Macroscopic Coulomb blockade in large Josephson junction arrays

TL;DR

This paper theoretically analyzes transport in large Josephson junction arrays, revealing a macroscopic Coulomb blockade effect that depends on array size and temperature, leading to superinsulating behavior at low temperatures.

Contribution

It introduces a theoretical framework for understanding macroscopic Coulomb blockade in large JJAs, highlighting size-dependent gaps and superinsulating states.

Findings

Coulomb gap grows linearly with 1D array size

Logarithmic growth of Coulomb gap in 2D arrays

Identification of superinsulating state at low temperatures

Abstract

We investigate theoretically transport properties of one- and two-dimensional regular Josephson junction arrays (JJAs) in an insulating state. We derive the low-temperature current-voltage characteristics for the current mediated by the Cooper pair transfer across the system. In the case where the screening length associated with the capacitance of the islands to the ground is much larger than the island's size, we find that transport is governed by the macroscopic Coulomb blockade effect with the gap well exceeding a single island charging energy. In the limit when the screening length is much larger than the linear size of the array, the gap establishes the dependence on the array size, namely, the Coulomb gap grows linearly with the system size in 1D and grows as logarithm of the system size in the two-dimensional array. We find two transport regimes: At moderate temperatures, above the BKT-like charge binding-unbinding transition the low bias transport is thermally activated, the activation energy being equal to the Coulomb blockade energy. At low temperatures, below the binding-unbinding transition, a JJA falls into a superinsulating state with the resistance exhibiting a double-exponential temperature dependence.