Key points are not available for this paper at this time.
We propose an efficient method to construct an optical four-photon |χ〉 state analyzer via the cross-Kerr nonlinearity combined with linear optical elements. In this protocol, two four-qubit parity-check gates and two controlled phase gates are employed. We show that all the 16 orthogonal four-qubit |χ〉 states can be completely discriminated with our apparatus. The scheme is feasible and realizable with current technology. It may have useful potential applications in quantum information processing which based on |χ〉 state.
Zeng et al. (2015) studied this question.