请不要自己重新造轮子

\documentclass{article}
\usepackage{lipsum}
\usepackage{enumitem}
\usepackage{graphicx}
\usepackage{paracol}

\begin{document}
\begin{enumerate}
  \item \lipsum[1]
    \columnratio{0.7}
    \begin{paracol}{2}
      \begin{itemize}[topsep=0pt, partopsep=0pt]
        \item \lipsum[2]
      \end{itemize}
      \switchcolumn
      \includegraphics[width=\linewidth]{example-image-a}
    \end{paracol}
\end{enumerate}
\end{document}

\documentclass[10pt]{beamer}

\usepackage{physics}
\usepackage{nicematrix}
\usepackage{tikz}
\usepackage{eqparbox}

\newcommand\eqbox[3][l]{\eqmakebox[#2][#1]{$#3$}}

\begin{document}
\begin{frame}{Matrix test}

\begin{equation*}
\begin{pNiceMatrix}[first-row, first-col]
  & \ket{\phi_{B}} & \ket{\varphi_{\varepsilon}} & \ket{\phi_{B}} & \ket{\varphi_{\varepsilon}} \\
  \eqbox{a}{\bra{\phi_{B}}} & A & A  & B  & B \\
  \eqbox{a}{\int \dd \varepsilon \bra{\varphi_{\varepsilon}}} & A & A & B & B \\
  \eqbox{a}{\bra{\phi_{B}}} & C & C  & D  & D \\
  \eqbox{a}{\int \dd \varepsilon \bra{\varphi_{\varepsilon}}} & C & C & D & D
\CodeAfter
\def\ys{1pt}
\tikz \draw[red, dashed, shorten <= 2pt, shorten >= 2pt, thick] ([yshift=\ys]3 -| 1) -- ([yshift=\ys]3 -| 5);
\tikz \draw[red, dashed, thick] (1 -| 3) -- (5 -| 3);
\end{pNiceMatrix}
\end{equation*}

\end{frame}

\end{document}

unicode-math的符号是在\AtBeginDocument里面导入的，所以要在正文重定义