Physics and Astronomy Colloquium
		   Tuesday, January 15, 2002
	4:10 p.m., Room 118 Physics-Astronomy Building
     Refreshments served at 3:45 p.m. outside Room 224 PA

	    "Trapped" Photons and Quantum Information
 
          		 Mikhail Lukin
 
       		       Physics Department
       		       Harvard University
 
 
We discuss quantum optical techniques that allow for an accurate
manipulation of quantum information using  collective excitations in
atomic systems.
 
In particular, we describe a fast and robust mechanism for quantum state
transfer  between light fields and atoms. This is achieved
by adiabatically reducing the group velocity of  propagating light to
zero, thereby ``trapping'' the photon states in atomic ensembles.
We describe the basic principles of this technique as well
as our recent experimental progress towards realization of these ideas.
 
We next outline possible mechanisms for manipulating collective quantum
states  in atomic ensembles and describe how these techniques
can be used to implement important protocols in quantum information
processing. As two specific examples,  the ideas based on optical
manipulation of mesoscopic ensembles of cold atoms will be discussed
and a scalable technique that allows to implement robust quantum
communication over long, lossy optical channels will be outlined.