Spin squeezing under non-Markovian channels by the hierarchy equation method

We study the decoherence of spin squeezing under non-Markovian channels and consider an ensemble of N independent spin-1/2 particles with exchange symmetry. Each spin interacts with its own bath, and the baths are independent and identical. For this kind of open system, the spin squeezing under decoherence can be investigated from the dynamics of the local expectations. The reduced dynamics is obtained by the exact hierarchy equation method. The numerical results show that the spin squeezing may display both sudden and asymptotic vanishing; however, the revival phenomenon does not happen. In contrast, the concurrence shows multiple sudden vanishing and revival phenomena.