Addendum: Extracting an entangled state ofn−tqubits from ann-qubit entangled state after errors attsites

Abstract

We present a detailed study of the method recently proposed by Yang and Gea-Banacloche [Phys. Rev. A 64, 032309 (2000)] to protect a maximally entangled state of n atomic qubits against spontaneous-emission-induced decoherence. We compare this to an approach based on nonradiative states, in the case where the number of thermal photons in the environment is nonzero.