Experimental Realization of One Dimensional Helium

TL;DR

This paper reports the experimental realization of a one-dimensional quantum system using confined helium, demonstrating unique excitations and tunable interactions, advancing understanding of 1D quantum liquids beyond traditional models.

Contribution

It presents the first experimental observation of 1D helium behavior using nanoengineering, showing qualitative differences from higher-dimensional helium and enabling tunable quantum states.

Findings

Observed 1D helium excitations distinct from 3D and 2D superfluid helium.

Demonstrated tunability of the system from weakly interacting to strongly interacting regimes.

Analyzed excitations using Luttinger liquid theory and impurity models.

Abstract

The realization of experimental platforms exhibiting one dimensional (1D) quantum phenomena has been elusive, due to their inherent lack of stability, with a few notable exceptions including spin chains, carbon nanotubes and ultracold low-density gasses. The difficulty of such systems in exhibiting long range order is integral to their effective description in terms of the Tomonaga-Luttinger liquid theory. Recently, it has been proposed that bosonic superfluid 4He could realize a 1D quantum system beyond the Luttinger liquid paradigm. Here we describe an experimental observation of this behavior using nanoengineering by preplating a porous material with a noble gas to enhance dimensional reduction. The resulting excitations of the confined 4He are qualitatively different than 3D and 2D superfluid helium, and can be analyzed in terms of a mobile impurity in a Luttinger liquid allowing for the characterization of the emergent quantum liquid. The confined helium system offers the possibility of tuning via pressure - from weakly interacting, all the way to the super Tonks-Girardeau gas of strongly interacting hard-core particles.