The following submission statement was provided by /u/Woke_Soul:

In simple terms, instead of extracting something from nothing, the energy was "borrowed" from somewhere else, taking advantage of the idea of quantum entanglement, the fact that two subatomic particles can change their state in line with the other, even when the two are separated by a distance.

Please reply to OP's comment here: https://old.reddit.com/r/Futurology/comments/11n1wwy/researchers_say_they_managed_to_pull_quantum/jbkxp6x/