  As an important branch of quantum secure multiparty computation, quantum
private comparison (QPC) has attracted more and more attention recently. In
this paper, according to the quantum implementation mechanism that these
protocols used, we divide these protocols into three categories: The quantum
cryptography QPC, the superdense coding QPC, and the entanglement swapping QPC.
And then, a more in-depth analysis on the research progress, design idea, and
substantive characteristics of corresponding QPC categories is carried out,
respectively. Finally, the applications of QPC and quantum secure multi-party
computation issues are discussed and, in addition, three possible research
mainstream directions are pointed out.
