The coherence times of donor spin qubits in isotopically purified 28Si outperform theoretical predictions by two orders of magnitude. In their recently published article in Science Advances, the group of Andrea Morello found proof that this is due to a freeze-out of the spin polarization of the remaining 29Si nuclei in the presence of the donor bound electron. They measured the coherence times for the two cases of the system being frozen or evolving freely with the electron removed. The longer the nuclear bath was left unfrozen, the quicker the system lost its quantum information.
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