Stimulated emission from the biexciton in a single quantum dot

Using two optical pulses of different frequencies, we demonstrate entanglement and disentanglement of the electronic states in Stranski-Krastanov quantum dots. Resonant two-photon excitation of the biexciton creates an entangled Bell-like state. The second pulse, being resonant to the exciton-biexciton transition, stimulates the emission from the biexciton and fully disentangles the two-bit system. By setting the polarization of the stimulation pulse, we control the recombination path of the biexciton and, by this, the state of the photons emitted in the decay cascade.