Quantum Advantage: A Single Qubit's Experimental Edge in Classical Data Storage

We implement an experiment on a photonic quantum processor establishing efficacy of an elementary quantum system in classical information storage. The advantage is established by considering a class of simple bipartite games played with the communication resource qubit and classical bit (c-bit), respectively. Conventional wisdom, as articulated by the no-go theorems of Holevo and Frenkel-Weiner, suggests that such a quantum advantage is unattainable in scenarios wherein sender and receiver possess shared randomness or classical correlation between them. Notably, the advantage we report is demonstrated in a scenario where participating players lack any form of shared randomness. Our experiment involves the development of a variational triangular polarimeter, enabling the realization of positive operator value measurements crucial for establishing the targeted quantum advantage. In addition to demonstrating a robust communication advantage of a single qubit our experiment also opens avenues for immediate applications in near-term quantum technologies. Furthermore, it constitutes a semi-device-independent non-classicality certification scheme for the quantum encoding-decoding apparatus, underscoring the broader implications of our work beyond its immediate technological applications.