Unambiguous discrimination of extremely similar states by a weak measurement

In this paper, we propose a method to discriminate two extremely similar quantum states via a weak measurement. For the two states with equal prior probabilities, the optimum discrimination probability given by Ivanovic-Dieks-Peres limit can be achieved by our protocol with an appropriate choice of the interaction strength. However, compared with the conventional method for state discrimination, our approach shows the advantage of error-tolerance by achieving a better ratio of the success probability to the probability of error.