Electron spin decoherence in quantum dots due to interaction with nuclei

Hyperfine interaction with nuclei was used to study the decoherence of a single electron spin in an isolated quantum dot. The spatial variation of the electron wave function within the dot caused the decay that lead to a nonuniform hyperfine coupling. The decay time was given by ℏN/A, where N is the number of nuclei inside the dot, and the amplitude of precession decayed to a finite value. A striking difference was found between the decoherence time for a single dot and the dephasing time for an ensemble of dots.