We report a spectroscopic study of single colloidal $\mathrm{CdSe}/\mathrm{ZnS}$ nanocrystals at low temperature. We use photon-correlation Fourier spectroscopy, a technique based on measuring the correlations of the intensities detected at the outputs of a Michelson interferometer. Spectral diffusion over a few $\mu \mathrm{eV}$ is evidenced, on a typical time scale of $200\mu \mathrm{s}$. A time resolution as high as $20\mu \mathrm{s}$ is obtained, and an upper limit of $6.5\mu \mathrm{eV}$ emission linewidth is measured, corresponding to a coherence time of at least 200 ps, similar to the values for epitaxial quantum dots.

• Received 27 July 2007

DOI:https://doi.org/10.1103/PhysRevLett.100.027403