N-qubit entanglement via the $J_y^2$-type collective interaction
  We investigate quantum correlations of the $N$-qubit states via a collective pseudo-spin interaction ($\propto J_y^2$) on arbitrary pure separable states for a given interval of time. Based on this dynamical generation of the $N$-qubit maximal entangled states, a quantum secret sharing protocol with $N$ continuous classical secrets is developed. 
D.L. Zhou, B. Zeng, J.S. Tang, Z. Xu, and L. You