Effect of zero point phase fluctuations on Josephson tunneling

TL;DR

This paper investigates how zero point phase fluctuations alter the Josephson effect, revealing a finite voltage peak replacing supercurrent at zero voltage, with analysis connecting Coulomb blockade and quantum tunneling regimes.

Contribution

It introduces a theoretical framework describing the impact of phase fluctuations on Josephson tunneling, linking different physical regimes and providing analytical expressions for peak positions.

Findings

Zero temperature peak determined by two complementary expansions.

Peak positions and critical current suppression analyzed.

Results connect Coulomb blockade and quantum tunneling regimes.

Abstract

In the presence of phase fluctuations the dc Josephson effect is modified and the supercurrent at zero voltage is replaced by a peak at small but finite voltages. It is shown that at zero temperature this peak is determined by two complementary expansions of finite radius of convergence. The leading order expressions are related to results known from the regimes of Coulomb blockade and of macroscopic quantum tunneling. The peak positions and the suppression of the critical current by quantum fluctuations are discussed.