Edit and compile if you like:
\documentclass[tikz]{standalone}\usepackage{mathtools}\let\Im\relax\DeclareMathOperator{\Im}{Im}\let\Re\relax\DeclareMathOperator{\Re}{Re}\usetikzlibrary{decorations.markings,positioning}\providecommand{\poles}{\node (poles) at (2.5,1.5) {poles of $h(p_0)$};\draw[fill](1.5,3) coordinate [circle,fill,inner sep=1pt,label=right:$p_1$] (p1)(2,-2) coordinate [circle,fill,inner sep=1pt,label=below:$p_2$] (p2)(-3,1) coordinate [circle,fill,inner sep=1pt,label=above:$p_3$] (p3)(-2,-1.5) coordinate [circle,fill,inner sep=1pt,label=above:$p_4$] (p4);\draw[ultra thin,gray] (poles) -- (p1) (poles) -- (p2) (poles.west) -- (p3) (poles) -- (p4);}\providecommand{\polecontours}{\draw[blue!60!black,decoration={markings,mark=between positions 0.03 and 1.03 step 0.125 with \arrow{<}},postaction={decorate}] (p1) circle (0.5) node [below=0.5] {$C_1$} (p2) circle (0.5) node [below=0.5] {$C_2$} (p3) circle (0.5) node [below=0.5] {$C_3$} (p4) circle (0.5) node [below=0.5] {$C_4$};}\begin{document}\begin{tikzpicture}[thick]\def\xr{3} \def\yr{3}% Axes\draw [->] (-\xr-1,0) -- (\xr+1,0) node [above left] {$\Re(p_0)$};\draw [->] (0,-\yr-1) -- (0,\yr+1) node [below left=0.2 and 0] {$\Im(p_0)$};% Matsubara frequencies\foreach \n in {-\yr,...,-1,1,2,...,\yr}{%\draw[fill] (0,\n) circle (1pt) node [right,font=\footnotesize] {$i \mkern1mu \omega_{_{\n}}$};}\draw[fill] (0,0) circle (1pt) node [above right] {0};% Contour line\draw[blue!60!black,decoration={markings,mark=between positions 0.125 and 0.875 step 0.25 with \arrow{>}},postaction={decorate}] circle (\yr+1) node [below right=0.925*\xr and 0.925*\yr] {$C$};
Click to download: contour-2.tex
Open in Overleaf: contour-2.tex
This file is available on tikz.netlify.app and on GitHub and is MIT licensed.
See more on the author page of Janosh Riebesell..