  The distribution and verification of quantum nonlocality across a network of
users is essential for future quantum information science and technology
applications. However, beyond simple point-to-point protocols, existing methods
struggle with increasingly complex state preparation for a growing number of
parties. Here, we show that, surprisingly, multiparty loophole-free quantum
steering, where one party simultaneously steers arbitrarily many spatially
separate parties, is achievable by constructing a quantum network from a set of
qubits of which only one pair is entangled. Using these insights, we
experimentally demonstrate this type of steering between three parties with the
detection loophole closed. With its modest and fixed entanglement requirements,
this work introduces a scalable approach to rigorously verify quantum
nonlocality across multiple parties, thus providing a practical tool towards
developing the future quantum internet.
