Zero-Noise Extrapolation Lab

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 simulator models a noisy quantum circuit measuring ⟨Z⟩ = cos θ of a target rotation, runs it at five amplified noise-scale factors (unitary folding, λ = 1…3), and fits a polynomial through the noisy measurements to extrapolate back to the physically unreachable zero-noise point. 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.