Chapter 5 – Understanding the Qubit
Question 1
Which would provide visual information about the phase of a qubit—the Bloch sphere or the qsphere?
Answer
Both do. The Qiskit sphere (q-sphere) includes a checkbox to visualize the phase information. The Bloch sphere illustrates the phase by the position of the vector when it is out of phase, which is to say it is rotated about the z axis.
Question 2
Can you visualize multiple qubits on the Bloch sphere? If not, then describe why you wouldn’t.
Answer
No, we can’t visualize multi-qubits on the Bloch sphere as we can on the qsphere. The Bloch sphere is generally leveraged to illustrate a single qubit vector position for a given state, whereas the qsphere includes the phase. To represent multiple qubits using the Bloch sphere, you will need to have one Bloch sphere for each qubit.
Question 3
Write out the tensor product of three-qubit states in all forms.
Answer
The...
