Quasi-Andreev reflection in inhomogeneous Luttinger liquids

TL;DR

This paper explores how charge excitations reflect in inhomogeneous Luttinger liquids, revealing quasi-Andreev reflection phenomena that mimic superconductor-normal metal interfaces and cause notable local electronic effects.

Contribution

It introduces the concept of quasi-Andreev reflection in Luttinger liquids with inhomogeneous interactions, highlighting proximity-like effects and their observable consequences.

Findings

Quasi-Andreev reflection causes local enhancement or suppression of superconducting fluctuations.

Significant modification of the local density of states is observed.

Proximity-like effects influence tunneling characteristics in inhomogeneous Luttinger liquids.

Abstract

Reflection of charge excitations at the step in the interaction strength in a Luttinger liquid can be of the Andreev type, even if the interactions are purely repulsive. The region with stronger repulsion plays the role of a normal metal in a normal-metal /superconductor junction, whereas the region with weaker repulsion plays the role of a superconductor. It is shown that this quasi-Andreev reflection leads to a number of proximity-like effects, including the local enhancement (suppression) of superconducting fluctuations on the quasi-normal (quasi-superconducting) side of the step, significant modification of the local density of states, as well as others. The observable consequences of these proximity effects are analyzed for the case of single- and two-particle tunneling from a normal-metal or superconducting tip into an inhomogeneous Luttinger-liquid wire.