We can regard quarkonium in a medium as an open quantum system interacting with an environment. This formalism allows us to study how heavy quark dynamics is affected by the medium, keeping track of the quantum features needed to understand bound state formation. Within this framework, the evolution of quarkonium is given by the so-called master equation. Using a Monte Carlo method, called the quantum trajectories method, we have been able to efficiently simulate quarkonium's master equation in the limit where the medium sees the bound state as a small color dipole. In this talk, I will discuss two recent developments in this approach. First, I will talk about the ongoing efforts to apply the quantum trajectories method without assuming a small color dipole. Additionally, I will also discuss how to apply the formalism to study the X(3872) state in heavy-ion collisions, assuming that it is a tetraquark.
