Review of Decoherence‐Free Subspaces, Noiseless Subsystems, and Dynamical Decoupling
Daniel A. Lidar · Advances in chemical physics · 2014
This chapter provides an introduction to the theory of decoherence-free subspaces (DFSs), noiseless subsystems (NSs), and dynamical decoupling (DD) – the key tools for decoherence mitigation strategies. The second and third sections of the chapter discuss decoherence-free subspaces, and define and analyze the collective dephasing model and explain how to combine the corresponding DFS encoding with universal quantum computation. The next section considers the same problem in the context of the more general collective decoherence model. The fifth section analyzes NSs, a key generalization of DFSs. The subsequent section defines DD by analyzing the protection of a single qubit against pure dephasing and against general decoherence. The seventh section discusses DD as a symmetrization procedure; the combining of DD with DFS is discussed in the eighth section. The penultimate section addresses concatenated dynamical decoupling (CDD). In the final section, DD is linked to the representation theory ideas underlying NSs theory.