Bichromatic resonant light scattering from a quantum dot

We report on resonant light scattering experiments in which a single InAs quantum dot is exposed to two independently tunable continuous-wave lasers while the scattered light is analyzed background free, with high spectral and temporal resolution. In contrast to the well-known monochromatic case exhibiting Rabi oscillations, in this bichromatic case the additional field introduces oscillations at half the difference of the laser frequencies and harmonics thereof, persisting beyond the natural lifetime. The familiar dressed-states ladder now contains an infinite number of levels per manifold. With suitable averaging, the rich resulting spectra and second-order correlations can be reproduced accurately using the Bloch equations and the quantum regression theorem.