Secure delegated quantum computation based on Z-rotation encryption

¹ State Key Laboratory of Integrated Services Networks, Xidian University - Xi'an, Shaanxi 710071, China
² Collaborative Innovation Center of Quantum Information of Shaanxi Province, Xidian University Xi'an, Shaanxi 710071, China
³ Shaanxi Key Laboratory of Information Communication Network and Security, Xi'an University of Posts and Telecommunications - Xi'an, Shaanxi 710121, China
⁴ School of Communications and Information Engineering, Xi'an University of Posts and Telecommunications Xi'an, Shaanxi 710121, China

^(a) chhzhu@xidian.edu.cn (corresponding author)

Received: 11 November 2021
Accepted: 28 January 2022

Abstract

Quantum computing on encrypted data allows a client who has limited quantum capacity to delegate his or her private computation to an untrusted quantum server, while the input and output are encrypted by the quantum one-time pad and only the client can correctly decrypt them. Generally, the client is required to have ability to prepare some single qubits and perform some basic gates. In this work, we consider a further restricted situation where the client can only prepare one single qubit and perform one basic gate. Specifically, we show that as long as the client can prepare a fixed qubit |+⟩ and perform a fixed phase gate P, then he or she can still achieve the secure delegated quantum computation. Besides, our protocol can provide a more rigorous security for any quantum computation. For example, even if some encryption keys about the computation are leaked, it can still guarantee the privacy of the input and output. Finally, our protocol experimentally has a great significance in reducing the device complexity of the client's side.