Optimal Linear Optical Discrimination of Bell-Like states
Dov Fields, Vladimir S. Malinovsky, János A. Bergou, Mark S. Hillery · 2021
One major challenge in utilizing linear optical setups for quantum computing, is that only a limited set of operations can be preformed. Achieving universal quantum computing using only linear optical components comes at the cost of either requiring an untenable number of ancillary photons or the acceptance of some probability of failure. Understanding the constraints and optimizing general linear optical operations under these constraints is both an important and challenging task. Here we consider the problem of perfectly discriminating between Bell-like states without the use of ancillary photons. For the discrimination between Bell states, the optimal success probability cannot exceed 50%. Here we derive the optimal approach for Bell-like states and show that the success probability without ancillary photons can only reach 25%.