通用盲量子計算的分散式架構與容錯

Abstract

通用盲量子計算是量子資訊領域中很吸引人的技術，因為它可以讓具龐大量子計算能力的伺服器運行客戶端指定的任意量子計算，同時可以保護客戶端的隱私，不讓伺服器知道計算的輸入和輸出資料，甚至是計算本身的過程。客戶端可以透過具備有限量子計算能力的小型裝置和量子傳輸通道在量子計算伺服器上進行量子計算，而同時隱藏私密的資料和有價值的量子演算法，其保密性是理論上完美的。然而，錯誤更正及容錯對於盲量子計算系統的實作上是非常重要的。 將量子錯誤更正應用到盲量子計算系統上會帶來很大的負擔。客戶端需要準備更多量子位元也同時消耗更多能源。本文發現將量子錯誤更正實行在通用盲量子計算協定的下層比將量子錯誤更正實行在通用盲量子計算協定的上層可以使用更少的計算資源來完成，只需要客戶端具備小型量子計算的能力。本論文中也提出改良的通用盲量子計算協定，讓客戶端可以不具備量子計算能力，只需要量子位元暫存的能力也可以完成。此外，本文也分析了所提出的容錯通用盲量子計算協定的計算與通訊的成本。 為了突破盲量子計算在計算大小的限制，本文中提出盲量子計算的分散式架構，使一個盲量子計算可以被拆成數個小的計算區塊，再由數個伺服器來進行計算。另外本論文也提出進行通用盲量子計算的另一種方法，基於量子遙傳的方法。這方法在分散式盲量子計算很有幫助，因為它可同時完成量子遙傳和盲量子計算，此外其計算是由多個小計算單位組成。

Blind quantum computation is an appealing use of quantum information technology because it can make the server with large computational capability perform an arbitrary quantum computation assigned by the client and protect client's privacy by concealing the input, output, and even the computation itself from the server. The client can use a small device with limited quantum computing capacity and quantum communication channel to perform a quantum computation on a quantum computing server while concealing the private data and the valuable quantum algorithm with theoretically perfect security. However, error-correction and fault-tolerance are very important to the practical implementation of the blind quantum computation system. Applying quantum error correction to the blind quantum computation system brings both the client and the server a lot of overhead. The client needs to prepare more qubits and cost more energy. Applying quantum error correction in the bottom of the blind quantum computation protocol costs less qubits than applying quantum error correction on top of the blind quantum computation protocol. In this paper, a new blind quantum computation protocol which costs the client less computational effort is proposed. On the other hand, the server's computational effort is increased when performing fault-tolerant blind quantum computation. To break the limit of the computational size in the blind quantum computation, a distributed architecture for blind quantum computation is proposed in this paper. A whole blind quantum computation can be divided into multiple smaller computation parts, which can be performed by multiple server. This paper also shows a different kind of universal blind quantum computation protocol based on quantum teleportation. It is useful in a distributed blind quantum computation because quantum communication and blind quantum computation are performed at the same time and the computation is composed of small computation units.