Feynman diagrams versus Fermi-gas Feynman emulator

TL;DR

This paper demonstrates that a series of Feynman diagrams can be accurately resummed in a non-perturbative regime using Bold Diagrammatic Monte Carlo, validated by experiments on ultra-cold fermionic gases, advancing understanding of strongly interacting fermions.

Contribution

The paper introduces and validates a non-perturbative resummation method for Feynman diagrams using BDMC, confirmed by ultra-cold atom experiments on the unitary Fermi gas.

Findings

Excellent agreement between BDMC calculations and experimental measurements.

Resummation of Feynman diagrams is controllable in strongly correlated regimes.

Method opens new avenues for solving complex many-body problems.

Abstract

Precise understanding of strongly interacting fermions, from electrons in modern materials to nuclear matter, presents a major goal in modern physics. However, the theoretical description of interacting Fermi systems is usually plagued by the intricate quantum statistics at play. Here we present a cross-validation between a new theoretical approach, Bold Diagrammatic Monte Carlo (BDMC), and precision experiments on ultra-cold atoms. Specifically, we compute and measure with unprecedented accuracy the normal-state equation of state of the unitary gas, a prototypical example of a strongly correlated fermionic system. Excellent agreement demonstrates that a series of Feynman diagrams can be controllably resummed in a non-perturbative regime using BDMC. This opens the door to the solution of some of the most challenging problems across many areas of physics.