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Abstract

All quantum scientists are aware of quantum non-locality, and indeed its existence is the source of security for QKD. However, it has never been shown in the laboratory to the satisfaction of the skeptics.
I will talk here about a few notions of quantum non-locality: quantum steering (or EPR-steering), the Bell test, and the idea of a spectrum of device-independence in QKD. I will also detail the various loopholes that the skeptics present, and how they have been approached and conquered over the years, until today we stand within sight of a “final” proof: the “loophole-free” Bell test.
I will also briefly discuss some of the technical details—both theoretical and experimental—that make such loophole-free results difficult to achieve, and how I and others have tried to overcome them.

References:
DH Smith, G Gillett et al., Conclusive quantum steering with superconducting transition-edge sensors. Nat. Commun. 3:625 (2012)
DH Smith. High-efficiency quantum photonics. PhD Thesis, University of Queensland (2013)
BG Christensen et al., Detection-loophole-free test of quantum nonlocality, and applications. Phys Rev Lett, 111:130406 (2013)