D. DiVincenzo, and IBM. (2000)cite arxiv:quant-ph/0002077Comment: Prepared for Fortschritte der Physik special issue, Experimental Proposals for Quantum Computation. Version 2: many small corrections. Version 3: more small corrections & references added.
S. Szarek. (2003)cite arxiv:quant-ph/0310061Comment: 20 p., LATEX; an expanded version of the original submission: more background material from convexity and geometry of Banach spaces, more exhaustive bibliography and improved quality of references to the bibliography.