Device-Independent Quantum Key Distribution beyond qubits

TL;DR

This paper investigates the advantages and limitations of using higher-dimensional quantum systems, like qutrits, in device-independent quantum key distribution, analyzing their noise resilience and key rate bounds.

Contribution

It provides a comparative analysis of qubits and qutrits in DIQKD, including new bounds and insights into noise thresholds for high-dimensional systems.

Findings

Higher-dimensional systems can potentially improve noise thresholds.

Numerical bounds suggest increased dimensions may enhance key rates.

Experimental complexity rises with system dimension.

Abstract

Device-Independent Quantum Key Distribution (DIQKD) aims to generate secret keys between two parties without relying on trust in their employed devices, imposing strict noise constraints for key generation. This study explores the resilience of high-dimensional quantum systems in DIQKD, focusing on a comparison between qubits and qutrits. Lower bounds on achievable key rates are investigated through numerical optimization, while upper bounds are evaluated using the Convex-Combination attack, which has been further extended to account for arbitrary dimensions. The observed difference between these bounds provides insights into noise thresholds and potential enhancements in DIQKD scenarios, prompting debate on the merit of increased dimensions given the associated experimental efforts required.