Radiatively limited dephasing in InAs quantum dots

We measure the dephasing time of the exciton ground-state transition in In_1-xGaₓAs 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 4000.3em0exps up to 20.3em0exns in a series of annealed In_1-xGaₓAs quantum dots with increasing quantum-confinement energy from 690.3em0exmeV0.5em0exto0.5em0ex3300.3em0exmeV.