Derivation of the Ghost Gutzwiller Approximation from Quantum Embedding principles: the Ghost Density Matrix Embedding Theory

We outline the derivation of the Ghost Gutzwiller Approximation (gGA) from principles closely related to those in Density Matrix Embedding Theory (DMET). This derivation emphasizes the crucial role of ghost degrees of freedom and provides a conceptual connection between DMET and gGA. We also outline recent progress in exploiting the quantum-embedding algorithmic structure of this framework to reduce its computational cost.