  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.
