Comment on "Novel Superfluidity in a Trapped Gas of Fermi Atoms with Repulsive Interaction Loaded on an Optical Lattice"

TL;DR

This paper critiques a previous claim that superfluidity occurs in a trapped Fermi gas with repulsive interactions, arguing that the observed effects are not indicative of superfluidity.

Contribution

It provides a critical analysis showing that the effects observed are not related to superfluidity, challenging prior interpretations.

Findings

The observed effects are not due to superfluidity.

Negative binding energy does not imply superfluid phase.

Large singlet weight is not conclusive evidence of superfluidity.

Abstract

In a recent letter Machida et al. [Phys. Rev. Lett. 93, 200402 (2004)] concluded that in a trapped gas of fermions with repulsive interactions a superfluid phase appears around the Mott-insulator at the center of the trap. They base their conclusion on a negative binding energy, and a large weight for a singlet formed by particles located at opposite sides of the Mott-insulator. We show here that the observed effects are not related to superfluidity.