(a), (b) The diagram of Rabi frequency versus AWG amplitude by the two techniques. The linearity of DDS is better than that of mixing. (c), (d) The energy relaxtion decay and (e), (f) Ramsey oscillation obtained by DDS and mixing techniques, respectively. The uncertainties of the DDS technique are smaller than the mixing one. Here colored markers and black line denote the experimental results and fitted curve, respectively.