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arXiv · 2203.01101

Approaching ideal visibility in singlet-triplet qubit operations using energy-selective tunneling-based Hamiltonian estimation

Jehyun Kim·Jonginn Yun·Wonjin Jang·Hyeongyu Jang·Jaemin Park·Youngwook Song·Min-Kyun Cho·Sangwoo Shim·Hanseo Sohn·Hwanchul Jung·Vladimir Umansky·Dohun Kim
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Abstract

We report energy selective tunneling readout-based Hamiltonian parameter estimation of a two-electron spin qubit in a GaAs quantum dot array. Optimization of readout fidelity enables a single-shot measurement time of 16 on average, with adaptive initialization and efficient qubit frequency estimation based on real-time Bayesian inference. For qubit operation in a frequency heralded mode, we observe a 40-fold increase in coherence time without resorting to dynamic nuclear polarization. We also demonstrate active frequency feedback with quantum oscillation visibility, single-shot measurement fidelity, and state initialization fidelity up to 97.7%, 99%, and over 99.7%, respectively. By pushing the sensitivity of the energy selective tunneling-based spin to charge conversion to the limit, the technique is useful for advanced quantum control protocols such as error mitigation schemes, where fast qubit parameter calibration with a large signal-to-noise ratio is crucial.

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Jehyun Kim, Jonginn Yun, Wonjin Jang, Hyeongyu Jang, Jaemin Park, Youngwook Song, Min-Kyun Cho, Sangwoo Shim, Hanseo Sohn, Hwanchul Jung, Vladimir Umansky, Dohun Kim. 2022-03-02. Approaching ideal visibility in singlet-triplet qubit operations using energy-selective tunneling-based Hamiltonian estimation. https://doi.org/10.1103/physrevlett.129.040501

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