In this section, you will learn the physics behind superposition and how to explain it. You will learn about quantum measurement of a single qubit and how to represent it on the Bloch sphere.
In this chapter, we've already dealt with the concept of superposition of single qubits: two or more qubits combined to produce another qubit.
Some of these examples of superposition are when we wrote |"+">, |"-">,
or
in terms of |"0"> and |"1">. None of |"+">, |"-">,
or
are 100% |"0"> or 100% |"1">; they are all a mixture of each. |"0"> and |"1"> can also be written as a combination of other qubits. We can write both as a combination of |"+">, |"-"> or a combination of
and
, for example:
And for |"1"> we can write these combinations as follows:
