Fermi-Polaron: Diagrammatic Monte Carlo for Divergent Sign-Alternating Series

Understand

Diagrammatic Monte Carlo approach is applied to a problem of a single spin-down fermion resonantly interacting with the sea of ideal spin-up fermions.

• On one hand, we develop a generic, sign-problem tolerant, method of exact numerical solution of polaron-type models.
• On the other hand, our solution is important for understanding the phase diagram and properties of the BCS-BEC crossover in the strongly imbalanced regime.
• This is the first, and possibly characteristic, example of how the Monte Carlo approach can be applied to a divergent sign-alternating diagrammatic series.