Super-Tonks-Girardeau gas of spin-1/2 interacting fermions

TL;DR

This paper demonstrates the theoretical possibility of creating a stable excited state, called the super-Tonks-Girardeau gas, of spin-1/ick interacting fermions in one dimension, analogous to a known bosonic state, and suggests experimental detection methods.

Contribution

It introduces a method to realize a fermionic super-Tonks-Girardeau state via a sudden interaction switch, extending the concept from bosons to fermions with exact solutions.

Findings

Stable excited fermionic state can be achieved without pairing.

The frequency of the breathing mode varies with interaction strength.

The state is an exact analog of the bosonic super-Tonks-Girardeau state.

Abstract

Fermi gases confined in tight one-dimensional waveguides form two-particle bound states of atoms in the presence of a strongly attractive interaction. Based on the exact solution of the one-dimensional spin-1/2 interacting Fermi gas, we demonstrate that a stable excited state with no pairing between attractive fermionic atoms can be realized by a sudden switch of interaction from strongly repulsive regime to the strongly attractive regime. Such a state is an exact fermionic analog of the experimentally observed super-Tonks-Girardeau state of bosonic Cesium atoms [Science 325, 1224 (2009)] and should be possible to be observed by the experiment. The frequency of lowest breathing mode of the fermionic super-Tonks-Girardeau gas is calculated as a function of the interaction strength, which could be used as a detectable signature for the experimental observation.