We introduce the time-independent operators $a_\alpha^{\dagger}$ and $a_\alpha$ which create and annihilate, respectively, a particle in the single-particle state $\varphi_\alpha$. We define the fermion creation operator $a_\alpha^{\dagger}$ $$\begin{equation} a_\alpha^{\dagger}|0\rangle \equiv |\alpha\rangle \tag{1}, \end{equation}$$ and $$\begin{equation} a_\alpha^{\dagger}|\alpha_1\dots \alpha_n\rangle_{\mathrm{AS}} \equiv |\alpha\alpha_1\dots \alpha_n\rangle_{\mathrm{AS}} \tag{2} \end{equation}$$