Fig. 9: Coherence time obtained from Ramsey measurements.
From: Single ion qubit with estimated coherence time exceeding one hour
a without dynamical decoupling pulses and (b) with one spin-echo pulse. Blue points are experimental results and each point repeats 100 times. The solid lines are their fitting by the Gaussian decay function. (a) A small detuning between microwave frequency and qubit energy splitting is used here to observe the oscillation signal rather than the fringe contrast signal to wipe out the frequency drift effect. The coherence time is 1.6 ± 0.22 s. b The red-dashed line indicates the 1/e threshold. The coherence time is 11.1 ± 0.38 s.
