Hyperfine interaction-dominated dynamics of nuclear spins in self-assembled InGaAs quantum dots.

Institute of Quantum Electronics, ETH-Zürich, Zürich, Switzerland.
Physical Review Letters (Impact Factor: 7.73). 10/2011; 107(16):167401. DOI: 10.1103/PhysRevLett.107.167401
Source: PubMed

ABSTRACT We measure the dynamics of nuclear spins in a single-electron charged self-assembled InGaAs quantum dot with negligible nuclear spin diffusion due to dipole-dipole interaction and identify two distinct mechanisms responsible for the decay of the Overhauser field. We attribute a temperature-independent decay lasting ∼100 sec at 5 T to intradot diffusion induced by hyperfine-mediated indirect nuclear spin interaction. By repeated polarization of the nuclear spins, this diffusion induced partial decay can be suppressed. We also observe a gate voltage and temperature-dependent decay stemming from cotunneling mediated nuclear spin flips that can be prolonged to ∼30 h by adjusting the gate voltage and lowering the temperature to ∼200 mK. Our measurements indicate possibilities for exploring quantum dynamics of the central spin model.

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