Josephson decoupling phase in inhomoheneous arrays of superconducting quantum dots

TL;DR

This paper investigates the quantum phase behavior of inhomogeneous and homogeneous arrays of superconducting quantum dots, revealing a Josephson decoupling phase at half filling caused by Josephson coupling fluctuations.

Contribution

It demonstrates the existence of a Josephson decoupling phase only at half filling in inhomogeneous SQD arrays due to Josephson coupling fluctuations.

Findings

Josephson decoupling phase occurs only at half filling in inhomogeneous arrays.

Superconductivity vanishes in JD phase without Coulomb blockade.

Coulomb interactions induce a gapped Coulomb blockade phase.

Abstract

We present a study of quantum phase analysis of inhomogeneous and homogeneous arrays of superconducting quantum dots (SQD). We observe the existance of Josephson decouple (JD) phase only at the half filling for inhomogeneous array of SQD due to the fluctuation of Josephson couplings over the sites at half filling. In JD phase superconductivity disappears even in the absence of Coulomb blockade phase. We also observe that fluctuation of on-site Coulomb charging energy produces the relevant coupling term that yields Coulomb blockade gapped phase. The presence of nearest-neighbor and next-nearest-neighbor Coulomb interaction yields the same physics for inhomogeneous and homogeneous SQD.