Multipolar Fermi-surface deformation in a Rydberg-dressed Fermi gas with long-range anisotropic interactions

TL;DR

This paper theoretically investigates how anisotropic, long-range interactions in a Rydberg-dressed Fermi gas deform its Fermi surface into complex shapes, influencing pairing and potentially enabling unconventional superconductivity.

Contribution

It introduces a detailed analysis of Fermi surface deformation due to anisotropic Rydberg-dressed interactions and explores the emergence of high angular momentum Cooper pairing.

Findings

Fermi surface can deform into ellipsoids or multipolar shapes depending on interaction parameters.

Large orbital angular momentum pairing states (p, f, h waves) can form around the deformed Fermi surface.

Rydberg dressing enables exploration of unconventional Fermi gases and multiwave superconductivity.

Abstract

We study theoretically the deformation of the Fermi surface (FS) of a three-dimensional gas of Rydberg-dressed $^6$Li atoms. The laser dressing to high-lying Rydberg $D$ states results in angle-dependent soft-core-shaped interactions whose anisotropy is described by multiple spherical harmonics. We show that this can drastically modify the shape of the FS and that its deformation depends on the interplay between the Fermi momentum $k_F$ and the reciprocal momentum $\bar{k}$ corresponding to the characteristic soft-core radius of the dressing-induced potential. When $k_F< \bar{k}$, the dressed interaction stretches a spherical FS into an ellipsoid. When $k_F\gtrsim \bar{k}$, complex deformations are encountered which exhibit multipolar characteristics. We analyze the formation of Cooper pairs around the deformed FS and show that they occupy large orbital angular momentum states ($p$, $f$, and $h$ wave) coherently. Our study demonstrates that Rydberg dressing to high angular momentum states may pave a route toward the investigation of unconventional Fermi gases and multiwave superconductivity.