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upstart writes in with an IRC submission:

Major quantum computational breakthrough is shaking up physics and maths:

MIP* = RE is not a typo. It is a groundbreaking discovery and the catchy title of a recent paper in the field of quantum complexity theory. Complexity theory is a zoo of "complexity classes" – collections of computational problems – of which MIP* and RE are but two.

The 165-page paper shows that these two classes are the same. That may seem like an insignificant detail in an abstract theory without any real-world application. But physicists and mathematicians are flocking to visit the zoo, even though they probably don't understand it all. Because it turns out the discovery has astonishing consequences for their own disciplines.

[...] RE stands for problems that can be solved by a computer. It is the zoo. Let's have a look at some subclasses.

[...] Allowing the provers of MIP to share an entangled qubit leads to the class MIP*.

It seems obvious that communication between the provers can only serve to help the provers coordinate lies rather than assist the interrogator in discovering truth. For that reason, nobody expected that allowing more communication would make computational problems more reliable and solvable. Surprisingly, we now know that MIP* = RE. This means that quantum communication behaves wildly differently to normal communication.

IP = Interactive Polynomial time solvable using an interactive proof.
MIP = Multiple Interactive Provers that are not allowed to communicate between each other.
RE = Recursively Enumerable.

[Edited to add a definition for RE and to correct the definition of IP. - Ed]

Original Submission