Related papers: All-Electric Quantum Point Contact Spin Valve

This paper has been withdrawn.

This paper has been withdrawn by the author.

This paper has been withdrawn by the author due to a crucial error related with the consideration of regular points

This paper has been withdrawn by the authors because it was just an early submission of quant-ph/0308133 with the wrong title. Sorry.

This paper has been withdrawn by the author

This paper has been withdrawn by the author due to a crucial sign error in equation 1

There have been comments on the starting paper, hep-th/0106074, which point out unclear motivation and definitions on noncommutative momentum introduced. Therefore, to give more clear presentation, this paper is withdrawn.

This paper has been withdrawn by the author(s)

This paper has been withdrawn by the author due to errors.

The paper has been withdrawn by the author, due to a critical error stemming from the defined template.

The paper has been withdrawn by the author.

The paper has been withdrawn by the author, due to it being fundamentally flawed. The author apologizes for any inconvenience it may have caused.

This paper has been withdrawn by the author, due to a significant error in section 4.3.1.

This paper has been withdrawn by the author due to a crucial sign error in equation 1

This paper has been withdrawn since it was an inadvertant double submission. An updated version of the original submission can be found at quant-ph/0505131

There have been comments on this paper which point out unclear motivation and definitions on noncommutative momentum introduced. Therefore, this paper is withdrawn by the author for more clear presentation.

This has been withdrawn by the author. A rewrite of some of the material is currently in progress.

The paper has been withdrawn

This paper has been withdrawn by the author, due to a crucial error in the proof of Thm.1

The paper was withdrawn by the author. Further research is needed.