答案1
我会这样做:
% In the preamble
% \usepackage{tikz}
% \usetikzlibrary{arrows.meta}
\begin{tikzpicture}
\node at (0,2.5) [] {$F(\mathcal{H})$};
\draw[] (0,0) circle[radius=2];
\draw[] (0,-0.5) circle[radius=1];
\node at (0,1) [] {$\tilde{\mathcal{H}}$};
\node (psi1) at (0,-0.5) [] {$\left\langle\psi\right|$};
\node at (5,2.5) [] {$\mathcal{H}$};
\draw[] (5,0) circle[radius=2];
\node (psi2) at (5,0) [] {$\left|\psi\right\rangle$};
\draw[Latex-Latex] (psi1) to[bend left] (psi2);
\end{tikzpicture}
其结果是: