Hermitian tensor product approximation of complex matrices and separability

Approximation of matrices to the sum of tensor products of Hermitian matrices is studied. A minimum decomposition of matrices on tensor space H 1 ⨂ H 2 in terms of the sum of tensor products of Hermitian matrices on H 1 and H 2 is presented. From this construction the separability of quantum states is discussed. [Copyright &y& Elsevier]