Quantum private queries

TL;DR

This paper introduces a quantum protocol for private database queries that ensures user privacy, database privacy, and reduces communication and computational complexity exponentially compared to existing methods.

Contribution

It presents a cheat-sensitive quantum protocol for private search that is highly efficient and guarantees perfect data privacy, outperforming classical and other quantum strategies.

Findings

Achieves exponential reduction in communication complexity.

Ensures perfect data privacy of the database.

Allows user to detect if the server tries to gain information.

Abstract

We propose a cheat sensitive quantum protocol to perform a private search on a classical database which is efficient in terms of communication complexity. It allows a user to retrieve an item from the server in possession of the database without revealing which item she retrieved: if the server tries to obtain information on the query, the person querying the database can find it out. Furthermore our protocol ensures perfect data privacy of the database, i.e. the information that the user can retrieve in a single queries is bounded and does not depend on the size of the database. With respect to the known (quantum and classical) strategies for private information retrieval, our protocol displays an exponential reduction both in communication complexity and in running-time computational complexity.