Quantum‐Key‐Distribution‐Based Quantum Private Query with Phase Encoding

Quantum private query (QPQ) as the quantum version of the symmetrically private information retrieval problem, is recognized as a new quantum cryptographic protocol with great practical potential. Compared to classical schemes, QPQ protocols provide higher security and lower complexity. However, most of the existing protocols are polarization encoding ones, which are incompatible with current optical fiber communication quantum networks. Moreover, the high demands for quantum capabilities and the scarcity of affordable quantum resources present challenges. This paper proposes a QPQ protocol with phase encoding of two‐way communication, enhancing the stability and reducing quantum resources expenditure. The security analysis demonstrates that this protocol is capable of effectively resisting several common attacks, safeguarding the privacy security of the database and user. Furthermore, the protocol has the potential to be implemented in existing phase‐encoding quantum systems, promoting progress in the practical application of QPQ.