Project supported by the National Natural Science Foundation of China (Grant No. 10804042);supported by the Scientific Research Foundation of the Education Department of Jiangxi Province,China (Project No. GJJ09440)
Two closest single-qubit states could be diagonalised by the same unitary matrix, which helps to find the relative entropy of entanglement of a two-qubit 'X' state. We formulate two binary equations for the relative...