Quantum Information Science (QIS) Seminar

(CSI 991 - 006)

Monday, October 03, 2005, 4:30 - 6:00 PM
                                                           George Mason University, Fairfax Campus
                                                 Science Showcase, George Johnson Center, Room 237

Presenter: Phil Johnson, U.S. Army Research Laboratory

Title: Quantum Repeaters for a Global Communication Network

Abstract: It is possible to quantum teleport information with (in principle) complete security from interception or eavesdropping.  In 1997, photon states were quantum teleported a few meters, and in 2004 this distance was increased to 600 meters across the Danube River in Vienna.  Over roughly the same period of time, a number of short-distance quantum communication links, using single photons but not teleportation, have been implemented, including a 760 meter high-speed testbed at NIST moving 1MB of quantum encrypted bits a second.  It should be possible to expand such (non-teleporting) systems to small networks over metropolitan-scale distances, but the attenuation of photons with distance probably limits the maximum achievable distances to a few hundred kilometers.  A true global quantum network requires quantum repeaters, which will allow the teleportation of data across the globe.  I will talk about why teleportation and quantum repeaters are needed for true scalability and long-distances, how quantum repeaters work, and what it will take to build them.

About the Author: Dr. Philip Johnson came to the National Institute of Science and Technology in Gaithersburg, Maryland in 2004 as a National Research Council postdoctoral fellow.  He is a theorist working on a variety of new quantum technologies, including quantum repeaters, quantum computing with neutral atoms in optical lattices, superconducting qubits, and entanglement-based sensors and probes.  He also does basic research in a number of areas including the fields of quantum information theory, Bose-Einstein condensation, and ultra-cold atoms.  Dr. Johnson received a Ph.D. in theoretical physics from the University of Maryland in 2000 working on general relativity and quantum field theory.  He was at Maryland until 2004 as a postdoctoral research associate with the superconducting quantum computing group, where he helped design some of the first coupled superconducting qubit devices.