Quantum control of two interacting electrons in a coupled quantum dot

Quantum-state engineering, i.e. active manipulation over the coherent dynamics ofsuitable quantum-mechanical systems, has become a fascinating prospect of modernphysics. Here we discuss the dynamics of two interacting electrons in a coupledquantum dot driven by an external electric field. The results show that the twoquantum dots can be used to prepare a maximally entangled Bell state by changingthe strength and duration of an oscillatory electric field. Different from thesuggestion made by Loss textit et al (1998 Phys. Rev. A 57 120, thepresent entanglement involves the spatial degree of freedom for the two electrons.We also find that the coherent tunnelling suppression discussed by Grossmanntextit et al (1991 Phys. Rev. Lett. 67 516 persists in thetwo-particle case: i.e. two electrons initially localized in one dot can remaindynamically localized, although the strong Coulomb repulsion prevents them frombehaving so. Surprisingly, the interaction enhances the degree of localization to alarge extent compared with that in the non-interacting case. This phenomenon isreferred to as the Coulomb-enhanced dynamical localization.