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arXiv · 2606.25690

Quantum steering in networks: Measurement-device-independent detection, continuous variables, and practical Gaussian schemes

Shao-Hua Hu·Chung-Yun Hsieh·Huan-Yu Ku·Ray-Kuang Lee·Paolo Abiuso
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Abstract

We consider quantum steering certification in multipartite networks, with a focus on minimal trust scenarios: all-except-one parties are untrusted and treated device-independently. We show that it is always possible to lift steering certification to the measurement-device-independent regime, in which even the (last) trusted party can treat their local hardware as a black-box, except for a set of fiduciary quantum states used as the inputs to the experiment. This holds both for finite-dimensional systems as well as for bosonic continuous-variable systems, for which we provide a full characterization in the bipartite case. Additionally, we introduce measurement-device-independent network steering protocols based entirely on Gaussian operations -- which cannot be used for fully device-independent protocols, and thus become instead a viable option for minimal trust certification as soon as a single trusted input is inserted in the network. Our results present a basis for steering-based applications (such as randomness generation) with minimal trust beyond full nonlocality and with feasible experimental requirements.

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Shao-Hua Hu, Chung-Yun Hsieh, Huan-Yu Ku, Ray-Kuang Lee, Paolo Abiuso. 2026-06-24. Quantum steering in networks: Measurement-device-independent detection, continuous variables, and practical Gaussian schemes. https://arxiv.org/abs/2606.25690

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