Abstract
A no-signalling channel transforming quantum systems in Alice's and Bob's local laboratories is compatible with two different causal structures: () Alice's output causally precedes Bob's input and () Bob's output causally precedes Alice's input. Here I prove that two no-signalling channels that are not perfectly distinguishable in any ordinary quantum circuit can become perfectly distinguishable through the quantum superposition of circuits with different causal structures.
- Received 23 September 2011
DOI:https://doi.org/10.1103/PhysRevA.86.040301
©2012 American Physical Society