Beating of excitonic dressed states in a single quantum dot

We report picosecond control of excitonic dressed states in a single semiconductor quantum dot. A strong laser pulse couples the exciton and biexciton states, to form an Autler-Townes doublet of the neutral exciton transition. The Rabi-splitting, and hence the admixture of the dressed states follows the envelope of the picosecond control laser. We create a superposition of dressed states, and observe the resulting beat: a direct measurement of a Rabi oscillation in time-delay rather than the usual power domain. PACS numbers: 78.67.Hc, 42.50.Hz, 78.47.jm ∗Electronic address: [email protected]