Vatshal Srivastav

Quantum key distribution (QKD) enables the exchange of cryptographic keys with information-theoretic security. However, real-world implementations of QKD are often limited by noise, losses, and imperfect devices. High-dimensional quantum systems offer a promising route to overcome these limitations, enabling denser information encoding and enhanced resilience to noise and loss compared to traditional qubit-based protocols. On the other hand, device-independent (DI) protocols can address all adversarial cases due to device imperfections; however, existing security proofs have not shown any advantage associated with higher dimensions. In this work, we present a robust high-dimensional one-sided DI-QKD (1sDI-QKD) protocol whose security is certified through violations of quantum steering inequalities. By relaxing assumptions on one of the parties while still leveraging high dimensions, this approach improves the practicality of the protocols over fully device-independent QKD, offering promising experimental implications. We investigate 1sDI-QKD utilizing high-dimensional entanglement systems based on Srivastav et al. [PhysRevX.12.041023] framework and show that reverse reconciliation leverages the inherent asymmetry of the steering scenario, resulting in significantly higher key rates in the asymptotic regime as we increase the dimensions. Furthermore, we analyze the protocol's robustness to depolarizing noise and detection inefficiencies. Our results demonstrate the enhanced noise robustness and loss tolerance of high-dimensional 1sDI-QKD. The next step will be to experimentally validate these advantages, establishing high-dimensional 1sDI-QKD as a strong candidate for secure quantum communication under realistic conditions.