Demonstration of Blind Quantum Computing (Ohne Sprachangabe)

While quantum computers offer speed advantages over their classical counterparts, the technological challenges facing their eventual realization suggest that they will need to be located in specialized facilities. Thus, interaction would then need to be on a quantum client:quantum server basis. Barz et al. (p. 303; see the Perspective by Vedral) implemented a proof-of-principle protocol that illustrates complete security in such a setup—for both the client and the server. In this blind quantum computing protocol, the client maintains the security of their data and the specifics of the calculation they want to perform, and the server cannot access the data or calculation of the client.

A protocol is implemented that can ensure secure client-server interactions on a quantum computer architecture.

Quantum computers, besides offering substantial computational speedups, are also expected to preserve the privacy of a computation. We present an experimental demonstration of blind quantum computing in which the input, computation, and output all remain unknown to the computer. We exploit the conceptual framework of measurement-based quantum computation that enables a client to delegate a computation to a quantum server. Various blind delegated computations, including one- and two-qubit gates and the Deutsch and Grover quantum algorithms, are demonstrated. The client only needs to be able to prepare and transmit individual photonic qubits. Our demonstration is crucial for unconditionally secure quantum cloud computing and might become a key ingredient for real-life applications, especially when considering the challenges of making powerful quantum computers widely available.