Maximal and total skew information for a two-qubit system using nonlinear interaction models

Maximal and total skew information is studied. For symmetric pure states of two-qubit, they are closely related to the linear entropy, the concurrence, and the spin squeezing parameter. For a two-qubit system implemented in three nonlinear interaction models with an external field, we give the exact state vectors and the expectation value 〈S_z〉 at any time t. Based on 〈S_z〉², we give the maximal and the total skew information and a condition in which the maximal and the total skew information can reach 1 and 2, respectively.