Current status of the DARPA Quantum Network

TL;DR

The paper describes the development, current operational status, and technological diversity of the DARPA Quantum Network, the world's first metropolitan quantum cryptography network, highlighting its hardware, software, and ongoing expansion efforts.

Contribution

It provides a comprehensive update on the deployment, hardware, and operational experience of the first large-scale quantum cryptography network in a metropolitan area.

Findings

Network has 6 operational nodes since 2004

Supports multiple QKD technologies including fiber and free-space

Expansion to 10 nodes is underway

Abstract

This paper reports the current status of the DARPA Quantum Network, which became fully operational in BBN's laboratory in October 2003, and has been continuously running in 6 nodes operating through telecommunications fiber between Harvard University, Boston University, and BBN since June 2004. The DARPA Quantum Network is the world's first quantum cryptography network, and perhaps also the first QKD systems providing continuous operation across a metropolitan area. Four more nodes are now being added to bring the total to 10 QKD nodes. This network supports a variety of QKD technologies, including phase-modulated lasers through fiber, entanglement through fiber, and freespace QKD. We provide a basic introduction and rational for this network, discuss the February 2005 status of the various QKD hardware suites and software systems in the network, and describe our operational experience with the DARPA Quantum Network to date. We conclude with a discussion of our ongoing work.