Holographic Interfaces in N=4 SYM: Janus and J-folds

We find the holographic dual to the three classes of superconformal Janus interfaces in $\mathcal{N}=4$ SYM that preserve three-dimensional $\mathcal{N}=4$, $\mathcal{N}=2$, and $\mathcal{N}=1$ supersymmetry. The solutions are constructed in five-dimensional SO(6) maximal gauged supergravity and are then uplifted to type IIB supergravity. Corresponding to each of the three classes of Janus solutions, there are also AdS${}_4\times S^1\times S^5$ J-fold backgrounds. These J-folds have a non-trivial SL$(2,\mathbb{Z})$ monodromy for the axio-dilaton on the $S^1$ and are dual to three-dimensional superconformal field theories.