Coherent Optical Spectroscopy of a Strongly Driven Quantum Dot
Xiaodong Xu,1
Bo Sun,1
Paul R. Berman,1
Duncan G. Steel,1*
Allan S. Bracker,2
Dan Gammon,2
L. J. Sham3
Quantum dots are typically formed from large groupings of atoms
and thus may be expected to have appreciable many-body behavior
under intense optical excitation. Nonetheless, they are known
to exhibit discrete energy levels due to quantum confinement
effects. We show that, like single-atom or single-molecule two-
and three-level quantum systems, single semiconductor quantum
dots can also exhibit interference phenomena when driven simultaneously
by two optical fields. Probe absorption spectra are obtained
that exhibit Autler-Townes splitting when the optical fields
drive coupled transitions and complex Mollow-related structure,
including gain without population inversion, when they drive
the same transition. Our results open the way for the demonstration
of numerous quantum level–based applications, such as
quantum dot lasers, optical modulators, and quantum logic devices.
2 The Naval Research Laboratory, Washington, DC 20375, USA.
3 Department of Physics, University of California–San Diego, La Jolla, CA 92093, USA.
* To whom correspondence should be addressed. E-mail: dst{at}umich.edu
