Our paper entitled Decoupling a hole spin qubit from the nuclear spins was published in Nature Materials. An electron spin in a quantum dot interacts with the nuclear spins (via the hyperfine interaction) and this limits the spin dephasing times to quite modest values. What about a hole spin? Theory predicts that a heavy-hole spin decouples from the nuclear spins in an in-plane magnetic field. This is an idealized limit. How does it work out in practice? We have attempted to answer this question with an experiment: we apply an in-plane magnetic field, we measure the hole Zeeman frequency spectroscopically with an ultrahigh resolution technique (“coherent population trapping”, equivalently “dark-state spectroscopy”) and then look for changes in the hole Zeeman frequency as we polarize the nuclear spins. We tried to carry out this experiment several years ago but charge noise defeated us. Now though we have super-quiet hole devices thanks to the efforts of our partners Arne Ludwig and Andreas Wieck in Bochum and the dark-state spectroscopy works really nicely. The result? The hole spin decouples from the nuclear spins, even when we look with 10 neV resolution. The paper was featured in UniNews.
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