Unified Quantum Picture Bridges Moving and Fixed Impurities in Quantum Matter
Physicists at Heidelberg University report a unified theoretical framework that links the mobile-quasiparticle (Fermi polaron) and static-impurity (Anderson’s orthogonality catastrophe) descriptions of impurities in quantum many-body systems. The key insight is that even extremely heavy impurities exhibit tiny motions that create an energy gap, enabling quasiparticle formation and bridging polaronic and molecular states. The work offers a versatile description across dimensions and interactions and has direct relevance for experiments with ultracold gases, two-dimensional materials, and novel semiconductors; the findings were published in Physical Review Letters as “Mass-Gap Description of Heavy Impurities in Fermi Gases.”