Coupling nanocrystals to a high-$Q$ silica microsphere: Entanglement in quantum dots via photon exchange

Coupling nanocrystals (quantum dots) to a high-$Q$ whispering gallery mode (WGM) of a silica microsphere, can produce a strong coherent interaction between the WGM and the electronic states of the dots. Shifting the resonance frequencies of the dots, for instance by placing the entire system in an electric potential, then allows this interaction to be controlled, permitting entangling interactions between different dots in a way analogous to the ion-trap computer of Cirac and Zoller. Thus, a more advanced system of this type could potentially be used to implement a simple quantum computer.