Posted By: AngusThat's a good reason to abandon causality.

In “the most beautiful experiment” done so far, according to Rubino, Jian-Wei Pan at the University of Science and Technology of China in Hefei demonstrated in 2019 that two parties can compare long strings of bits exponentially more efficiently when transmitting bits in both directions at once rather than in a fixed causal order — an advantage proposed by Brukner and co-authors in 2016.

A different group in Hefei reported in January that, whereas engines normally need a hot and cold reservoir to work, with a quantum switch they could extract heat from reservoirs of equal temperature — a surprising use suggested a year ago by Oxford theorists.