Demonstrating the power of quantum computers, certification of highly
  entangled measurements and scalable quantum nonlocality
Increasingly sophisticated quantum computers motivate the exploration of
their abilities in certifying genuine quantum phenomena. Here, we demonstrate
the power of state-of-the-art IBM quantum computers in correlation experiments
inspired by quantum networks. Our experiments feature up to 12 qubits and
require the implementation of paradigmatic Bell-State Measurements for scalable
entanglement-swapping. First, we demonstrate quantum correlations that defy
classical models in up to nine-qubit systems while only assuming that the
quantum computer operates on qubits. Harvesting these quantum advantages, we
are able to certify 82 basis elements as entangled in a 512-outcome
measurement. Then, we relax the qubit assumption and consider quantum
nonlocality in a scenario with multiple independent entangled states arranged
in a star configuration. We report quantum violations of source-independent
Bell inequalities for up to ten qubits. Our results demonstrate the ability of
quantum computers to outperform classical limitations and certify scalable
entangled measurements.
Elisa Bäumer Nicolas Gisin Armin Tavakoli