2N qubit “mirror states” for optimal quantum communication S. Muralidharan, S. Karumanchi, S. Jain, R. Srikanth and P. K. Panigrahi Eur. Phys. J. D, 61 3 (2011) 757-763 Published online: 14 January 2011 DOI: 10.1140/epjd/e2010-09653-x