Homogeneous broadening of theStoPtransition in InGaAs/GaAs quantum dots measured by infrared absorption imaging with nanoscale resolution

Abstract

Absorption of single InGaAs self-assembled quantum dots is spatially resolved in resonance with the $S$ to $P$ polaron transitions around $\ensuremath{\lambda}=25 \ensuremath{\mu}\mathrm{m}$ wavelength. We show that the spatial resolution down to 50 nm ($\ensuremath{\lambda}/500$) combined with the analysis of the absorption nanoscopy images provides a measurement of the homogeneous broadening at room temperature. The $2.5\ifmmode\pm\else\textpm\fi{}1$ meV measured $S$-$P$ homogeneous broadening supports the calculated value accounting for acoustic phonon-induced decoherence.