Recently, Gao et al. suggested a flexible quantum private query (QPQ) protocol (Opt Express, 2012, 20(16):17411) through Jakobi et al.’s quantum-key-distribution based QPQ protocol (Phys Rev A, 2011, 83:022301). Inspired by Gao et al.’s QPQ protocol, we design a multi-user QPQ protocol by using the product states of single-photon states. Its database privacy and user privacy should be compromised by choosing an suitable value for θ. Due to the honesty check process for the database owner, an smaller θ can be priorly chosen to guarantee better database privacy. Moreover, it naturally inherits some good characteristics of Gao et al.’s QPQ protocol so that it is also loss-tolerant, practical to huge-database condition, robust against quantum memory attack and flexible. It differs from Gao et al.’s QPQ protocol on three aspects: firstly, it adds the process of checking the presence of an illegal eavesdropper; secondly, it adds the process of checking the database owner’s honesty; and finally, it is feasible for n users to query the items of database simultaneously.

中文翻译：

---

多用户量子私有查询协议

最近，高等人。通过 Jakobi 等人的基于量子密钥分发的 QPQ 协议（Phys Rev A，2011，83：022301），提出了一种灵活的量子私有查询 (QPQ) 协议（Opt Express，2012，20（16）：17411）。受 Gao 等人的 QPQ 协议的启发，我们利用单光子状态的乘积状态设计了一个多用户 QPQ 协议。应通过为 θ 选择合适的值来损害其数据库隐私和用户隐私。由于数据库所有者的诚实检查过程，可以预先选择较小的 θ 以保证更好的数据库隐私。而且，它自然继承了高等人的QPQ协议的一些良好特性，因此它也具有容错性、对大数据库条件的实用性、对量子存储器攻击的鲁棒性和灵活性。它在三个方面与 Gao 等人的 QPQ 协议不同：第一，它增加了检查非法窃听者存在的过程；其次，增加了检查数据库所有者诚实度的过程；最后，n个用户可以同时查询数据库的项目。