Characterizing noise in QEC circuits

Quantum error correction (QEC) is essential for fault-tolerant quantum computing. QEC circuits protect quantum information from the effects of noise by encoding it across multiple physical qubits. Knowledge of the relevant characteristics of the noise that exists in devices while they run candidate QEC circuits can potentially enable the design of more efficient and reliable circuits for particular devices. For instance, knowldedge of bias, error spread, and possible error correlations can lead to circuits specifically targeted at correcting such errors as well as tailoring decoders designed for specific devices. Fast and efficient characterization also allows for verification and tailoring of error mitigation techniques, such as dynamic decoupling. I will discuss techniques for efficient characterisation of such noise, both at a holistic circuit level and at a phenomonological level, including data obtained from utilising such techniques on devices. Finally, the scale of data returned by these modern characterization techniques is such that we are rapidly approaching the stage where it will soon be unrealistic to attempt to analyse all the data obtained. I will discuss efficient methods of representing the data through scalable models and discuss how such models can be used in the push towards designing more efficient and reliable QEC circuits.