Preparation contextuality powers parity-oblivious multiplexing

TL;DR

This paper demonstrates that quantum contextuality enables superior performance in parity-oblivious multiplexing tasks, with experimental validation showing violations of noncontextuality bounds and implementation of quantum random access codes.

Contribution

It introduces a generalized noncontextuality inequality for operational theories and experimentally verifies quantum violations, demonstrating quantum advantage in specific information-processing tasks.

Findings

Quantum theory violates noncontextuality inequalities.

Experimental realization of 2-to-1 and 3-to-1 quantum random access codes.

Quantum performance surpasses classical limits in parity-oblivious multiplexing.

Abstract

In a noncontextual hidden variable model of quantum theory, hidden variables determine the outcomes of every measurement in a manner that is independent of how the measurement is implemented. Using a generalization of this notion to arbitrary operational theories and to preparation procedures, we demonstrate that a particular two-party information-processing task, "parity-oblivious multiplexing," is powered by contextuality in the sense that there is a limit to how well any theory described by a noncontextual hidden variable model can perform. This bound constitutes a "noncontextuality inequality" that is violated by quantum theory. We report an experimental violation of this inequality in good agreement with the quantum predictions. The experimental results also provide the first demonstration of 2-to-1 and 3-to-1 quantum random access codes. Consequently, our experimental results also demonstrate better-than-classical performance for this task. They also represent the first demonstration of 2-to-1 and 3-to-1 quantum random access codes.