March 11, 2009
3 pm in Howey Physics Room N110

Georgia Tech Quantum Institute Colloquium

Poul Jessen
College of Optical Sciences, University of Arizona

"Quantum Control of Cold Atom Ground States"

 

Laboratory techniques to manipulate and observe ultracold atoms make these an attractive platform for testing new ideas in quantum control and measurement. I will review a series of experiments in which we have used tensor AC Stark shifts and magnetic fields to drive non-trivial quantum dynamics of a large spin-angular momentum associated with an atomic hyperfine ground state. The nonlinear spin Hamiltonian is sufficiently general to achieve universal quantum control over the 2F+1 dimensional state space, and allows us to generate arbitrary spin states and perform a full quantum state reconstruction of the result.  Most recently we have used these control and measurement tools to realize a common paradigm for quantum chaos known as the quantum kicked top.  Observing the dynamics of this system directly in quantum phase space has given an unprecedented look at quantum/classical correspondence. We are now implementing a new scheme for quantum control of the entire ground hyperfine manifold, based solely on interaction with DC, radiofrequency and microwave magnetic fields.  The longer coherence times available with this approach will allow us to explore new ideas related to robust control and constructive design of unitary transformations.