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Coherent coupling between exciton resonances governed by the disorder potential

2013; American Physical Society; Volume: 88; Issue: 7 Linguagem: Inglês

10.1103/physrevb.88.075316

1550-235X

Yuri D. Glinka, Zheng Sun, Mikhail Erementchouk, Michael N. Leuenberger, Alan D. Bristow, Steven T. Cundiff, Allan S. Bracker, Xiaoqin Li,

Photochemistry and Electron Transfer Studies

Monolayer fluctuations in the thickness of a semiconductor quantum well (QW) lead to the formation of spectrally resolved excitons located in the narrower, average, and thicker regions of the QW. Whether or not these excitons are coherently coupled via Coulomb interaction is a long-standing debate. We demonstrate that different types of disorder potential govern coherent coupling among excitons, and the coupling strength can be quantitatively measured using optical two-dimensional Fourier transform spectroscopy. Strong coherent coupling occurs between certain types of excitons but is missing between other types of excitons because the distinctive nature of excitons results in different spatial overlap. Our finding may be applicable to other disordered systems, such as photosynthesis and conjugated polymers, where exciton coupling plays a critical role in determining charge and energy transfer.