[MOS] April 8, 2008

[Zina Queen]

Seminar on
Modern Optics and Spectroscopy


Katherine Stone,
MIT

Multi-excitonic coupling in semiconductor nanostructures studied by 
multidimensional electronic Fourier transform spectroscopy

APRIL 8, 2008

12:00 - 1:00 p.m.
Grier Room 34-401


Ultrafast excitation of solids creates coherent superpositions of 
correlated many-particle states. For electronic excitations, 
important high-order many-body correlations may contribute strongly 
to signals measured in nonlinear spectroscopy, but often the 
contributions are highly convolved with those from lower-order 
correlations. These high-order correlations are often involved in 
coherent control schemes for quantum information processing, 
accessing exciton spin coherence and controlling electromagnetically 
induced transparency in semiconductors. Two-dimensional Fourier 
Transform spectroscopy has revealed vibrational or electronic 
coupling in a variety of condensed phase systems. In order to isolate 
the high-order correlations in nonlinear signals from semiconductor 
quantum wells we employ a Two-quantum 2D electronic FTS technique 
that is based on spatiotemporal pulse shaping. This is the optical 
analogue of multiple-quantum techniques used routinely in 2D NMR 
spectroscopy. We are able to isolate and record direct observations 
of the many-body dynamics in a condensed phase system that are beyond 
a mean-field approximation
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