Beyond Orbital Rotations: Correlation-Rank Limits and Clifford-Accessible Measurement, from Algebra and Global Optimization
The paper investigates measurement limits for electronic observables, showing that relying only on orbital rotations is insufficient for certain correlated measurements. It establishes a fixed-sector correlation-rank obstruction, proving that at least three orbital settings are needed to capture some correlations. However, incorporating a single physical Clifford circuit measurement can achieve these results with a certified 31–70% reduction in the required shot budget.