\documentclass{standalone}
\usepackage{tikz}

\usetikzlibrary{automata,arrows,positioning}
\usetikzlibrary{arrows.meta,chains,shapes.geometric}
\usetikzlibrary{decorations.pathreplacing}

\begin{document}

\begin{tikzpicture}[shorten >=1pt,node distance=2cm,on grid,auto]
   \node[state,initial] (q_a)   {$q_a$}; 
   \node[state,accepting] (q_b) [right=of q_a] {$q_b$}; 
    \path[->] 
    (q_a) edge [loop above] node {a} ()

    (q_0) edge  node {0} (q_1)
          edge  node [swap] {1} (q_2)
    (q_1) edge  node  {1} (q_3)
          edge [loop above] node {0} ()
    (q_2) edge  node [swap] {0} (q_3) 
          edge [loop below] node {1} ();
\end{tikzpicture}

\end{document}