We investigate the dynamics of two interacting electrons confined to a pair of coupled quantum dots driven by an external ac field. By numerically integrating the two-electron Schrödinger equation in time, we find that for certain values of the strength and frequency of the ac field the electrons can become localized within just one of the dots, in spite of the Coulomb repulsion. Reducing the system to an effective two-site model of Hubbard type, and applying Floquet theory, leads to a detailed understanding of this effect. This demonstrates the possibility of using appropriate ac fields to manipulate entangled states in mesoscopic devices on extremely short time scales, which is an essential component of practical schemes for quantum information processing.
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