Figure 4

(a) Initial-state-specified fidelity of the SWAP gate at the finial time versus \({\bar{\Omega}}_{\mathrm{0m}}\). \(T=4\pi /{\bar{\Omega}}_{\mathrm{0m}}\) and \(\Omega _{\mathrm{0m}}={\bar{\Omega}}_{\mathrm{0m}}\) for the case of the constant pulse, while \(T=8\pi /{\bar{\Omega}}_{\mathrm{0m}}\) for the case of soft quantum control. (b) Initial-state-specified fidelity and populations of related states with evolution of time. \({\bar{\Omega}}_{\mathrm{0m}}/2\pi =2\text{ MHz}\) and other parameters are the same as those in Fig. 3(b)