Regensburg 2004 – wissenschaftliches Programm
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HL: Halbleiterphysik
HL 50: Quantenpunkte und -dr
ähte: Optische Eigenschaften III
HL 50.8: Vortrag
Freitag, 12. März 2004, 12:45–13:00, H14
Femtosecond nonlinear spectroscopy of two quantum dots coupled by dipole-dipole interaction — •Kerstin Müller1, Thomas Unold1, Christoph Lienau1, Thomas Elsaesser1, and Andreas D. Wieck2 — 1Max-Born-Institut für Nichtlineare Optik und Kurzzeitspektroskopie, 12489 Berlin — 2Ruhr-Universität Bochum, D-44870 Bochum
The transient optical nonlinearities of single semiconductor quantum dots (QDs) are intensely investigated as QDs receive attention for implementations of quantum logic. For realizing potentially scalable quantum gates it is essential to demonstrate coherent interactions between different quantum dots, e.g. via dipole-dipole coupling[1]. Here, we report the first study of the transient optical nonlinearities of two coupled interface quantum dots. With a 2-ps pump laser, we excite the excitonic resonance of a first QD (QD 1) and monitor the pump-induced biexcitonic nonlinearity of this QD with an ultrafast probe laser in a near-field spectrometer[2]. Varying the intensity of the pump laser, pronounced Rabi oscillations are observed. We simultaneously monitor also the excitonic nonlinearities of one neighboring QD within the 200 nm spot size of the near-field experiment. We find a clear pump-induced spectral shift of the exciton resonance of QD 2 due to the dipole-dipole interaction between both QDs. The observation of Rabi oscillations on the second quantum dot after resonant excitation of QD 1 unambiguously establishes dipole-dipole coupling between two individual quantum dots.
[1] E. Biolatti et al., Phys. Rev. Lett. 85, 5647 (2000).
[2] T. Guenther et al., Phys. Rev. Lett. 89 057401 (2002).