Quantum computers promise not only to outperform classical machines for certain important tasks, but also to preserve privacy of computation. For example, the blind quantum computing protocol enables secure delegated quantum computation, where a client can protect the privacy of their data and algorithms from a quantum server assigned to run the computation. However, this security comes with the practical limitation that the client and server must communicate after each step of computation. A practical alternative is homomorphic encryption, which does not require any interactions, while providing quantum-enhanced data security for a variety of computations. In this scenario, the server specifies the computation to be performed, and the client provides only the input data, thus enabling secure noninteractive computation. Here, we demonstrate homomorphic-encrypted quantum computing with unitary transformations of individual qubits, as well as multi-qubit quantum walk computations using single-photon states and non-birefringent integrated optics. The client encrypts their input in the photons’ polarization state, while the server performs the computation using the path degree of freedom. Our demonstration using integrated quantum photonics underlines the applicability of homomorphic-encrypted quantum computations, and shows the potential for delegated quantum computing using photons.

量子计算机不仅可以在某些重要任务上胜过传统计算机，而且可以保证计算的私密性。例如，盲量子计算协议支持安全的委托量子计算，其中客户端可以保护其数据和算法的私密性，使其免受分配给运行该量子计算的量子服务器的攻击。但是，这种安全性具有实际限制，即客户端和服务器在计算的每个步骤之后必须进行通信。一种可行的替代方法是同态加密，它不需要任何交互，同时为各种计算提供了量子增强的数据安全性。在这种情况下，服务器指定要执行的计算，而客户端仅提供输入数据，从而实现安全的非交互式计算。这里，我们展示了具有单个量子位的unit元变换的同态加密量子计算，以及使用单光子状态和非双折射集成光学器件的多量子位量子行走计算。客户端在光子的极化状态下加密其输入，而服务器使用路径自由度执行计算。我们使用集成量子光子学的演示强调了同态加密量子计算的适用性，并展示了使用光子进行委托量子计算的潜力。服务器使用路径自由度执行计算。我们使用集成量子光子学的演示强调了同态加密量子计算的适用性，并展示了使用光子进行委托量子计算的潜力。服务器使用路径自由度执行计算。我们使用集成量子光子学的演示强调了同态加密量子计算的适用性，并显示了使用光子进行委托量子计算的潜力。