Curator's Take
This article tackles a long‑standing blind spot in quantum verification by removing the i.i.d. assumption that most certification protocols rely on, making performance claims robust even when devices drift or exhibit memory effects. By providing rigorous confidence intervals for time‑averaged observables and a practical spot‑checking scheme, the work bridges the gap between idealized theory and real‑world hardware where correlated noise is inevitable. The approach could streamline quality control for near‑term processors and large‑scale quantum networks, though its statistical overhead still scales with the desired precision, so careful experimental design remains essential.
— Mark Eatherly
Summary
Standard quantum verification and certification protocols often assume that experimental sources emit independent and identically distributed (i.i.d.) states. In realistic scenarios, however, temporal drift, memory effects, feedback, and correlated noise can violate this assumption, causing standard analyses to underestimate uncertainty and overestimate device performance. Here, we introduce a framework for quantum verification and certification that remains valid without independence assumptions. Our method gives rigorous confidence intervals for the time-averaged expectation value of any fixed observable, even when each prepared state may depend on the previous experimental history. For full verification, we recover the standard i.i.d. sample-complexity scaling. For certification, we develop a spot-checking protocol that randomly selects a subset of states to certify an average target property of the remaining states, which are used for a parallel quantum task. We demonstrate the framework numerically for energy estimation and entanglement witnessing under drift, and experimentally for Bell-state certification on a quantum processor.