Superconductor-insulator transition in capacitively coupled superconducting nanowires

TL;DR

This paper explores how capacitive coupling between ultrathin superconducting nanowires influences their superconductor-insulator phase transition, revealing that interactions and plasma modes affect the transition depending on neighboring wire parameters.

Contribution

It introduces coupled BKT-like RG equations showing that quantum phase slip interactions are modified by plasma modes in neighboring wires, affecting phase transitions.

Findings

Interaction between phase slips is modified by plasma modes.

Phase transition depends on neighboring wire parameters and mutual capacitance.

Properly tuned parameters can induce insulating behavior in nanowires.

Abstract

We investigate superconductor-insulator quantum phase transitions in ultrathin capacitively coupled superconducting nanowires with proliferating quantum phase slips. We derive a set of coupled Berezinskii-Kosterlitz-Thouless-like renormalization group equations demonstrating that interaction between quantum phase slips in one of the wires gets modified due to the effect of plasma modes propagating in another wire. As a result, the superconductor-insulator phase transition in each of the wires is controlled not only by its own parameters but also by those of the neighboring wire as well as by mutual capacitance. We argue that superconducting nanowires with properly chosen parameters may turn insulating once they are brought sufficiently close to each other.