Boosted one dimensional superfluids on a lattice

TL;DR

This paper investigates how applying a boost to one-dimensional lattice fermion systems with attractive interactions can enhance superconducting correlations, contrary to higher-dimensional expectations, and can induce phase transitions like the Luther-Emery phase.

Contribution

It demonstrates that a boost can strengthen algebraic superconducting order and induce phase changes in 1D fermionic systems, revealing novel effects of momentum displacement.

Findings

Boost enhances superconducting correlations in 1D systems.

A boost can induce a Luther-Emery phase with charge and spin gaps.

Correlation functions decay more slowly under a boost.

Abstract

We study the effect of a boost (Fermi sea displaced by a finite momentum) on one dimensional systems of lattice fermions with short-ranged interactions. In the absence of a boost such systems with attractive interactions possess algebraic superconducting order. Motivated by physics in higher dimensions, one might naively expect a boost to weaken and ultimately destroy superconductivity. However, we show that for one dimensional systems the effect of the boost can be to strengthen the algebraic superconducting order by making correlation functions fall off more slowly with distance. This phenomenon can manifest in interesting ways, for example, a boost can produce a Luther- Emery phase in a system with both charge and spin gaps by engendering the destruction of the former.