Harmonic Superfields in $\mathcal N=4$ Supersymmetric Quantum Mechanics

This is a brief survey of applications of the harmonic superspace methods to the models of $\mathcal N=4$ supersymmetric quantum mechanics (SQM). The main focus is on a recent progress in constructing SQM models with couplings to the background non-Abelian gauge fields. Besides reviewing and systemizing the relevant results, we present some new examples and make clarifying comments.