Theory of coherent quantum phase-slips in Josephson junction chains with periodic spatial modulations

TL;DR

This paper develops a theoretical framework for understanding how periodic spatial modulations in Josephson junction chains influence coherent quantum phase-slips, which are crucial for quantum degeneracy lifting.

Contribution

It introduces a model linking spatial inhomogeneities to phase-slip amplitudes, extending understanding of quantum effects in modulated Josephson junction systems.

Findings

Quantum phase-slip amplitude depends on normal mode structure.

Periodic modulations alter the phase-slip amplitude.

Analysis provides insights into inhomogeneity effects on quantum coherence.

Abstract

We study coherent quantum phase-slips which lift the ground state degeneracy in a Josephson junction ring, pierced by a magnetic flux of the magnitude equal to half of a flux quantum. The quantum phase-slip amplitude is sensitive to the normal mode structure of superconducting phase oscillations in the ring (Mooij-Sch\"on modes). These, in turn, are affected by spatial inhomogeneities in the ring. We analyze the case of weak periodic modulations of the system parameters and calculate the corresponding modification of the quantum phase-slip amplitude.