Engineering the localization transition in a Charge-Kondo circuit

TL;DR

This paper proposes a charge-Kondo circuit that exhibits a tunable localization transition, with experimental signatures like diverging charge susceptibility, advancing the simulation of strongly interacting quantum models.

Contribution

It introduces a novel circuit design realizing the Kondo effect with Luttinger-liquid interactions and demonstrates a controllable localization transition.

Findings

Localization transition with suppressed QPC transmission below critical value

Diverging charge susceptibility at transition

Entropy step indicating phase change

Abstract

Charge Kondo circuits consist of metallic islands connected by single-mode quantum point contacts (QPCs). The island's charging energy makes these circuits tunable quantum simulators of various strongly interacting models. Here we propose a circuit that realizes the Kondo effect with effective Luttinger-liquid interactions, and show that it undergoes a localization transition in which the QPC transmission is fully suppressed below a critical value. Experimental signatures include a diverging charge susceptibility and an entropy step. Our findings open a path toward realizing localization transitions in more exotic settings.