Spectral hole burning and zero phonon linewidth in semiconductor nanocrystals

Spectral hole burning reveals a sharp zero-phonon line (ZPL) as well as discrete acoustic phonon sidebands in CdSe nanocrystals. The ZPL linewidth obtained from the spectral hole burning depends strongly on the measurement time scale, reflecting effects of spectral diffusion. The nonlinear optical measurement allows us to suppress effects of spectral diffusion leading to a ZPL linewidth as narrow as 6 mueV.