2016/02/26 by E. Kawakami, T. Jullien, P. Scarlino +8
Physics and Astronomy · #cond-mat.mes-hall
paper · pdf · doi:10.1073/pnas.1603251113
published as PNAS 2016 113 (42) 11738-11743
arxiv created 2016/02/26 · arxiv updated 2016/10/20
The gate fidelity and the coherence time of a qubit are important benchmarks for quantum computation. We construct a qubit using a single electron spin in a 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 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 - 1 MHz range, possibly because charge noise affecting the spin via the micromagnet gradient. This work shows that an electron spin in a Si/SiGe quantum dot is a good candidate for quantum information processing as well as for a quantum memory, even without isotopic purification.