglement swapping in presence of dephasing

Entanglement which originates from a pair of non-interacting qubits by means of entanglement swapping is discussed when dephasing mechanisms are present. Then, the exact reduced dynamics can be evaluated for two pairs of independent qubits which each are coupled to their own bosonic environment. Each of two pairs of qubits is initially maximally entangled. The conditions for the entanglement survival at asymptotic long times in terms of environment spectral properties are elaborated. It is shown that these conditions hold true also for the inter-pair entanglement stemming. Entanglement swapping can effectively been controlled by a proper choice of initial state of the finite environment. [GRAPHICS] Two non-interacting pairs of qubits, {S(1), S(2)} and {S(3), S(4)}, are in a separable state, wherein each pair of qubits is maximally entangled. The Bell state measurement (BSM) on the pair {S(2), S(4)} creates the entanglement of the qubits S(1) and S(3). The qubits are coupled to their own environments R(i), i = 1, ..., 4. (C) 2009 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim