Noise-Resilient Quantum Random Access Codes

TL;DR

This paper introduces a practical noise-tolerance technique for quantum random access codes, demonstrating its effectiveness through a photonic implementation that revives quantum advantage under noisy conditions.

Contribution

The authors propose a novel method to enable noise resilience in QRACs, allowing quantum advantage to be maintained or recovered in noisy environments, supported by experimental photonic results.

Findings

Noise-tolerance technique successfully recovers quantum advantage in QRACs

Experimental implementation with polarization-encoded qubits shows revival of quantum advantage under noise

Violation of a dimension witness confirms the effectiveness of the noise-resilience method

Abstract

A $n^d \xrightarrow{p} 1$ Quantum Random Access Code (QRAC) is a communication task where Alice encodes $n$ classical bits into quantum states of dimension $d$ and transmits them to Bob, who performs appropriate measurements to recover the required bit with probability $p$. In the presence of a noisy environment, the performance of a QRAC is degraded, losing the advantage over classical strategies. We propose a practical technique that enables noise tolerance in such scenarios, recovering the quantum advantage in retrieving the required bit. We perform a photonic implementation of a $2^2 \xrightarrow {\text{p}} 1$ QRAC using polarization-encoded qubits under an amplitude-damping channel, where simple operations allow for noise robustness showing the revival of the quantum advantage when the noisy channel degrades the performance of the QRAC. This revival can be observed by violating a suitable dimension witness, which is closely related to the average success probability of the QRAC. This technique can be extended to other applications in the so-called prepare-and-measure scenario, enhancing the semi-device-independent protocol implementations.