In a superconductor, the electrons form a quantum superconducting condensate, called a Bardeen–Cooper–Schrieffer (BCS) condensate. In the BCS condensate all electrons behave coherently, i.e. as one particle. Thus the phase of the collective BCS wavefunction behaves under the influence of the vector potential A in the same way as the phase of a single electron. Therefore, the BCS condensate flowing around a closed path in a multiply connected superconducting sample acquires a phase difference Δ φ determined by the magnetic flux Φ B through the area enclosed by the path (via Stokes' theorem and ∇ ∇ × × A = B ), and given by: