Finite-range effects in the two-dimensional repulsive Fermi polaron

TL;DR

This paper investigates the two-dimensional repulsive Fermi polaron using diffusion Monte Carlo simulations, emphasizing the importance of finite-range effects and establishing a universal regime that aligns with recent experimental results.

Contribution

It demonstrates that including the effective range alongside the scattering length is essential to accurately reproduce experimental observations of the Fermi polaron.

Findings

Finite-range effects are crucial for matching experimental data.

A universal regime exists governed by scattering length and effective range.

Quantum fluctuations significantly influence the polaron properties.

Abstract

We study the repulsive Fermi polaron in a two-component, two-dimensional system of fermionic atoms inspired by the results of a recent experiment with $^{173}$Yb atoms [N. Darkwah Oppong \textit{et al.}, Phys. Rev. Lett. \textbf{122}, 193604 (2019)]. We use the diffusion Monte Carlo method to report properties such as the polaron energy and the quasi-particle residue that have been measured in that experiment. To provide insight on the quasi-particle character of the problem, we also report results for the effective mass. We show that the effective range, together with the scattering length, is needed in order to reproduce the experimental results. Using different model potentials for the interaction between the Fermi sea and the impurity, we show that it is possible to establish a regime of universality, in terms of these two parameters, that includes the whole experimental regime. This illustrates the relevance of quantum fluctuations and beyond mean-field effects to correctly describe the Fermi polaron problem.