Single ion qubit with estimated coherence time exceeding one hour

Abstract Realizing a long coherence time quantum memory is major challenge of current technology. Until now, the longest coherence-time single qubit was reported as 660 s in 171 Yb + ion-qubit through technical developments sympathetic cooling and dynamical decoupling pulses, which addressed heating-induced detection inefficiency magnetic field fluctuations. However, it not clear what prohibited further enhancement. Here, we identify suppress limiting factors, are remaining magnetic-field fluctuations, frequency instability leakage microwave reference-oscillator. Then, observe around 5500 for ion-qubit, constant exponential decay fit from measurements up to 960 s. We also systematically study decoherence process by using tomography analyze results applying recently developed resource theories coherence. Our experimental demonstration will accelerate practical applications memories various information processing, especially noisy-intermediate-scale regime.