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     COLLOQUIUM OF THE COMPUTATIONAL MATERIALS SCIENCE CENTER
AND THE SCHOOL OF PHYSICS, ASTRONOMY, & COMPUTATIONAL SCIENCES
               (CSI 898-Sec 001 crosslisted with PHYS 703)
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       Nuclear spins in quantum dots: obstacle or opportunity?

                       Sophia Economou
             Electronics Science and Technology Division
              Naval Research Laboratory, Washington DC

Carrier spins in low dimensional semiconductor structures comprise a major
research field with potential applications in spin-based electronics
(spintronics) and quantum information. In quantum dots, the main source of
loss of electron spin coherence is the bath of nuclear spins in the host
material, leading to the view that nuclear spins are a nuisance in these
systems. On the other hand, polarizing the nuclear spins can not only mitigate
this effect but also produces an effective magnetic field that is used
experimentally to implement coherent spin rotations. Moreover, due to the long
coherence time of the nuclear spins, there exists the tantalizing possibility
that the nuclear spin ensemble could be harnessed as a long-lived quantum
memory.  The key to unlocking this potential resource is to understand the
dynamic creation of nuclear spin polarization through the carrier (electron or
hole) spin and the complex multi-spin dynamics that span orders of magnitude
in timescales in these systems. 

I will present experimental results that reveal intriguing physics in 
these systems and I will highlight our theoretical efforts in laying the 
foundations of a systematic, microscopic theory of dynamic nuclear 
polarization.

                          March 24, 2014
                               4:30 pm
                    Room 3301, Exploratory Hall, Fairfax Campus

Refreshments will be served at 4:15 PM.
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Find the schedule at http://www.cmasc.gmu.edu/seminars.htm