Decision Diagram Internals

QDD represents quantum states and operators with decision diagrams. The central C++ types are declared in include/dd.h and exposed to Python through qdd/bindings.cpp.

The public documentation should explain stable concepts:

• vector and matrix edges

• node identity and sharing

• edge weights

• garbage collection thresholds

• measurement and state collapse

Implementation comments should focus on invariants and non-obvious algorithmic choices rather than repeating each line of code.