Super Tonks-Girardeau state in an attractive one-dimensional dipolar gas

TL;DR

This paper investigates the metastable super Tonks-Girardeau state in an attractive 1D dipolar gas, revealing its properties and stability through theoretical analysis and Monte Carlo simulations.

Contribution

It introduces the existence and properties of a metastable super Tonks-Girardeau state in an attractive dipolar gas, extending understanding of 1D quantum gases with dipolar interactions.

Findings

The state is metastable as nd^2 approaches zero.

Wave function dynamics indicate near-stability after sudden dipole rotation.

Monte Carlo simulations accurately evaluate salient properties.

Abstract

The ground state of a one-dimensional (1D) quantum gas of dipoles oriented perpendicular to the longitudinal axis, with a strong 1/x^3 repulsive potential, is studied at low 1D densities $n$. Near contact the dependence of the many-body wave function on the separation x_{jl} of two particles reduces to a two-body wave function \Psi_{rel}(x_{jl}). Immediately after a sudden rotation of the dipoles so that they are parallel to the longitudinal axis, this wave function will still be that of the repulsive potential, but since the potential is now that of the attractive potential, it will not be stationary. It is shown that as nd^2 -> 0 the rate of change of this wave function approaches zero. It follows that for small values of nd^2, this state is metastable and is an analog of the super Tonks-Girardeau state of bosons with a strong zero-range attraction. The dipolar system is equivalent to a spinor Fermi gas with spin $z$ components \sigma_{\uparrow}=\perp (perpendicular to the longitudinal axis) and \sigma_{\downarrow}=|| (parallel to the longitudinal axis). A Fermi-Fermi mapping from spinor to spinless Fermi gas followed by the standard 1960 Fermi-Bose mapping reduces the Fermi system to a Bose gas. Potential experiments realizing the sudden spin rotation with ultracold dipolar gases are discussed, and a few salient properties of these states are accurately evaluated by a Monte Carlo method.