Bose-Einstein condensate as a quantum memory for a photonic polarization qubit

Abstract

A scheme based on electromagnetically induced transparency is used to store light in a Bose-Einstein condensate. In this process, a photonic polarization qubit is stored in atomic Zeeman states. The performance of the storage process is characterized and optimized. The average process fidelity is $1.000\ifmmode\pm\else\textpm\fi{}0.004$. For long storage times, temporal fluctuations of the magnetic field reduce this value, yielding a lifetime of the fidelity of $(1.1\ifmmode\pm\else\textpm\fi{}0.2)$ ms. The write-read efficiency of the pulse energy can reach $0.53\ifmmode\pm\else\textpm\fi{}0.05$.