  We study the addition of quantum fermionic impurities to the N=6
supersymmetric Chern-Simons-matter theories in 2+1 spacetime dimensions. The
impurities are introduced by means of Wilson loops in the antisymmetric
representation of the gauge group. In a holographic setup, the system is
represented by considering D6-branes probing the AdS_4 x CP^3 background of
type IIA supergravity. We study the thermodynamic properties of the system and
show how a Kondo lattice model with holographic dimers can be constructed. By
computing the Kaluza-Klein fluctuation modes of the probe brane we determine
the complete spectrum of dimensions of the impurity operators. A very rich
structure is found, depending both on the Kaluza-Klein quantum numbers and on
the filling fraction of the impurities.
