Bose-Einstein condensate as a quantum memory for a photonic polarization   qubit
  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 +/- 0.004. For long storage times, temporal fluctuations of the magnetic field reduce this value, yielding a lifetime of the fidelity of 1.1 +/- 0.2 ms. The write-read efficiency of the pulse energy can reach 0.53 +/- 0.05. 
Stefan Riedl, Matthias Lettner, Christoph Vo, Simon Baur, Gerhard   Rempe, and Stephan D\"urr
quant-ph