Constraints on the uncertainties of entangled symmetric qubits
  We derive necessary and sufficient inseparability conditions imposed on the variance matrix of symmetric qubits. These constraints are identified by examining a structural parallelism between continuous variable states and two qubit states. Pairwise entangled symmetric multiqubit states are shown here to obey these constraints. We also bring out an elegant local invariant structure exhibited by our constraints. 
A. R. Usha Devi, M. S. Uma, R. Prabhu and A. K. Rajagopal