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.