Positive impact of decoherence on spin squeezing in GHZ and W states

We study spin squeezing behaviour in tripartite unsqueezed maximally entangled Greenberger–Horne–Zeilinger (GHZ) and W states under various decoherence channels with Kitagawa–Ueda criteria. In order to search spin squeezing sudden death (SSSD) and perform the analysis of spin squeezing production we use bit flip, phase flip, bit-phase-flip, amplitude damping, phase damping and depolarization channels in the present study. In literature, the influence of decoherence has been studied usually as a destroying element. On the contrary here we investigate the positive impact of decoherence, which produces spin squeezing in unsqueezed GHZ and W states under certain channels. Our careful study shows that GHZ state remains unsqueezed under aforementioned channels except bit-phase-flip and depolarization channels, on the other hand all the decoherence channels produce spin squeezing in W state. So we find that, GHZ is more robust in comparison to W state in the sense of spin squeezing production under decoherence. Most importantly we find, none of the decoherence channels produce SSSD in either of the states. (paper)