Expected output:

This note demonstrates the CONCEPT of ZNE using three noise levels.
The exact results depend on your hardware's noise characteristics.

On a perfect simulator:
  Scale 1: {'0': 1024}  → ⟨X⟩ = 1.0
  Scale 3: {'0': 1024}  → ⟨X⟩ = 1.0
  Scale 5: {'0': 1024}  → ⟨X⟩ = 1.0

On noisy hardware (example with 1% depolarizing error per CNOT):
  Scale 1: {'0': ~990, '1': ~34}   → ⟨X⟩ ≈ 0.93
  Scale 3: {'0': ~945, '1': ~79}   → ⟨X⟩ ≈ 0.85
  Scale 5: {'0': ~900, '1': ~124}  → ⟨X⟩ ≈ 0.76

Linear extrapolation to λ=0:
  ⟨X⟩₀ ≈ 0.93 + (0.93 - 0.85)/2 × 1 ≈ 0.97

The extrapolated value (0.97) is closer to the ideal (1.0)
than the raw measurement (0.93).

Richardson extrapolation with all three points gives even better results.