I recall reading a paper that discussed a hypothetical pair black boxes that could violate Bell inequalities better than what's achievable with quantum mechanics.

For example, suppose Alice and Bob are trying to win the (Alice_choice XOR Bob_choice) = (referee_choice_A AND referee_choise_B) game (the CHSH game). Classically the best strategy wins 75% of the time. Quantumly the best strategy wins ~85% of the time. But these hypothetical boxes would win 100% of the time, and the paper talked about what you could do (and not do) with something like that.

I want to reference the paper, but I can't find it!

closed as off-topic by Alexander S King, James Kingsbery, Conifold, user19563, Keelan May 3 '16 at 8:45

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    Welcome to the philosophy SE. This question seems more appropriate for the physics SE. – Alexander S King May 2 '16 at 17:15
  • "Better than what's achievable with quantum mechanics" sounds like better than what's physically achievable. And I agree with Alexander. – Conifold May 2 '16 at 18:45
  • @Conifold Yes, it's better than what's physically achievable. The paper is about hypothetical boxes, which is why I thought it was philosophy. – Craig Gidney May 2 '16 at 18:50
  • That's a fair point, but the use of a hypothetical seems to be aimed at fleshing out physics rather than philosophy, as the Maxwell demon is used to flesh out the relation between kinetic theory and thermodynamics. – Conifold May 3 '16 at 17:30

The paper was 'On the power of non-local boxes' by A. Broadbent, A. A. Methot. It's a theoretical computer science paper, which is part of the reason I had trouble finding it:

A non-local box is a virtual device that has the following property: given that Alice inputs a bit at her end of the device and that Bob does likewise, it produces two bits, one at Alice's end and one at Bob's, such that the XOR of the outputs is equal to the AND of the inputs. [...] given that a maximally entangled pair of qubits is non-local, why is it not maximally non-local? [...] we show that the non-local box can simulate quantum correlations that no entangled pair of qubits can in a bipartite scenario and even in a multi-party scenario. [...] we show quantum correlations whose simulation requires an exponential amount of non-local boxes, in the number of maximally entangled qubit pairs.

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