如何实现这样的公式对齐

如何实现这样的排版：

\documentclass[aspectratio=169,10pt,notes=show]{beamer}
\usepackage{amsmath}
\begin{document}
\begin{frame}
\begin{align}
    \left[\mathcal{E} + eV - \frac{1}{2m}\left(\mathbf{p} + \frac{e}{c}\mathbf{A}\right)^2 + \frac{1}{2m_0c^2}\left(\mathcal{E} + eV\right)^2\right. \\ 
    \left. + i\frac{e\hbar}{(2m_0c)^2}\mathbf{E}\cdot\mathbf{p} - \frac{e\hbar}{2m_0c}\boldsymbol{\sigma}\cdot\mathbf{B} - \frac{e\hbar}{(2m_0c)^2}\boldsymbol{\sigma}\cdot\left(\mathbf{E} \times\mathbf{p}\right)\right]\psi = 0
  \end{align}
\end{frame}
\end{document}

不加入&时，可以正常编译，当我加入对齐符号&时，latex报错：

\left[\mathcal{E} + & eV - \frac{1}{2m}\left(\mathbf{p} + \frac{e}{c}\mathbf{A}\right)^2 + \frac{1}{2m_0c^2}\left(\mathcal{E} + eV\right)^2\right. \\ 
    \left. & + i\frac{e\hbar}{(2m_0c)^2}\mathbf{E}\cdot\mathbf{p} - \frac{e\hbar}{2m_0c}\boldsymbol{\sigma}\cdot\mathbf{B} - \frac{e\hbar}{(2m_0c)^2}\boldsymbol{\sigma}\cdot\left(\mathbf{E} \times\mathbf{p}\right)\right]\psi = 0

! Extra }, or forgotten \right.
<template> }
            $}\ifmeasuring@ \savefieldlength@ \fi \set@field \endtemplate 
l.9 \end{frame}

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