Phase damping destroys quantum Fisher information of W states
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CitationÖzaydın, F. (2014). Phase damping destroys quantum fisher information of W states. Physics Letters A, 378(43), 3161-3164. doi:10.1016/j.physleta.2014.08.035
We study the quantum Fisher information (QFI) of W states in the basic decoherence channels. We show that, as decoherence starts and increases, under i) depolarizing, QFI smoothly decays; ii) amplitude damping, QFI first exhibits a sudden drop to the shot noise level, then decreases to zero and finally increases back to the shot noise level; iii) phase damping, QFI is zero for all non-zero decoherence. We also find that on the contrary to GHZ states, QFI of W states in x and y directions are equal to each other and zero in z direction.