Voltage-controlled optics of a quantum dot.
We show how the optical properties of a single semiconductor quantum dot can be controlled with a small dc voltage applied to a gate electrode. We find that the transmission spectrum of the neutral exciton exhibits two narrow lines with approximately 2 mueV linewidth. The splitting into two linearly polarized components arises through an exchange interaction within the exciton. The exchange interaction can be turned off by choosing a gate voltage where the dot is occupied with an additional electron. Saturation spectroscopy demonstrates that the neutral exciton behaves as a two-level system. Our experiments show that the remaining problem for manipulating excitonic quantum states in this system is spectral fluctuation on a mueV energy scale.
Högele
Alexander
A
Center for NanoScience, Department für Physik, Ludwig-Maximilians-Universität, Geschwister-Scholl-Platz 1, 80539 Munich, Germany.
Seidl
Stefan
S
Kroner
Martin
M
Karrai
Khaled
K
Warburton
Richard J
RJ
Gerardot
Brian D
BD
Petroff
Pierre M
PM