Quantitative Quantum Soundness for Bipartite Compiled Bell Games via the Sequential NPA Hierarchy
The authors established quantitative bounds for compiled Bell games, which use cryptography instead of physical separation to test quantum nonlocality. They introduced a new mathematical tool, the sequential Navascués-Pironio-Acín (NPA) hierarchy, proving that any dishonest prover's score is provably close to the ideal quantum score when the hierarchy converges.