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The gate fidelity and the coherence time of a quantum bit (qubit) are important benchmarks for quantum computation. We construct a qubit using a single electron spin in an Si/SiGe quantum dot and control it electrically via an artificial spin-orbit field from a micromagnet. We measure an average single-qubit gate fidelity of ∼99% using randomized benchmarking, which is consistent with dephasing from the slowly evolving nuclear spins in the substrate. The coherence time measured using dynamical decoupling extends up to ∼400 μs for 128 decoupling pulses, with no sign of saturation. We find evidence that the coherence time is limited by noise in the 10-kHz to 1-MHz range, possibly because charge noise affects the spin via the micromagnet gradient. This work shows that an electron spin in an Si/SiGe quantum dot is a good candidate for quantum information processing as well as for a quantum memory, even without isotopic purification.

Original languageEnglish
Pages (from-to)11738-11743
Number of pages6
JournalProceedings of the National Academy of Sciences of the United States of America
Issue number42
Publication statusPublished - 18 Oct 2016

    Research areas

  • Dynamical decoupling, Electron spin, Qubit, Randomized benchmarking, Si/SiGe quantum dot

ID: 38016567