Related papers: Space-bounded computation: quantum is better than …

This paper has been withdrawn by the author.

This paper has been withdrawn. The main technical result will reappear in the new version of quant-ph/0501003.

The paper has been withdrawn

This preprint has been withdrawn.

This paper has been withdrawn by the author, due an error in the proof of Proposion 2.13.

The paper has been withdrawn due to numerical error.

This paper has been withdrawn as it has been superseded by 0808.2697

This paper has been withdrawn by the author

This paper has been withdrawn

This paper has been withdrawn by the author due to extremely unscientific errors.

This paper has been withdrawn due to non-clearness of some technical points, as well as lack of a reasonable statement of quantization conjecture.

The paper has been withdrawn by the author.

This paper has been withdrawn by the author due to errors.

This paper has been withdrawn by the authors, due a oversimplified decoherence model. It will be substituted by a new work.

This paper has been withdrawn as it has been superseded by postings arXiv:quant-ph/0702147 and arXiv:0712.2935

This paper has been withdrawn: it does not evade the no-go results of Mayers, Lo and Chau, to whom I am most grateful for helpful correspondences.

This paper has been withdrawn by the author.

This paper has been withdrawn since we combine this paper with math.AC/0503685. All contents of the paper have been moved to math.AC/0503685.

Paper has been withdrawn, see comment.

This paper has been withdrawn by the author because the conclusions reached in it are incorrect.