Entanglement dynamics of three-qubit states in noisy channels

We study entanglement dynamics of the three-qubit system which is initially prepared in pure Greenberger-Horne-Ze linger (GHZ) or W state and transmitted through one of the Pauli channels sigma(z), sigma(x), sigma(y) or the depolarizing channel. With the help of the lower bound for three-qubit concurrence we show that the W state preserves more entanglement than the GHZ state in transmission through the Pauli channel sigma(z). For the Pauli channels sigma(x), sigma(y) and the depolarizing channel, however, the entanglement of the GHZ state is more resistant against decoherence than the W-type entanglement. We also briefly discuss how the accuracy the lower bound approximation depends on the rank of the density matrix under consideration.