“…Thus, so-called unambiguous discrimination strategy is introduced for quantum states which are not necessarily mutually orthogonal [2], [3], [4], [5], [6], [7], [? ], [10], [11], [12], [13], [14]. In contrast to perfect discrimination where one can always identify the state, unambiguous discrimination guarantees that except for an inconclusive probability, one can always get the correct state with zero error probability.…”