As far as I can tell:

• the paper doesn't prove anything we didn't already know, but rather confirms QM yet again
• the Economist article is as completely awful as the average piece of quantum journalism
• Wikipedia mentions Hardy but doesn't discuss his version of the paradox
• there isn't a negative number of photons present, but there would be if photons had individual trajectories, which this experiment therefore proves is not the case, but we already knew that

Gleefully downvoted.

This site is no place for mindless link propagation.