Question 429

What is a global phase?

Why does global phase usually not affect measurement results?

A

Because the hardware discards phase information at the start of each shot, keeping only amplitudes

B

Because multiplying the entire quantum state by the same phase always returns it to the state |0⟩

C

Because every phase, relative ones included, cancels out before the measurement is recorded

D

Because multiplying the entire quantum state by the same phase does not change measurement probabilities