Researchers have explored the limits of non-signaling (NS) assistance in prepare-and-measure (PM) scenarios with classical communication, considering both adaptive and non-adaptive protocols. These scenarios are fundamental to understanding how non-local correlations can enhance communication, and the study aims to go beyond the capabilities of quantum theory.

The work provides simple characterizations for the sets of behaviors achievable with both adaptive and non-adaptive NS assistance in arbitrary PM scenarios. A key finding is that non-adaptive NS assistance is already strong enough to reproduce quantum communication with the same message dimension: a qudit can be simulated by a classical dit non-adaptively assisted by NS correlations.

When comparing adaptive and non-adaptive NS assistance, the authors prove that any adaptive NS advantage can be traced back to scenarios where the receiver has no measurement choice. This rules out the genuinely multi-setting advantages found in entanglement-assisted quantum protocols. Finally, the study identifies all PM scenarios where adaptive NS strategies provide a strict advantage over non-adaptive ones.