What kind of software is used for modelling quantum processor architectures? Not just simulate the output, but the one that is actually used in research.
Are you looking for something that simulates the actual hardware, or something that runs quantum circuits?
If you're looking for circuit simulation with the widest variety of possible operations, the closest thing we can do on a classical computer is Density Matrix simulation.
are two that I've used, but others are also out there.
If you actually want to simulate the physics happening on the hardware level, the question is very hardware specific.