\documentstyle[12pt]{article}

\begin{document}

\begin{eqnarray*}
  \lambda = 0 \quad\Rightarrow\quad U = U_{\mathrm{bg}} + U_0 \\
  \lambda = 1 \quad\Rightarrow\quad U = U_{\mathrm{bg}} + U_1 
\end{eqnarray*}

\end{document}
