Related papers: Optimality of the Heisenberg limit for continuous-…

This paper has been withdrawn by the authors. We have discovered an error in the evaluation of the diagram, which invalidates our conclusion.

This paper has been withdrawn by the authors. We have discovered an error in the evaluation of the diagram, which invalidates our conclusion.

This paper has been withdrawn by the author due to essential mistakes in some previous versions.

This paper has been withdrawn by the authors because M. Aschenbrenner pointed out that the proof of theorem 3.1 was incorrect.

This paper has been withdrawn by the authors due to some errors.

This paper has been withdrawn by the author

This paper has been withdrawn by the author(s), due a mistake of factor 1/2.

This paper has been withdrawn by the author due to a crucial sign error in equation 1.

This paper has been withdrawn by the authors because the paper is largely revised and improved, and to appear in Mechanics Research Communications.

This paper has been withdrawn by the author(s), due a crucial sign error in Thm. 11.

This paper has been withdrawn.

This paper has been withdrawn by the author due to an error in the proof of Theorem 1.

This paper has been withdrawn by the authors due to crucial error in the main proof (located in Section 2.4). The authors apologize for any inconveniences.

This paper has been withdrawn by the authors due to an error.

This paper has been withdrawn by the author(s) in the light of several other works available and due to a misunderstanding in the authorships.

This paper has been withdrawn by the authors due to a mistake in one of the proofs

This paper has been withdrawn by the authors, due a crucial error in the proof of the main theorem.

This paper has been withdrawn by the author.

This paper has been withdrawn by the author due to some error in the result

This paper has been withdrawn by the author(s). Please refer to quant-ph/0311171.