Blinding quantum computation using alternative sources

Quantum computation has seen rapid progress in the past years. Due to implementation complexity and cost, cloud-based quantum computing is strongly believed to be the most feasible framework for individual users. Universal blind quantum computing (UBQC) provides the protocol for secure delegation of arbitrary quantum computations and has received significant attention. However, one of the major challenges in UBQC is a secure and reliable transmission of a quantum state over a long distance. Herein, we improve the efficiency of UBQC using alternative photon sources. Our analysis shows that a heralded single-photon source can significantly improve the transmitted distance of UBQC and a modified coherent source can reduce the required transmitted number of pulses. Furthermore, we study the finite-data-size effect, which is a crucial for real-world applications. Our proposed scheme can be a promising alternative for the future development of UBQC.

Figure 1

(a) Schematic diagram of a UBQC protocol with ideal single-photon source. (b) Schematic diagram of a UBQC protocol with WCP. Considering the redundant information of a multiphoton pulse, the RBSP protocol is applied to remotely prepare a secured qubit. The protocol consists of two key steps. One is to perform the QND measurement of the number of photons at the received pulse to obtain the number of the vacuum pulse $N$ and judge whether the protocol is terminated. The second is the I1DC subroutine for the remaining quantum states. (c) Schematic diagram of a UBQC protocol with an alternative source: decoy-state method. The client requires an intensity modulation module. More interestingly, the I1DC subroutine can be executed in parallel to produce multiple secured qubits simultaneously.

Figure 2

$N$ dependence on $L$. Blue line represents the MCS, the red line denotes WCP. The yellow line represents HSPS with setting the detector efficiency ${\eta }_{\mathrm{c}}=0.1$. The inset shows linear plot over short distance.