Electron Localization due to Symmetry Breaking in Nonlinear Coupled-Quantum Systems

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Abstract
The effects of nonlinear coupling due to on-site nonlinearlity (Coulomb-charging potential) on dynamic behaviors in coupled-quantum systems are investigated for a number of coupled dots N of 3–17 with a circular-chain configuration. For the initial condition that all dots have the same electron occupation probability, a small initial fluctuation in the electron population causes symmetry-breaking instability of the electron distribution in the coupled-quantum system when the Coulomb-charging potential exceeds a certain threshold value. The threshold value is maximum at N=3 (2.25 times larger than that at N=2) and gradually decreases as the number of coupled dots increases.