Maximally Entangled Mixed States in two Qubits
Satoshi Ishizaka, Tohya Hiroshima · Kluwer Academic Publishers eBooks · 2006
We propose novel mixed states in two qubits, which have a property that the amount of entanglement of these states cannot be increased by any unitary transformation. The corresponding entanglement of formation specified by its eigenvalues gives an upper bound of that for density matrices with the same eigenvalues.