1109.5154 (G. Chiribella)

Perfect discrimination of no-signalling channels via quantum
superposition of causal structures    [PDF]

G. Chiribella

A no-signalling channel transforming quantum systems in Alice's and Bob's laboratories is com- patible with two different causal structures: (A < B) Alice's output causally precedes Bob's input and (B< A) Bob's output causally precedes Alice's input. I show that a quantum superposition of circuits operating within these two causal structures enables the perfect discrimination between no-signalling channels that can not be perfectly distinguished by any ordinary circuit.

View original: http://arxiv.org/abs/1109.5154