Bloch Sphere for Topologists

摘要

The author uses this note to clear up some of the mysteries of the Bloch sphere representation of pure states. The Bloch sphere is a representation of a pure state as a point on the unit sphere S(sup 2) proper subset R(sup 3). Pure state kets that are norm one scalar multiples of each other share the same representation. The author shall make this clear. He makes no claims of originality in this note. His purpose is to simply explain some of the basics of quantum information.