Quantum phase diffusion in ac-driven superconducting atomic point contacts

TL;DR

This paper investigates how quantum fluctuations influence phase diffusion in ac-driven superconducting atomic point contacts, revealing that quantum effects cause resonance broadening beyond simple temperature effects.

Contribution

It extends the classical Smoluchowski equation to the quantum regime to analyze phase diffusion and Shapiro resonances in superconducting quantum points.

Findings

Quantum fluctuations cause resonance broadening beyond effective temperature explanations.

Numerical results show characteristic features of quantum effects on Shapiro resonances.

Quantum regime effects differ significantly from classical predictions.

Abstract

The impact of quantum fluctuations on the phase diffusion in resistively shunted superconducting quantum points subject to an external ac-voltage is studied. Based on an extension of the classical Smoluchowski equation to the quantum regime, numerical results for fractional and integer Shapiro resonances are investigated to reveal characteristic features of quantum effects. It is shown that typically in the quantum regime the broadening of resonances cannot be described simply by an effective temperature.