Question

If a superconducting Quantum Interference Device which consists of a 3 mm ring can measure 1/5,000 of a fluxon, calculate the magnetic field that can be detected (1 fluxon, φ₀ = h/2e = 2.0678 × 10⁻¹⁵Tm², is the smallest unit of flux).

Answer 1

ΔB = ϕ/A = (1/5, 000)ϕ₀/π(3 × 10⁻³)²

Substituting φ₀ = 2.0678 × 10⁻¹⁵ Tm², we get

ΔB = 2.93 × 10⁻¹⁴T