Electrons in a cryogenic planar Penning trap and experimental challenges for quantum processing P. Bushev, S. Stahl, R. Natali, G. Marx, E. Stachowska, G. Werth, M. Hellwig and F. Schmidt-Kaler Eur. Phys. J. D, 50 1 (2008) 97-102 Published online: 03 October 2008 DOI: 10.1140/epjd/e2008-00186-y