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

Abstract

A no-signalling channel transforming quantum systems in Alice's and Bob's laboratories is compatible 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.

5 + 5 pages, published version

References in corpus (4)

• Quantum Illumination with Gaussian States
• Quantum correlations with no causal order
• Quantum Circuits Architecture
• No-signaling, entanglement-breaking, and localizability in bipartite channels

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