Towards Device-Independent Quantum Key Distribution with Photonic Devices

TL;DR

This paper evaluates the feasibility of device-independent quantum key distribution using photonic circuits, introducing new computational methods to assess noise resistance and security, paving the way for practical quantum communication.

Contribution

It introduces an efficient SDP hierarchy and finite-statistics analysis for assessing photonic DIQKD feasibility, demonstrating the circuit's robustness against noise.

Findings

Photonic circuit shows sufficient noise resistance for DIQKD implementation.

New SDP-based methods effectively bound von Neumann entropy in this context.

Finite-statistics analysis confirms experimental viability of the proposed setup.

Abstract

Quantum Key Distribution (QKD) protocols enable two distant parties to communicate with information-theoretically proven secrecy. However, these protocols are generally vulnerable to potential mismatches between the physical modeling and the implementation of their quantum operations, thereby opening opportunities for side channel attacks. Device-Independent (DI) QKD addresses this problem by reducing the degree of device modeling to a black-box setting. The stronger security obtained in this way comes at the cost of a reduced noise tolerance, rendering experimental demonstrations more challenging: so far, only one experiment based on trapped ions was able to successfully generate a secret key. Photonic platforms have however long been preferred for QKD thanks to their suitability to optical fiber transmission, high repetition rates, readily available hardware, and potential for circuit integration. In this work, we assess the feasibility of DIQKD on a photonic circuit recently identified by machine learning techniques. For this, we introduce an efficient converging hierarchy of semi-definite programs (SDP) to bound the conditional von Neumann entropy and develop a finite-statistics analysis that takes into account full outcome statistics. Our analysis shows that the proposed optical circuit is sufficiently resistant to noise to make an experimental realization realistic.