Quantum memories,
C Simon, M Afzelius, J Appel, A B de la Giroday, S J Dewhurst, N Gisin, C Y Hu, F Jelezko, S Kroll, J H Muller, J Nunn, E S Polzik, J G Rarity, H De Riedmatten, W Rosenfeld, A J Shields, N Skold, R M Stevenson, R Thew, I A Walmsley, M C Weber, H Weinfurter, J Wrachtrup, R J Young,
European Physical Journal D 58, 1--22 (2010)