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arXiv · 2003.02980

Spectral broadening of optical transitions at tunneling resonances in InAs/GaAs coupled quantum dot pairs

P. Kumar·C. Jennings·M. Scheibner·A. S. Bracker·S. G. Carter·D. Gammon
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Abstract

We report on linewidth analysis of optical transitions in InAs/GaAs coupled quantum dots as a function of bias voltage, temperature, and tunnel coupling strength. A significant line broadening up to 100 $μ$eV is observed at hole tunneling resonances where the coherent tunnel coupling between spatially direct and indirect exciton states is maximized, corresponding to a phonon-assisted transition rate of 150 ns${}^{-1}$ at 20 K. With increasing temperature, the linewidth shows broadening characteristic of single-phonon transitions. The linewidth as a function of tunnel coupling strength tracks the theoretical prediction of linewidth broadening due to phonon-assisted transitions, and is maximized with an energy splitting between the two exciton branches of 0.8$-$0.9 meV. This report highlights the linewidth broadening mechanisms and fundamental aspects of the interaction between these systems and the local environment.

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P. Kumar, C. Jennings, M. Scheibner, A. S. Bracker, S. G. Carter, D. Gammon. 2020-08-12. Spectral broadening of optical transitions at tunneling resonances in InAs/GaAs coupled quantum dot pairs. https://doi.org/10.1103/physrevb.102.085423

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