Tuning quantum dot states with optical fields

The discrete states resulting from three-dimensional confinement in semiconductor quantum dots retain much of the character of their bulk-band origins, for example their angular momentum and effective mass. In addition they have many features of discrete atomic-like single particle states. Strong optical field interactions and reasonable dephasing rates make this system attractive for basic quantum optics experiments, as well as applications in quantum information sciences. However, semiconductor quantum dots have large inhomogeneous state broadens due to variations in size and shape. In addition, epitaxial semiconductor quantum dots, one of the classes in common use, rarely have ideal symmetry. Here we show how an optical technique can be used to fine-tune the transition energies of semiconductor quantum dots states and if desired restore targeted symmetry elements. This approach can be applied to establish degeneracies in biexciton-exciton decays to form discrete entangled photon pairs or to establish indistinguishability between different quantum dots.