If You Were This Computer, You'd Already Have Read This

I like to think that I'm a pretty smart guy. Many people have even told me that I'm as "smart as s" whoever that is. Anyway, what the fudge is going on at the Univ. of Illinois at Urbana-Champaign? I used to think I had some modicum of understanding of Quantum Mechanics but "counterfactual computation"? Here, you read it:

"By placing our photon in a quantum superposition of running and not running the search algorithm, we obtained information about the answer even when the photon did not run the search algorithm," said graduate student Onur Hosten, lead author of the Nature paper. "“We also showed theoretically how to obtain the answer without ever running the algorithm, by using a '‘chained Zeno' effect."

Through clever use of beam splitters and both constructive and destructive interference, the researchers can put each photon in a superposition of taking two paths. Although a photon can occupy multiple places simultaneously, it can only make an actual appearance at one location. Its presence defines its path, and that can, in a very strange way, negate the need for the search algorithm to run.