Coherent adiabatic theory of two-electron quantum dot molecules in external spin baths

Abstract

We derive an accurate molecular orbital based expression for the coherent time evolution of a two-electron wave function in a quantum dot molecule where the electrons interact with each other, with external time dependent electromagnetic fields and with a surrounding nuclear spin reservoir. The theory allows for direct numerical modeling of the decoherence in quantum dots due to hyperfine interactions. Calculations result in good agreement with recent singlet-triplet dephasing experiments by Laird et. al. [Phys. Rev. Lett. 97, 056801 (2006)], as well as analytical model calculations. Furthermore, it is shown that using a much faster electric switch than applied in these experiments will transfer the initial state to excited states where the hyperfine singlet-triplet mixing is negligible.

4 pages, 3 figures

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• Quantum control theory for coupled 2-electron dynamics in quantum dots
• Control of a two-electron quantum ring with an external magnetic field
• Fundamental Gates for a Strongly Correlated Two-Electron Quantum Ring