Reilly, D. J. and Taylor, J M and Laird, E. A. and Petta, J R and Marcus, C M and Hanson, M P and Gossard, A C (2008) Measurement of Temporal Correlations of the Overhauser Field in a Double Quantum Dot. Physical review letters, 101 (23). ISSN 0031-9007
Full text not available from this repository.Abstract
In quantum dots made from materials with nonzero nuclear spins, hyperfine coupling creates a fluctuating effective Zeeman field (Overhauser field) felt by electrons, which can be a dominant source of spin qubit decoherence. We characterize the spectral properties of the fluctuating Overhauser field in a GaAs double quantum dot by measuring correlation functions and power spectra of the rate of singlet-triplet mixing of two separated electrons. Away from zero field, spectral weight is concentrated below 10 Hz, with ∼ 1 / f 2 dependence on frequency f . This is consistent with a model of nuclear spin diffusion, and indicates that decoherence can be largely suppressed by echo techniques.