Comments: 4 pages including 5 figures, 3-page appendix with 2 figures, revtex4; v2: shortened, some references added; v3: Observation 2 improved, extension to many qubits discussed; v4: more details added to the Appendix, published version
Comments: See also arxiv:0909.3304. v1=v2. v3: Some bounds substantially improved. v4, v5: presentation improved. To appear in IEEE Transactions on Information Theory
Journal-ref: IEEE Trans. on Information Theory, vol. 57, pages 1548 - 1566
(2011)
Comments: 12 pages, 1 figure. Slightly expanded, material on phase space methods added, reference to arXiv:0709.1142 appended, replaced with published version
Comments: 7 pages, 9 figures, contribution to special issue of New J. Phys. on "Measurement-Based Quantum Information Processing". Replaced with published version
Comments: 5 pages. Special case of a result proved in quant-ph/0602001. The proof is greatly simplified, making the general case more accessible. To appear in Appl. Phys. B as part of the proceedings of the 2006 DPG Spring Meeting (Quantum Optics and Photonics section)