Just How Coordinated is Nature’s Quantum Entanglement?

The answer is probably a bit more complicated, but similar to asking, just how many licks does it take to get to the center of a Tootsie Pop? “The world may never know…” Because Quantum is Coming. Qubit.

**How ‘spooky’ is quantum physics? The answer could be incalculable**

In brief…

+ Albert Einstein famously said that quantum mechanics should allow two objects to affect each other’s behaviour instantly across vast distances, something he dubbed “spooky action at a distance”1. Decades after his death, experiments confirmed this, but to this day, it remains unclear exactly how much coordination nature allows between distant objects. Now, five researchers say they have solved a theoretical problem that shows that the answer is, in principle, unknowable.

*If their proof holds up, “it’s a super-beautiful result” says Stephanie Wehner, a theoretical quantum physicist at Delft University of Technology in the Netherlands.*

+ The theorem concerns a game-theory problem, with a team of two players who are able to coordinate their actions through quantum entanglement, even though they are not allowed to talk to each other. This enables both players to ‘win’ much more often than they would without quantum entanglement. But it is intrinsically impossible for the two players to calculate an optimal strategy, the authors show. This implies that it is impossible to calculate how much coordination they could theoretically reach. “There is no algorithm that is going to tell you what is the maximal violation you can get in quantum mechanics,” says co-author Thomas Vidick of the California Institute of Technology in Pasadena.

+ Quantum entanglement is at the heart of the nascent fields of quantum computing and quantum communications, and could be used to make super-secure networks. In particular, measuring the amount of correlation between entangled objects across a communication system can provide proof that it is safe from eavesdropping. But the results probably do not have technological implications, Wehner says, because all applications use quantum systems which are ‘finite’. In fact, it could be difficult to even conceive an experiment that could test quantum weirdness on an intrinsically ‘infinite’ system, she says. *Read More…*

Source:* nature. Davide Castelvecchi, How ‘spooky’ is quantum physics? The answer could be incalculable… *

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