Zero-Noise Extrapolation Lab (2D)

Zero-noise extrapolation (ZNE) is the leading error-mitigation technique used on today's real quantum hardware — no extra qubits, no error-correcting codes, just deliberately noisier circuit runs and a curve fit. This 2D version renders the same physics as a pannable, zoomable data plot: a noisy quantum circuit measuring ⟨Z⟩ = cos θ of a target rotation is run at five amplified noise-scale factors (unitary folding, λ = 1…3), and a polynomial is fit through the noisy measurements to extrapolate back to the physically unreachable zero-noise point. A second panel diagrams the actual folded-gate circuit — G·G⁻¹·G stacks that make each layer noisier — for whichever measured point you select. Adjust the hardware error rate, circuit depth and target angle to see how badly noise biases the raw measurement, switch between a linear and a quadratic (Richardson) fit to see which recovers the true value better, and resample the shot noise to see the technique hold up across repeated runs.