<!doctype html public "-//W3C//DTD W3 HTML//EN">
<html><head><style type="text/css"><!--
blockquote, dl, ul, ol, li { padding-top: 0 ; padding-bottom: 0 }
--></style><title>April 8, 2008</title></head><body>
<div><font face="Arial" color="#000000">Seminar on<br>
<b>Modern Optics and Spectroscopy<br>
<br>
<br>
Katherine Stone</b>,<br>
MIT<br>
<br>
<i><b>Multi-excitonic coupling in semiconductor nanostructures studied
by multidimensional electronic Fourier transform spectroscopy<br>
<br>
</b></i>APRIL 8, 2008</font><br>
<font face="Arial" color="#000000"></font></div>
<div><font face="Arial" color="#000000">12:00 - 1:00 p.m.</font></div>
<div><font face="Arial" color="#000000">Grier Room 34-401</font></div>
<div><font face="Arial" color="#000000"><br></font></div>
<div><font face="Arial" color="#000000"><br>
</font><font face="Times New Roman" color="#000000">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</font></div>
</body>
</html>