The QM Superposition 2D program displays the time evolution of the two-dimensional position-space wave function using color to represent its phase. The default wave function is a two-state superposition in the x (nx = 1,2) and y dimension (ny = 3,4) state in an infinite square well. Additional states and other potential energy functions can be specified using the Display | Switch GUI menu item. QM Superposition 2D is one of 18 Open Source Physics programs that model time-dependent quantum mechanics using an energy eigenstate expansion. It is distributed as a ready-to-run (compiled) Java archive. Double clicking the qm_superposition_2d.jar file will run the program if Java is installed. Other programs provide additional visualizations. They can be found by searching ComPADRE for Open Source Physics, OSP, or Superposition.