Practically verifiable blind quantum computation with acceptance rate amplification

Research paper by Yuki Takeuchi, Keisuke Fujii, Tomoyuki Morimae, Nobuyuki Imoto

Indexed on: 06 Jul '16Published on: 06 Jul '16Published in: Quantum Physics


Blind quantum computation (BQC) allows a client, who only possesses relatively poor quantum devices, to delegate universal quantum computation to a server, who has a fully fledged quantum computer, in such a way that the server cannot know the client's input, quantum algorithm, and output. In the existing verification schemes of BQC, any suspicious deviation on the trap qubits is rejected, and hence the acceptance rate of the output decreases exponentially in the number of trap qubits even under not malicious server's deviation or quantum channel noise. This degrades the practicability of the verifiable BQC protocol. To avoid this, we here propose a remote blind single-qubit preparation protocol, where the client performs only Pauli X- and Z-basis measurements to prepare the random states required for the FK protocol. While the quantum server can prepare any malicious state for the client, we show that any client's information is blind for the server and that any server's deviation is independent on the state send by the client, which is necessary to guarantee blindness and verifiability of the proposed protocol. Since only $X$ and $Z$-basis measurements are employed, the client can reduce the error by using only classical processing with the CSS (Calderbank-Shor-Steane) codes. This allows almost classical client to amplify the acceptance rate even under server's deviation or quantum channel noise, as long as they are correctable.