Robust Quantum Private Queries

We propose a new quantum private query protocol with the technique of decoherence-free states, which is a theoretical study of how decoherence-free states can be used for the protection of quantum information in such a protocol. This protocol can solve the noise problem that will make the user obtain a wrong answer and hence give rise to a bad influence on the reputation of the database provider. Furthermore, this protocol is also flexible, loss-resistant and easily generalized to a large database similar to the previous works.