FLUX QUANTIZATION

Φ = nΦ₀, Φ₀ = h/2e = 2.07×10⁻¹⁵ Wb

OBSERVABLES

Flux quanta (n)
Type
λ_L (penetration)
ξ (coherence)
Hc₁ / Hc₂
Φ = ∮ A·dl = nΦ₀ (London eq.)
In type-II SCs (κ > 1/√2), flux enters as Abrikosov vortices, each carrying exactly one flux quantum Φ₀. The order parameter vanishes at the vortex core (size ξ), and supercurrents circulate within the penetration depth λ.