\documentclass{standalone}
\usepackage{binarytree}

\begin{document}
\btreeset{%
 math labels,%
 separate,%
 level distance scales=false,%
 sibling distance scales=false,%
 continue after turn=false,%
 continue at path end=false,%
 left label anchor=center,%
 right label anchor=center}

\BinaryTree{l:\nwarrow!r:\nearrow,r:\nearrow!l:\nwarrow}{3}
\end{document}