Solution
= Solution
The flow equations of the displayed <vector field> are $\dot ψ_1=-ψ_2$ and $\dot ψ_2=ψ_1$. Hence $dψ/ds=iψ$, whose solution is $ψ(s)=e^{is}ψ(0)$. The vector field therefore generates the stated phase rotation.
= Solution
The flow equations of the displayed <vector field> are $\dot ψ_1=-ψ_2$ and $\dot ψ_2=ψ_1$. Hence $dψ/ds=iψ$, whose solution is $ψ(s)=e^{is}ψ(0)$. The vector field therefore generates the stated phase rotation.