Figure 2
(a) Pulse sequence for two-level system, where \(x\) means the microwave is applied along \(x\) axis, the red bar is the idea \(\pi \) pulse (i.e. the swap gate), blue rectangles mean the evolution of \({H}_{S}\), which in the numerical calculations we always set it to be 0 without losing generalization. (b) Coherence vs evolution time with different distance between two swap gate, the variance of the random magnetic field is set to be 0.2 \(Gauss\). (c) Coherence time vs τ, which is defined in \(\mu {\rm{\Delta }}t=\tau \lambda {\rm{\Delta }}t\mathrm{/2}\). (d) is the values of \(|\tilde{f}(t,\omega {)|}^{2}\) which represent the noise spectrum. (e) The coherence vs time with different τ.
