Dynamically corrected gates suppress spatio-temporal error correlations as measured by randomized benchmarking

TL;DR

This paper demonstrates that dynamically corrected gates in quantum computing can significantly suppress spatial and temporal error correlations, improving the reliability of quantum operations in realistic noisy environments.

Contribution

The study provides the first experimental validation that dynamically corrected gates reduce error correlations in quantum circuits, beyond just lowering error magnitudes.

Findings

DCGs reduce error correlations by approximately 50 times.

Using DCGs increases uncorrelated errors linearly with their duration.

DCGs modify the error spectrum, effectively whitening the noise.

Abstract

Quantum error correction provides a path to large-scale quantum computers, but is built on challenging assumptions about the characteristics of the underlying errors. In particular, the mathematical assumption of statistically independent errors in quantum logic operations is at odds with realistic environments where error sources may exhibit strong temporal and spatial correlations. We present experiments using trapped ions to demonstrate that the use of dynamically corrected gates (DCGs), generally considered for the reduction of error magnitudes, can also suppress error correlations in space and time throughout quantum circuits. We present a first-principles analysis of the manifestation of error correlations in randomized benchmarking, and validate this model through experiments performed using engineered errors. We find that standard DCGs can reduce error correlations by $\sim50\times$, while increasing the magnitude of uncorrelated errors by a factor scaling linearly with the extended DCG duration compared to a primitive gate. We then demonstrate that the correlation characteristics of intrinsic errors in our system are modified by use of DCGs, consistent with a picture in which DCGs whiten the effective error spectrum induced by external noise.