  Universal blind quantum computing allows users with minimal quantum resources
to delegate a quantum computation to a remote quantum server, while keeping
intrinsically hidden input, algorithm, and outcome. State-of-art experimental
demonstrations of such a protocol have only involved one client. However, an
increasing number of multi-party algorithms, e.g. federated machine learning,
require the collaboration of multiple clients to carry out a given joint
computation. In this work, we propose and experimentally demonstrate a
lightweight multi-client blind quantum computation protocol based on a novel
linear quantum network configuration (Qline). Our protocol originality resides
in three main strengths: scalability, since we eliminate the need for each
client to have its own trusted source or measurement device, low-loss, by
optimizing the orchestration of classical communication between each client and
server through fast classical electronic control, and compatibility with
distributed architectures while remaining intact even against correlated
attacks of server nodes and malicious clients.

Quantum Physics