\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}