  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.

Quantum Physics