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arXiv · 1412.1503

Characterizing gate operations near the sweet spot of an exchange-only qubit

Jianjia Fei·Jo-Tzu Hung·Teck Seng Koh·Yun-Pil Shim·S. N. Coppersmith·Xuedong Hu·Mark Friesen
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Abstract

Optimal working points or "sweet spots" have arisen as an important tool for mitigating charge noise in quantum dot logical spin qubits. The exchange-only qubit provides an ideal system for studying this effect because $Z$ rotations are performed directly at the sweet spot, while $X$ rotations are not. Here for the first time we quantify the ability of the sweet spot to mitigate charge noise by treating $X$ and $Z$ rotations on an equal footing. Specifically, we optimize $X$ rotations and determine an upper bound on their fidelity. We find that sweet spots offer a fidelity improvement factor of at least 20 for typical GaAs devices, and more for Si devices.

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Jianjia Fei, Jo-Tzu Hung, Teck Seng Koh, Yun-Pil Shim, S. N. Coppersmith, Xuedong Hu, Mark Friesen. 2015-03-13. Characterizing gate operations near the sweet spot of an exchange-only qubit. https://doi.org/10.1103/physrevb.91.205434

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