Superposition Principle for Qubit States in the Spin-Projection Mean Representation

We formulate the superposition principle of two states of qubit as a nonlinear addition rule of mean values of spin projections onto three perpendicular directions and obtain explicit expressions for the mean values determining the superposition states in terms of the mean values of two initial pure states of the qubit.

Automated summary

This passage discusses the superposition principle of a qubit, formulating it as a nonlinear addition rule of the mean values of spin projections onto three perpendicular directions. It also provides explicit expressions for the mean values that determine the superposition states, based on the mean values of two initial pure states of the qubit.