We introduce a solid-state qubit in which exchange interactions among confined electrons provide both the static longitudinal field and the oscillatory transverse field, allowing rapid and full qubit control via rf gate-voltage pulses. We demonstrate two-axis control at a detuning sweet-spot, where leakage due to hyperfine coupling is suppressed by the large exchange gap. A {\pi}/2-gate time of 2.5 ns and a coherence time of 19 {\mu}s, using multi-pulse echo, are also demonstrated. Model calculations that include effects of hyperfine noise are in excellent quantitative agreement with experiment.
@article{arxiv.1304.3413,
title = {The Resonant Exchange Qubit},
author = {J. Medford and J. Beil and J. M. Taylor and E. I. Rashba and H. Lu and A. C. Gossard and C. M. Marcus},
journal= {arXiv preprint arXiv:1304.3413},
year = {2014}
}