Decoy-state quantum-key-distribution-based quantum private query with error tolerance bound

Quantum private query (QPQ) faces many challenges in practical applications. At present, some scholars have made substantial work on overcoming channel loss, channel noise, and nonideal light sources, respectively. However, a protocol that would overcome all three of these problems has yet to materialize. We review a practical QPQ protocol that can actually work in noisy channels. This protocol has an upper bound on tolerable errors based on the required level of security and reliability. Then, we study the security of the above QPQ protocol under weak coherent pulses. The results indicate that the multiphoton pulses have induced significant vulnerabilities, which seriously threatens the privacy of users. Finally, we propose a decoy-state method to solve the serious threat to user security caused by multiphoton pulses. The analysis shows that the decoy-state method significantly improves the security of the QPQ protocol under weak coherent pulses. The improved protocol can not only tolerate transmission losses and channel noise, but also overcome the security vulnerability caused by a nonideal light source.