Geometric measure of entanglement of symmetric d-qubits is   polynomial-time computable
  We give a simple formula for finding the spectral norm of d-mode symmetric tensor in two variables over the complex or real numbers in terms of the complex or real roots of a corresponding polynomial in one complex variable. This result implies that the geometric measure of entanglement of symmetric d-qubits is polynomial-time computable. We discuss a generalization to d-mode symmetric tensor in more than two variables. 
Shmuel Friedland and Li Wang
math.RA math-ph math.MP quant-ph