Weak three-dimensional mediators of two-dimensional triplet pairing

TL;DR

This paper proposes a method to engineer effective interactions in mixed-dimensional cold atom systems, enabling the study of triplet pairing and related exotic quantum phases with potential experimental realization.

Contribution

It introduces a way to create tunable, symmetric density-density interactions in 2D fermions via 3D atomic species, facilitating triplet pairing.

Findings

Critical temperature for triplet pairing depends exponentially on interaction strength.

Effective interactions can be tuned by adjusting 3D species densities.

Analysis suggests stable triplet pairing phases are achievable under certain conditions.

Abstract

Recent experiments demonstrate the ability to construct cold atom mixtures with species selective optical lattices. This allows for the possibility of a mixed-dimension system, where one fermionic atomic species is confined to a two dimensional lattice, while another species is confined to a three dimensional lattice that contains the two-dimensional one. We show that by tuning the density of an arbitrary number of three-dimensional atomic species, we can engineer an arbitrary, rotationally-symmetric, density-density, effective interaction for the two-dimensional particles. This possibility allows for an effective interaction that favours triplet pairing for two-dimensional, $SU(2)$ symmetric particles. Using a functional renormalization-group analysis for the two-dimensional particles, we derive and numerically confirm that the critical temperature for triplet pairing depends exponentially on the effective interaction strength. We then analyse how the stability of this phase is affected by the particle densities and the fine tuning of interaction parameters. We conclude by briefly discussing experimental considerations and the potential to study triplet pairing physics, including Majorana fermions and spin textures, with cold atoms on optical lattices.