One-Dimensional Quantum Liquids: Beyond the Luttinger Liquid Paradigm

TL;DR

This paper reviews recent advances in understanding one-dimensional quantum fluids beyond the traditional Luttinger liquid paradigm, emphasizing the role of dispersion nonlinearity and new theoretical methods for analyzing dynamic correlations and transport.

Contribution

It introduces novel theoretical approaches that extend the Luttinger liquid framework to include nonlinear dispersion effects in 1D quantum systems.

Findings

Dispersion nonlinearity causes finite particle lifetimes.

New methods unify various 1D quantum fluid models.

Impact on transport properties at finite temperatures.

Abstract

For many years, the Luttinger liquid theory has served as a useful paradigm for the description of one-dimensional (1D) quantum fluids in the limit of low energies. This theory is based on a linearization of the dispersion relation of the particles constituting the fluid. We review the recent progress in understanding 1D quantum fluids beyond the low-energy limit, where the nonlinearity of the dispersion relation becomes essential. The novel methods which have been developed to tackle such systems combine phenomenology built on the ideas of the Fermi edge singularity and the Fermi liquid theory, perturbation theory in the interaction strength, and a new way of treating finite-size integrable models. These methods can be applied to a wide variety of 1D fluids, from 1D spin liquids to electrons in quantum wires to cold atoms confined to a 1D trap. We review existing results for various dynamic correlation functions, in particular the density structure factor and the spectral function. Moreover, we show how a dispersion nonlinearity leads to finite particle lifetimes, and discuss its impact on the transport properties of 1D systems at finite temperatures. The conventional Luttinger liquid theory is a special limit of the new theory, and we explain the relation between the two.