A note -- if you're linking to arXiv, it's better to link to the abstract (http://arxiv.org/abs/quant-ph/9908043, or http://arxiv.org/abs/quant-ph/9908043v3 for this particular version) rather than directly to the PDF. From the abstract, one can easily click through to the PDF; not so the reverse. And the abstract allows one to do things like see different versions of the paper, search for other things by the same authors, etc. Thank you!