We predict and analyze {it radiation-induced quantum interference effect} in low-dimensional $n$-$p$ junctions. This phenomenon manifests itself by large oscillations of the photocurrent as a function of the gate voltage or the frequency of the radia
tion. The oscillations result from the quantum interference between two electron paths accompanied by resonant absorption of photons. They resemble Ramsey quantum beating and Stueckelberg oscillations well-known in atomic physics. The effect can be observed in one- and two-dimensional $n$-$p$ junctions based on nanowires, carbon nanotubes, monolayer or bilayer graphene nanoribbons.
