Adjust vertical size of \sqrt contating terms with subscript and superscript

Question

In the second \sqrt,

both the subscript and superscript are \smashed:

a_{\smash{0}}^{\smash{2}

Yet, the sqrt are of different sizes?

How do I get the second \sqrt to be the exact vertical size of the first?

Notes:

• The tikz drawing is only to show that the two \sqrt are of different size.
• I do not want to adjust the size of the first \sqrt to match the second.

Code:

\documentclass{article}
\usepackage{amsmath}
\usepackage{tikz}% <--- ONLY to show that the symbols are of different size

\newcommand{\MyTikzMark}[2]{%
    \tikz[baseline,remember picture] \node[anchor=base,inner sep=0pt] (#1) {$\displaystyle#2$};%
}%

\begin{document}
\[
    \MyTikzMark{Left Marker}{\sqrt{\overline{q}}} \sqrt{\overline{q}a_{\smash{0}}^{\smash{2}}}
\]
\begin{tikzpicture}[remember picture, overlay, dotted]
    \draw [red] ([shift={(-2ex,-1pt)}]Left Marker.north) -- ++(10.0ex,0);
    \draw [red] ([shift={(-2ex,+0pt)}]Left Marker.south) -- ++(10.0ex,0);
\end{tikzpicture}%
\end{document}

Answer 1

You do get the same square root sign; contrary to what you believe, TikZ enters in the picture. However, you have to smash the full new contents.

\documentclass{article}
\usepackage{amsmath}

\usepackage{tikz}% <--- ONLY to show that the symbols are of different size

\newcommand{\MyTikzMark}[2]{%
    \tikz[baseline,remember picture] \node[anchor=base,inner sep=0pt] (#1) {$#2$};%
}%


\begin{document}
\begin{gather*}
\sqrt{\overline{q}} \sqrt{\overline{q}\smash{a_{0}^{2}}}
\\
\MyTikzMark{Left Marker}{\displaystyle\sqrt{\overline{q}}}
\sqrt{\overline{q}\smash{a_{0}^{2}}}
\\
\MyTikzMark{Left Marker B}{\sqrt{\overline{q}}}
\textstyle\sqrt{\overline{q}\smash{a_{0}^{2}}}
\end{gather*}
\begin{tikzpicture}[remember picture, overlay, dotted]
    \draw [red] ([xshift=-2ex]Left Marker.north) -- ++(10.0ex,0);
    \draw [red] ([xshift=-2ex]Left Marker.south) -- ++(10.0ex,0);
    \draw [red] ([xshift=-2ex]Left Marker B.north) -- ++(10.0ex,0);
    \draw [red] ([xshift=-2ex]Left Marker B.south) -- ++(10.0ex,0);
\end{tikzpicture}

\end{document}