Bell test experiments

Bell state

Quantum entanglement

Physics

Bell's theorem

Pathology

Mathematics

Statistical physics

Statistics

Randomness

CHSH inequality

Quantum nonlocality

Philosophy

Alternative medicine

Locality

Theoretical physics

Protocol (science)

Computer science

Linguistics

Quantum mechanics

Local hidden variable theory

Medicine

Quantum

npj Quantum Information

Bell non-locality plays a fundamental role in quantum theory. Numerous tests of the Bell inequality have been reported as the ground-breaking discovery of the Bell theorem. Up to now, however, most discussions of the Bell scenario have focused on a single pair of entangled particles distributed to only two separated observers. Recently, it has been shown surprisingly that multiple observers can share the non-locality from an entangled pair using the method of weak measurement without post-selection [Phys. Rev. Lett. 114 , 250401 (2015)]. Here we report an observation of double CHSH-Bell inequality violations for a single pair of entangled photons with strength continuous-tunable optimal weak measurement in a photonic system. Our results shed new light on the interplay between non-locality and quantum measurements and our design of weak measurement protocol may also be significant for important applications such as unbounded randomness certification and quantum steering.

Observation of non-locality sharing among three observers with one entangled pair via optimal weak measurement