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

• URL: http://arxiv.org/abs/2203.01101v2
• Date: Fri, 10 Jun 2022 11:00:23 GMT
• Title: Approaching ideal visibility in singlet-triplet qubit operations using energy-selective tunneling-based Hamiltonian estimation
• Authors: Jehyun Kim, Jonginn Yun, Wonjin Jang, Hyeongyu Jang, Jaemin Park, Youngwook Song, Min-Kyun Cho, Sangwoo Shim, Hanseo Sohn, Hwanchul Jung, Vladimir Umansky, and Dohun Kim
• Abstract summary: We report energy selective tunneling readout-based Hamiltonian parameter estimation of a two-electron spin qubit in a GaAs quantum dot array. For qubit operation in a frequency heralded mode, we observe a 40-fold increase in coherence time without resorting to nuclear polarization.
• Score: 0.42499766840638903
• License: http://arxiv.org/licenses/nonexclusive-distrib/1.0/
• 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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