Chip-based Quantum Key Distribution

TL;DR

This paper demonstrates GHz-clocked, chip-integrated quantum key distribution devices using telecom industry components, enabling scalable, high-performance secure communication compatible with existing networks.

Contribution

It introduces monolithically integrated InP transmitter and SiO_xN_y receiver chips capable of implementing multiple QKD protocols with low error rates.

Findings

Achieved GHz-clocked QKD operation with low error rates.

Successfully demonstrated BB84, COW, and DPS protocols on integrated chips.

Devices meet requirements for various levels of future QKD networks.

Abstract

Improvement in secure transmission of information is an urgent practical need for governments, corporations and individuals. Quantum key distribution (QKD) promises security based on the laws of physics and has rapidly grown from proof-of-concept to robust demonstrations and even deployment of commercial systems. Despite these advances, QKD has not been widely adopted, and practical large-scale deployment will likely require integrated chip-based devices for improved performance, miniaturisation and enhanced functionality, fully integrated into classical communication networks. Here we report low error rate, GHz clocked QKD operation of an InP transmitter chip and a SiO$_x$N$_y$ receiver chip --- monolithically integrated devices that use state-of-the-art components and manufacturing processes from the telecom industry. We use the reconfigurability of these devices to demonstrate three important QKD protocols --- BB84, Coherent One Way (COW) and Differential Phase Shift (DPS) --- with performance comparable to state-of-the-art. These devices, when combined with integrated single photon detectors, satisfy the requirements at each of the levels of future QKD networks --- from point-of-use through to backbone --- and open the way to operation in existing and emerging classical communication networks.