Many-body/Materials covers concepts whose central question concerns interacting systems, collective phases of matter, material behavior, or the quantities used to characterize them. A paper or Concept stays here when quantum-information, machine-learning, or numerical tools are used to establish a physics or materials result rather than being the main contribution themselves.
Folder placement supplies one canonical navigation home. Cross-cutting relationships to quantum information, mathematics, or computational methods remain represented through page metadata and links.