Improved quantum error correction with randomized compiling

Optimizing fault-tolerance schemes has been a central goal in the field of quantum error correction. In this paper, 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) improve the fidelity of quantum circuits by converting coherent noise to an effective stochastic noise. Combined with quantum error correction schemes, they effectively reduce the number of features of the physical noise process that impact a code's performance. Of particular interest is the class of coherent errors, where RC has the maximum effect. For these errors, we show that RC can offer 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 massive reduction in the resource overhead required to achieve fault tolerance.