Quantum dot decoherence measured by ensemble photoluminescence

We propose and experimentally demonstrate that a very simple, noninvasive, and common technique, i.e., standard nonresonant photoluminescence of large ensemble of quantum dots (QDs), can be used to determine the temperature dependence of homogeneous broadening. The method can be applied to a single quantum dot layer independently of the QD density and it allows to follow the increase of the homogeneous broadening up to high T. The experimental results show that different pictures apply depending on the QD size.