I am using this method to write description in a new line in beamer,

But how can I remove the indent at the new line so it aligns with the \item[]?
This is what I have right now.
\pdfminorversion=4
\documentclass{beamer}
\usetheme{Madrid}
\usepackage{appendixnumberbeamer}
\usepackage{textpos}
\usepackage{animate}
\usepackage{siunitx}
\usepackage{caption}
\usepackage{subcaption}
\begin{document}
\begin{frame}{title}
\fontsize{8pt}{9}\selectfont
\begin{columns}
\centering
\column{.7\textwidth}
\vbox to .8\textheight{%
\begin{figure}
\centering
\begin{subfigure}[b]{.5\textwidth}
\centering
\includegraphics[width=\textwidth]{../Fig1}
\end{subfigure}%\hfill
\begin{subfigure}[b]{.5\textwidth}
\centering
\includegraphics[width=\textwidth]{../Fig2}
\end{subfigure}\\\vfill
\begin{subfigure}[b]{.5\textwidth}
\centering
\includegraphics[width=\textwidth]{../Fig3}
\end{subfigure}%\hfill
\begin{subfigure}[b]{.5\textwidth}
\centering
\includegraphics[width=\textwidth]{../Fig4}
\end{subfigure}%
\end{figure}
}%
\column{.3\textwidth}
Imperfection in Tx and Rx may cause IQ imbalance and other system error.\\
\begin{description}[leftmargin=0pt]
\item[Gain Imbalance] \hfill \\Amplitude is different for I and Q.
\item[Quadrature Error] \hfill \\Phase between I and Q is not \ang{90}.
\item[IQ Offset] \hfill \\I and Q are not centered at zero.
\item[Gain Compression] \hfill \\Distance $d$ between constellation points is power dependent.
\end{description}
\end{columns}
\end{frame}
\end{document}



\setbeamersize{description width=-\labelsep}before the frame did not make any difference. – LWZ Sep 08 '13 at 22:45\begin{description}[leftmargin=0pt]delete[leftmargin=0pt]. – Gonzalo Medina Sep 08 '13 at 22:47