Flexible blind quantum computation with unnecessarily universal quantum servers

Abstract

Blind quantum computation (BQC) allows clients with limited quantum capabilities to delegate their tasks to powerful quantum servers and still keep their inputs, algorithms, and outputs private. However, in the noisy intermediate-scale quantum (NISQ) era, quantum computers as servers only control limited number of qubits and are not powerful enough. In addition, each of current BQC models is usually suitable for only one type of users. Therefore, this paper offers a flexible BQC ( for short) model for two types of users with different quantum capabilities where any one of two types of users can complete BQC tasks with the help of the other type of users and quantum servers. To be more specific, we propose two protocols by using the given model. In the first protocol, one user Alice only with the ability to prepare single-qubit states can realize BQC tasks by cooperating with another user Bob who is just capable of performing single-qubit measurements and a quantum server Charlie. Similarly in the second one, Bob can realize BQC tasks by cooperating with Alice and Charlie. In both protocols, the server Charlie only requires a quantum register of small size and performing CZ gates and thus it is unnecessary to be universal and may be less difficult to realize in the short run. Furthermore, both proposed protocols are verifiable, namely that the user can detect whether the server is honest. Finally, examples of the proposed protocols for implementing Deutsch’s algorithms are simulated through Qiskit framework to show their feasibility and correctness.