  Current hardware for quantum computing suffers from high levels of noise, and
so to achieve practical fault-tolerant quantum computing will require powerful
and efficient methods to correct for errors in quantum circuits. Here, we
explore the role and effectiveness of using noise tailoring techniques to
improve the performance of error correcting codes. Noise tailoring methods such
as randomized compiling (RC) convert complex coherent noise processes to
effective stochastic noise. While it is known that this can be leveraged to
design efficient diagnostic tools, we explore its impact on the performance of
error correcting codes. Of particular interest is the important class of
coherent errors, arising from control errors, where RC has the maximum effect
-- converting these into purely stochastic errors. For these errors, we show
here that RC delivers an improvement in performance of the concatenated Steane
code by several orders of magnitude. We also show that below a threshold
rotation angle, the gains in logical fidelity can be arbitrarily magnified by
increasing the size of the codes. These results suggest that using randomized
compiling can lead to a significant reduction in the resource overhead required
to achieve fault tolerance.
