Related papers: cond-mat/9806011

The paper was withdrawn by the authors.

The paper has been withdrawn by the author.

This paper was withdrawn by the authors.

This paper has been withdrawn by the author(s),

This paper has been withdrawn by the author, due to the insecurity against attacks received in quant-ph/0605027v5.

This paper has been withdrawn.

The paper has been withdrawn by the authors

This paper has been withdrawn by the author.

This paper has been withdrawn by the author due to essential mistakes in some previous versions.

This paper has been withdrawn by the authors due to the fact that the conjecture has indeed already long been established.

This paper has been withdrawn by the author due to a crucial mistakes.

This paper has been withdrawn by the authors, due a oversimplified decoherence model.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This paper has been withdrawn by the author due to a crucial error.

The paper has been withdrawn

This paper has been withdrawn by the authors.

This paper has been withdrawn by the author.

This paper has been withdrawn

The paper has bene withdrawn by the author.

This paper is withdrawn. See quant-ph/9806031 for a discussion.

This paper has been withdrawn by the author