Our paper entitled Role of the electron spin in determining the coherence of the nuclear spins in a quantum dot was published in Nature Nanotechnology. The work is a close collaboration between the Poggio and Loss groups in Basel and our partners Arne Ludwig and Andreas Wieck in Bochum. Our motivation was to determine the limits set by the hyperfine interaction on the decoherence rate of an electron spin inside a quantum dot. To do this, we decided to measure the coherence of the nuclear spins as the nuclear spins have long-lived coherence in the absence of an electron. We found that the nuclear spin coherence time (as measured with a Hahn echo protocol) falls from several milli-seconds to around 20 μs on adding a single electron to the quantum dot. The nuclear spin recovers to its original value on adding two electrons pointing to a spin-based and not a charge-based decoherence mechanism (in the case of two electrons, a spin singlet is formed). We propose that a single electron mediates a nuclear spin-nuclear spin coupling, an RKKY-like effect. This hypothesis is backed up with a quantitative calculation. The paper was featured in UniNews.
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