On maximal entanglement between two pairs in four-qubit pure states
Shirley Brierley, Atsushi Higuchi · Journal of Physics A Mathematical and Theoretical · 2007
We show that the state with the highest known average two-particle von Neumann entanglement entropy proposed by Sudbery and one of the authors gives a local maximum of this entropy. We also show that this is not the case for an alternative highly entangled state proposed by Brown et al .