Quantum phase slip phenomenon in ultra-narrow superconducting nanorings

TL;DR

This paper investigates how quantum fluctuations in ultra-narrow superconducting nanorings suppress persistent currents, revealing fundamental impacts on superconductivity at the nanoscale and implications for nanoelectronic devices.

Contribution

It demonstrates the role of quantum phase slips in suppressing persistent currents in superconducting nanorings, highlighting a new quantum fluctuation effect on macroscopic coherence.

Findings

Quantum fluctuations suppress persistent currents in nanorings.

The current-phase relation is significantly altered by quantum phase slips.

The phenomenon impacts the fundamental understanding of superconductivity at the nanoscale.

Abstract

The smaller the system, typically - the higher is the impact of fluctuations. In narrow superconducting wires sufficiently close to the critical temperature Tc thermal fluctuations are responsible for the experimentally observable finite resistance. Quite recently it became possible to fabricate sub-10 nm superconducting structures, where the finite resistivity was reported within the whole range of experimentally obtainable temperatures. The observation has been associated with quantum fluctuations capable to quench zero resistivity in superconducting nanowires even at temperatures T-->0. Here we demonstrate that in tiny superconducting nanorings the same phenomenon is responsible for suppression of another basic attribute of superconductivity - persistent currents - dramatically affecting their magnitude, the period and the shape of the current-phase relation. The effect is of fundamental importance demonstrating the impact of quantum fluctuations on the ground state of a macroscopically coherent system, and should be taken into consideration in various nanoelectronic applications.