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           COLLOQUIUM OF THE COMPUTATIONAL MATERIALS SCIENCE CENTER
                              College of Science
                       (CDS Department CSI 898-Sec 001)
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       Quantum Geometrical Operations on Rare-Earth Ensemble

                              Ming Tian
Department of Physics and Astronomy, George Mason University, Fairfax, VA

It has been proposed and demonstrated that rare earth ion ensembles doped 
in inorganic crystals can be used as quantum information carrier in quantum 
computation and quantum memory. Rare-earth-based system has the advantages 
of the solid-state system with its quantum state fully controlled through 
laser induced electronic transitions. Complete control of the qubit state 
can be realized through the quantum state evolution of geometrical phase 
change. Compared with conventional dynamical quantum gates the geometrical 
operations have the potential of being resilient to certain noise on the 
driving laser pulses that cause local disturbance on the evolution path. 

In this talk, the experimental demonstration of the geometrical quantum 
operations that manipulate the quantum state of thulium ion ensemble in 
two dimensional Hilbert space will be reported. The complete control of 
Bloch vector on the Bloch sphere were demonstrated through geometrical 
paths driven by composite laser pulse sequences. The results of the 
operations were measured as the phase and the amplitude changes on 
photon echoes. The fidelity of the operations was analyzed against the 
non-ideal laser pulses and compared with the dynamical operations driven 
by single laser pulse. The results confirm the high fidelity of the 
geometrical operations under realistic conditions.

                        Monday, February 25, 2008
                                  4:30 pm
                     Room 301, Research I, Fairfax Campus

Refreshments will be served at 4:15 PM.
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Find the schedule at www.cmasc.gmu.edu/seminar/schedule.html
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