Quantum private query (QPQ) is a kind of secure information retrieve protocol, in which both user and database privacy can be protected. Previous QPQ protocols generally consider one user retrieving and need to be performed repeatedly between each user and the database provider when multiple users want to retrieve information from a database. This work focuses on a particular scenario, where multiple users work together to accomplish a task and need to securely query the same item from a database, and proposes a multi-user QPQ protocol using entanglement swapping technology of multi-particle GHZ state. The security analysis shows that the user and database privacy are both guaranteed by real-time security detection.

中文翻译：

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多用户量子私有查询

量子专用查询（QPQ）是一种安全的信息检索协议，该协议可以保护用户和数据库隐私。先前的QPQ协议通常考虑一个用户的检索，并且当多个用户想要从数据库中检索信息时，需要在每个用户和数据库提供者之间重复执行。这项工作着重于一个特定的场景，其中多个用户共同完成一项任务，需要从数据库中安全地查询同一项目，并提出了一种使用多粒子GHZ状态的纠缠交换技术的多用户QPQ协议。安全分析表明，实时安全检测可确保用户和数据库的隐私。