Rudnick and Sarnak have conjectured that the L^2-mass of Laplacian eigenfunctions of a negatively curved surface should equidistribute in the large Laplacian eigenvalue limit. This is known as the quantum unique ergodicity conjecture. When this surface is the modular surface, these eigenfunctions are a type of automorphic form called Maass forms, and this conjecture is implied by nontrivial bounds for special values of certain Rankin-Selberg L-functions associated to these automorphic forms. I will discuss a generalisation of this conjecture involving the restriction to the modular surface of automorphic forms associated to quadratic number fields, and how progress towards this conjecture is dependent on nontrivial bounds for certain Rankin-Selberg L-functions. This is joint work with Jesse Thorner.