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| We present a flexible quantum-key-distribution-based protocol for quantum private queries. Similar to M. Jakobi et al's protocol [Phys. Rev. A extbf{83}, 022301 (2011)], it is loss tolerant, practical and robust against quantum memory attack. Furthermore, our protocol is more flexible and controllable. We show that, by adjusting the value of $ heta$, the average number of the key bits Alice obtains can be located on any fixed value the users wanted for any database size. And the parameter $k$ is generally smaller (even $k=1$ can be achieved) when $ heta<pi/4$, which implies lower complexity of both quantum and classical communications. Furthermore, the users can choose a smaller $ heta$ to get better database security, or a larger $ heta$ to obtain a lower probability with which Bob can correctly guess the address of Alice's query. |
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| Keywords:Quantum computation, Quantum information, Private queries, Quantum key distribution |
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