<title>Current status of the DARPA quantum network (Invited Paper)</title>

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.Detailed descriptions and rationale for this approach may be found in earlier papers 1,2,3 . 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 ongoing work.

The SECOQC quantum key distribution network in Vienna

“…As pointed out above, QKD links (pairs of QKD devices associated by a quantum and a classical communication channel which perform QKD protocol and realize QKD key 23 agreement between the parties controlling the devices) can only operate over point-to-point connections between two users, and cannot be deployed over any arbitrary network topology. To overcome those limitations, it is important to realize networking of QKD links or QKD networks between multiple users.…”

“…The particular mechanism (sometimes called hop-by-hop) works as follows (see e.g. [29] or [23]). The nodes are equipped with classical memories accumulating the QKD key material generated over the connected QKD links.…”

“…The natural idea to extend point-to-point connections to networks has been studied in the QKD case theoretically [19] and experimentally [20,21]. In parallel to the conception of SECOQC a first proof-of-principle QKD network demonstrator, the 'DARPA Quantum Network', was deployed between Harvard University, Boston University and BBN in 2004 [22,23].…”

Using quantum key distribution for cryptographic purposes: A survey

“…It provides a practical solution adopted within the BBN Darpa Quantum Network project [76]. Such a composition provides a practical solution to realise a point-to-point VPN encryptor, that can be deployed in layer 2 (link) in the OSI network layer model [6] or directly in the layer 3 (network), for example by interfacing QKD-based key exchange with IPSEC [77,78].…”

“…Active optical switching can also be used to allow the selective connection of any two QKD nodes with a direct quantum channel. The BBN Darpa quantum network [76,77] contains an active 2-by-2 optical switch in one node, that can be used to actively switch between two network topologies. Optical functions can thus be used to realise multi-user QKD and the corresponding nodes do not need to be trusted, since quantum signals are transmitted over a quantum channel with no interruption from one enduser QKD device to the other one.…”