>VITAE:
Jonathan P. Dowling is group supervisor
at the Jet Propulsion Laboratory of Pasadena, is expert of theoretical
quantum optics, quantum information theory, laser physics, and mathematical
physics. He worked for Army Aviation & Missile Command from 1990 through
1998, serving on numerous Department of Defense Review Boards and Organizational
Committees, for the Army Research Office (ARO),
the Defense Advanced Projects Research Agency (DARPA), and the National
Security Agency (NSA), on topics such as Photonic BandGap Materials,
Quantu Cryptography and Computing, The Atom Laser, Information Technology,
Atomic, Molecular, and Optical Physics and General Relativity. In particular
he made relevant studies on Relativistic Effects in the Global Positioning
System.



It has been know for some time  see Kimble  that strong
optical nonlinearities, such as those generated in cavity QED, are sufficient
for making the photonphoton interactions required for scalable photonic
quantum computing. Recent work of Knill, LaFlamme, and Milburn (KLM), shows
us that scalable quantum computing with photons may also be had by exploiting
only linear optics and projective measurements, but no explicit nonlinearities.
The question naturally arises, “In what way are projective measurements
like optical nonlinearities?” I will discuss a general scheme by which
we may take an arbitrary projective measurement protocol and from it extract
the equivalent set up with effective optical nonlinearities. I will also
discuss applications of such schemes to quantum information processing devices,
such as repeaters, as well as to optical quantum metrology. 