Quantum Phase Transitions and Persistent Currents in Josephson-Junction Ladders

TL;DR

This paper investigates quantum phase transitions and persistent currents in coupled Josephson-junction arrays, emphasizing exciton-like pairs' roles under various external conditions using advanced numerical methods.

Contribution

It introduces a detailed numerical analysis of exciton effects and persistent currents in Josephson-junction ladders across different external parameters.

Findings

Identification of exciton-like pairs' influence on phase transitions

Quantitative analysis of persistent currents under varying flux and gate charges

Correlation functions revealing pairing mechanisms in the system

Abstract

In this work we study quantum phase transitions and persistent currents in capacitively coupled one-dimensional Josephson-junction arrays. We will focus particularly on the roles of exciton-like pairs in the strong coupling limit in the presence of external gate charges and magnetic fluxes. We use the numerical density-matrix renormalization group method for the study in the full range of values of gate charge and magnetic flux. To clarify the various effects, we report the pair correlation functions and the exciton densities as welll as the persistent current.