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arXiv · 1803.01062

Spin decoherence in a two-qubit CPHASE gate: the critical role of tunneling noise

Peihao Huang·Neil M. Zimmerman·Garnett W. Bryant
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Abstract

Rapid progress in semiconductor spin qubits has enabled experimental demonstrations of a two-qubit logic gate. Understanding spin decoherence in a two-qubit logic gate is necessary for optimal qubit operation. We study spin decoherence due to $1/f$ charge noise for two electrons in a double quantum dot used for a two-qubit controlled-phase gate. In contrast to the usual belief, spin decoherence can be dominated by the tunneling noise from $1/f$ charge noise instead of the detuning noise. Tunneling noise can dominate because the effect of tunneling noise on the spin qubit is first order in the charge admixture; while the effect of the detuning noise is only second order. The different orders of contributions result in different detuning dependence of the decoherence, which provides a way to identify the noise source. We find that decoherence in a recent two-qubit experiment was dominated by the tunneling noise from $1/f$ charge noise. The results illustrate the importance of considering tunneling noise to design optimal operation of spin qubits.

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Peihao Huang, Neil M. Zimmerman, Garnett W. Bryant. 2018-03-02. Spin decoherence in a two-qubit CPHASE gate: the critical role of tunneling noise. https://doi.org/10.1038/s41534-018-0112-0

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