Verifying BQP Computations on Noisy Devices with Minimal Overhead

Abstract

With the development of delegated quantum computation, clients will want to ensure confidentiality of their data and algorithms, and the integrity of their computations. While protocols for blind and verifiable quantum computation exist, they suffer from high overheads and from oversensitivity: When running on noisy devices, imperfections trigger the same detection mechanisms as malicious attacks, resulting in perpetually aborted computations. We introduce the first blind and verifiable protocol for delegating BQP computations to a powerful server with repetition as the only overhead. It is composable and statistically secure with exponentially-low bounds and can tolerate a constant amount of global noise.

A Framework for Verifiable Blind Quantum Computation

“…In Section 6, we show how to use the framework to not only recover well-known traps but also construct new ones. Finally, using the latter, we prove in Section 7 that they allow to outperform previous state-of-the-art protocols for verifying BQP computations [17] by reducing the time overhead and increasing their noise robustness.…”

“…Furthermore, while most of these protocols keep the client simple they all have large hardware overheads on the server side. This situation changed recently with the introduction of a robust and efficient protocol for verifying BQP computations in [17]. This protocol provides for the first time robustness to a constant amount of global noise, without any additional space overhead compared to the unverified MBQC computation.…”

“…The only overhead is a polynomial number of repetitions of rounds, each of the same complexity as the unprotected computation. The key features in the protocol of [17] are (i) the way in which the traps are inserted, and (ii) how the detection sensitivity is amplified. Inspired by this work, in the present paper we aim at revisiting trappification-based verification in the MBQC model by introducing a general framework that not only encompasses previous approaches but also considerably simplifies and enlarges the set of techniques that can be used.…”

Divide-and-conquer verification method for noisy intermediate-scale quantum computation

“…Prior to our work, as far as we know, only two types of verification methods were developed for NISQ computers [49][50][51][52]. Our method can estimate the fidelity between ideal and actual output states, unlike the methods in Refs.…”

“…The methods in Refs. [50,52] achieve both verifiability and the security, i.e., they enable us to securely and verifiably delegate quantum computing to a remote server even if the server's quantum computer is noisy. Its error robustness is promising.…”