Dephasing of optically induced excitonic coherences in semiconductor heterostructures

Resonant optical excitation of a direct bandgap semiconductor below the band edge induces excitonic coherences. Experiments based on transient four-wave mixing or cw spectral-hole burning provide an excellent approach to eliminate inhomogeneous broadening and enable determination of the time scale and origin of the decay of the optically induced quantum coherence. Such measurements are of interest in basic physics since they reflect fundamental interactions between the exciton and the surrounding environment including, for example, lattice vibrations and interface fluctuations. They also relate to potential applications of these excitations such as in coherent control or quantum information processing.