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Direct observation of acoustic phonon mediated relaxation between coupled exciton states in a single quantum dot molecule

T. Nakaoka·H. J. Krenner·E. C. Clark·M. Sabathil·M. Bichler·Y. Arakawa·G. Abstreiter·J. J. Finley
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Abstract

We probe acoustic phonon mediated relaxation between tunnel coupled exciton states in an individual quantum dot molecule in which the inter-dot quantum coupling and energy separation between exciton states is continuously tuned using static electric field. Time resolved and temperature dependent optical spectroscopy are used to probe inter-level relaxation around the point of maximum coupling. The radiative lifetimes of the coupled excitonic states can be tuned from ~2 ns to ~10 ns as the spatially direct and indirect character of the wavefunction is varied by detuning from resonance. Acoustic phonon mediated inter-level relaxation is shown to proceed over timescales comparable to the direct exciton radiative lifetime, indicative of a relaxation bottleneck for level spacings in the range $ΔE\$ ~3-6 meV.

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T. Nakaoka, H. J. Krenner, E. C. Clark, M. Sabathil, M. Bichler, Y. Arakawa, G. Abstreiter, J. J. Finley. 2006-07-03. Direct observation of acoustic phonon mediated relaxation between coupled exciton states in a single quantum dot molecule. https://doi.org/10.1103/physrevb.74.121305

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