A charged particle traversing two paths encircling a solenoid acquires a quantum phase difference even though the magnetic field is zero along both paths.
Where Φ₀ = h/e ≈ 4.136×10⁻¹⁵ Wb is the magnetic flux quantum. The two wavepackets interfere constructively or destructively depending on the enclosed flux.
The visualization shows two paths (blue upper, green lower) combining at the detector. Watch the interference fringe shift as you vary the flux.