The DARPA Quantum Network

Abstract

Harvard University has recently built and begun to operate the world's first Quantum Key Distribution network under DARPA sponsorship 1 . The DARPA Quantum Network became fully operational on October 23, 2003 in BBN's laboratories, and in June 2004 was fielded through dark fiber underneath the streets of Cambridge, Mass., to link our campuses with non-stop quantum cryptography, twenty-four hours per day. It is the world's first quantum cryptography network and indeed probably the first metro-area QKD deployment in continuous operation. As of December 2004, it consists of six QKD nodes. Four are used in BBN-built, interoperableweak-coherent QKD systems running at a 5 MHz pulse rate through telecommunications fiber, and inter-connected via a photonic switch. Two are NIST-built electronics for a high speed free-space QKD system. All run BBN's full suite of production-quality QKD protocols. In the near future, we plan to add four more quantum cryptographic nodes based on a variety of physical phenomena, and start testing the resulting network against sophisticated attacks.This chapter introduces the DARPA Quantum Network as it currently exists and briefly outlines our plans for the near future. We first describe the motivation for our work and define the basic principles of a quantum cryptographic network (which may be composed of a number of QKD systems with relays and/or photonic switches). We then discuss the specifics of our current weak-coherent QKD network, including its QKD links, photonic switches for "untrusted" networks, and key relay protocols for "trusted" networks. We conclude with future plans and our acknowledgements. Current Status of the DARPA Qua ntum NetworkFigure 1 displays a fiber diagram of the DARPA Quantum Network's buildout through Cambridge, Mass., as of December 2004. The network consists of two weakcoherent BB84 transmitters (Alice, Anna), two compatible receivers (Bob, Boris), and a 2x2 switch that can couple any transmitter to any receiver under program control. Alice, Bob, and the switch are in BBN's laboratory; Anna is at Harvard; and Boris is at Boston University. The fiber strands linking Alice, Bob, and the switch are several meters long. The Harvard-BBN strand is approximately 10 km. The BU-BBN strand is approximately 19 km. Thus the Harvard-BU path, through the switch at BBN, is approximately 29 km. All strands are standard SMF-28 telecommunications fiber. splices and perhaps detector upgrades should allow operation to BU with mean photon numbers of 0.5. The DARPA Quantum Network also contains Ali and Baba, the electronics subsystems for a high-speed freespace QKD system designed and built by the National Institute of Standards and Technology (NIST). Ali and Baba run the BBN QKD protocols, and are linked into the overall network by key relay between Ali and Alice. It further contains two new entanglement-based nodes named Alex and Bard, built jointly by BU and BBN, but these nodes are not yet fully operational.

Improving TLS Security By Quantum Cryptography

“…Since December 2002, the first network link has been up and steadily operational [8]. More detailed descriptions of DARPA Quantum network may be found in papers [13][14][15].…”

“…The DARPA Quantum Network was jointly developed by researchers at Boston University, Harvard University, and BBN Technologies in 2004 [13]. The goal of this point-to-point DARPA Quantum network is to exploit QKD technology for standard internet traffic.…”

Framework for Wireless Network Security Using Quantum Cryptography

“…BBN DARPA quantum network is an example of such network. Researchers at Boston, Harvard University, and BBN technologies jointly developed the DARPA Quantum Network in 2004 [14]. The main goal was point-to-point Quantum network that exploited QKD technology for end-to-end network security via high speed QKD.…”

On the transmission capacity of quantum networks

“…This claim has been substantiated in the demonstration of the SECOQC-and DARPA-Networks [2], [3]. Hence it is fair to assume that the topology of the network is fixed and that the individual key-generation rates on each link are known (cf.…”

“…[3] for examples). Moreover, following the so-far proposed architectures of relay devices in a quantum network (see [2], [3],and [20]), it is reasonable to consider a quantum network as a system of interconnected buffers, where the secret message is repeatedly decrypted and re-encrypted before forwarding it to the next hop. The key-buffers in each relay node are constantly refilled by QKD protocols running in the background 24/7 and endlessly generating key-material for later usage.…”