Time-resolved Faraday rotation has recently demonstrated coherent transfer ofelectron spin between quantum dots coupled by conjugated molecules. Using atransfer Hamiltonian ansatz for the coupled quantum dots, we calculate theFaraday rotation signal as a function of the probe frequency in a pump-probesetup using neutral quantum dots. Additionally, we study the signal of onespin-polarized excess electron in the coupled dots. We show that, in bothcases, the Faraday rotation angle is determined by the spin transferprobabilities and the Heisenberg spin exchange energy. By comparison of ourresults with experimental data, we find that the transfer matrix element forelectrons in the conduction band is of order 0.08 eV and the spin transferprobabilities are of order 10%.
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