Homogeneous linewidth in CdSe/ZnS core/shell nanocrystals

Abstract

Summary form only given. Understanding dephasing in quantum dots, especially dephasing due to electron-phonon interactions, is essential for the use of quantum dots as artificial atoms in applications such as quantum information processing. In this paper, we report experimental studies on dephasing in CdSe/ZnS core/shell nanocrystals using high resolution spectral hole burning. These studies not only allow us to determine the homogeneous linewidth, but also reveal directly discrete acoustic phonon sidebands. The extremely small homogeneous linewidth (32 /spl mu/eV) obtained at low temperature along with the nonlinear temperature dependence of the homogeneous linewidth indicates that the quantization of acoustic phonon modes leads to strong suppression of dephasing associated with electron-phonon interactions in nanocrystals. The dependence of the spectral hole width on the modulation frequency also reveals exciton spectral migration occurring on a time scale of order of 100 /spl mu/s.