Radiatively limited dephasing in InAs quantum dots

Abstract

We measure the dephasing time of the exciton ground-state transition in ${\mathrm{In}}_{1\ensuremath{-}x}{\mathrm{Ga}}_{x}\mathrm{As}$ quantum dots using a sensitive four-wave mixing technique. We find experimental evidence that the dephasing time is given only by the radiative lifetime at low temperatures. We demonstrate the tunability of the radiatively limited dephasing time from $400\phantom{\rule{0.3em}{0ex}}\mathrm{ps}$ up to $2\phantom{\rule{0.3em}{0ex}}\mathrm{ns}$ in a series of annealed ${\mathrm{In}}_{1\ensuremath{-}x}{\mathrm{Ga}}_{x}\mathrm{As}$ quantum dots with increasing quantum-confinement energy from $69\phantom{\rule{0.3em}{0ex}}\mathrm{meV}\phantom{\rule{0.5em}{0ex}}\text{to}\phantom{\rule{0.5em}{0ex}}330\phantom{\rule{0.3em}{0ex}}\mathrm{meV}$.