Complete N-Qubit Greenberger–Horne–Zeilinger States Analysis Assisted by Frequency Degree of Freedom

We present an efficient and simple protocol to unambiguously distinguish 2Nmutual orthogonal N-qubit Greenberger–Horne–Zeilinger states in polarization degree of freedom assisted by the frequency one. This scheme is based on N single photon Bell state measurements, which can be implemented non-locally. The success probability is100% in principle and our scheme is feasible with current technology. All the advantages make our protocol meaningful and practical in quantum information processing.