Robustness and device independence of verifiable blind quantum computing

TL;DR

This paper proves the robustness of a verifiable blind quantum computing protocol under general conditions, enabling its composition with device-independent state tomography and improving verification efficiency and fault tolerance.

Contribution

It establishes the robustness of a key quantum verification protocol in the most general scenario, facilitating its practical application and composability with other protocols.

Findings

Proved robustness of the Fitzsimons-Kashefi protocol in adversarial scenarios.

Developed a device-independent state tomography protocol based on CHSH game rigidity.

Achieved lower round complexity and fault tolerance in quantum server verification.

Abstract

Recent advances in theoretical and experimental quantum computing bring us closer to scalable quantum computing devices. This makes the need for protocols that verify the correct functionality of quantum operations timely and has led to the field of quantum verification. In this paper we address key challenges to make quantum verification protocols applicable to experimental implementations. We prove the robustness of the single server verifiable universal blind quantum computing protocol of Fitzsimons and Kashefi (2012) in the most general scenario. This includes the case where the purification of the deviated input state is in the hands of an adversarial server. The proved robustness property allows the composition of this protocol with a device-independent state tomography protocol that we give, which is based on the rigidity of CHSH games as proposed by Reichardt, Unger and Vazirani (2013). The resulting composite protocol has lower round complexity for the verification of entangled quantum servers with a classical verifier and, as we show, can be made fault tolerant.