New quantum phases in a one-dimensional Josephson array

TL;DR

This paper explores the phase diagram of a one-dimensional Josephson array, revealing new charge-ordered and Luttinger liquid phases near charge degeneracy points, with implications for Josephson current behavior.

Contribution

It identifies and characterizes new quantum phases in a 1D Josephson array near charge degeneracy, expanding understanding of correlated quantum states in such systems.

Findings

Discovery of charge density wave phase near degeneracy points

Identification of a repulsive Luttinger liquid phase

Predicted dependence of Josephson current on gate voltage

Abstract

We examine the phase diagram of an ordered one-dimensional Josephson array of small grains. The average grain charge in such a system can be tuned by means of gate voltage. At small grain-to-grain conductance, this system is strongly correlated because of the charge discreteness constraint (Coulomb blockade). At the gate voltages in the vicinity of the charge degeneracy points, we find new phases equivalent to a commensurate charge density wave and to a repulsive Luttinger liquid. The existence of these phases can be probed through a special dependence of the Josephson current on the gate voltage.