Universal Fermi gases in mixed dimensions

TL;DR

This paper explores universal properties of mixed-dimensional two-species Fermi gases, revealing stable regimes and calculating key many-body phase diagram quantities, with potential for realizing scale-invariant systems.

Contribution

It introduces the concept of mixed-dimensional Fermi gases with tunable interspecies interactions and identifies stability conditions avoiding Efimov effects.

Findings

Stable regimes identified for specific mass ratios.

Calculated key quantities in the many-body phase diagram.

Elucidated other scale-invariant systems with short-range interactions.

Abstract

We investigate a two-species Fermi gas in which one species is confined in a two-dimensional plane (2D) or one-dimensional line (1D) while the other is free in the three-dimensional space (3D). We discuss the realization of such a system with the interspecies interaction tuned to resonance. When the mass ratio is in the range 0.0351<m_2D/m_3D<6.35 for the 2D-3D mixture or 0.00646<m_1D/m_3D<2.06 for the 1D-3D mixture, the resulting system is stable against the Efimov effect and has universal properties. We calculate key quantities in the many-body phase diagram. Other possible scale-invariant systems with short-range few-body interactions are also elucidated.