This issue contains papers on two interrelated active research areas: Quantum Information Science, and Numerical Ranges.
Some of the papers were presented at the Tenth Workshop on Numerical Ranges and Numerical Radii, Instytut Matematyki, Uniwersytet Jagiellonski in June, 2010. Some papers were submitted in response to our announcements on special issues on these subjects.
We would like to thank the contributors for this special issue, the organizers of the numerical range workshop, Franciszek Hugon Szafraniec and Jaroslav Zemanek, and the special editors, K. Audenaert, Y.T. Poon and T.Y. Tam.