Fig. 7. (Color online) A qubit on the Bloch sphere, first (a) initialized to (
0 +
1)/
2 at time
t=0 and then left alone. Due to noise it accumulates a random phase
φ, so (b) at time
t the qubit state is (
0 +
eiφ1)/
2. This is shown as a spread of the Bloch vector[
27] [Master’s Thesis in Physics, Stockholm University, 2020].
