Sommerfeld Theory Colloquium, Condensed matter provides us deep insights into quantum physics.

Giving just two examples, wave-corpuscle duality manifests itself in

spectroscopy of strongly correlated systems as coexistence of itinerant

and atomic-like features, and graphene and other Dirac materials

provide a natural playground to study vacuum reconstruction, Klein

tunneling and other fundamental quantum relativistic phenomena.

Electron-photon interaction is the key tool to understand this rich

and nontrivial physics.