Hardy's Non-locality Paradox and Possibilistic Conditions for Non-locality

Understand

Hardy's non-locality paradox is a proof without inequalities showing that certain non-local correlations violate local realism.

• It is `possibilistic' in the sense that one only distinguishes between possible outcomes (positive probability) and impossible outcomes (zero probability).
• Here we show that Hardy's paradox is quite universal: in any (2,2,l) or (2,k,2) Bell scenario, the occurence of Hardy's paradox is a necessary and sufficient condition for possibilistic non-locality.
• In particular, it subsumes all ladder paradoxes.