答え1
以下は、TikZ による計測メーター量子回路@Jasper Habicht の。
\documentclass[12pt]{article}
\usepackage{circuitikz}
\usetikzlibrary{arrows,decorations.pathreplacing}
\begin{document}
\tikzset{meter/.append style={draw, inner sep=10, rectangle, font=\vphantom{A}, minimum width=30, line width=.8, path picture={\draw[black] ([shift={(.1,.3)}]path picture bounding box.south west) to[bend left=50] ([shift={(-.1,.3)}]path picture bounding box.south east);\draw[black,-{Latex[length=8mm, width=1.8mm]}] ([shift={(0,.2)}]path picture bounding box.south) -- ([shift={(.4,-.1)}]path picture bounding box.north);}}}
\begin{circuitikz}
\node[meter] (meter) at (0,0) {};
\end{circuitikz}
\end{document}