简要地介绍量子计算中量子比特的纯态和混合态的量子描述,及其在Bloch球和庞加莱球上相应的表示.联系几何效应,从几何结构上对纯态的全局相位进行讨论,进而推广至混合态情形.
This paper briefly introduces the quantum description of pure state and mixed state in quantum computing, and its corresponding representation on Bloch sphere and Poincare sphere. Combining with geometric effect, this paper discusses the global phase of pure state from geometric structure, and then extended to the case of mixed state.