Quantum Phase-Slip Junction Under Microwave Irradiation

TL;DR

This paper investigates the dynamics of quantum phase-slip junctions under microwave irradiation, analyzing how thermal and quantum fluctuations affect the observation of dual Shapiro steps, which are crucial for quantum current standards.

Contribution

It provides a theoretical study of fluctuation effects on dual Shapiro steps in QPSJs, highlighting environmental influences and energy ratios affecting their observability.

Findings

Fluctuations can significantly smear the I-V characteristic.

Environmental resistance and energy ratios govern fluctuation effects.

Results inform experimental efforts to observe dual Shapiro steps.

Abstract

We consider the dynamics of a quantum phase-slip junction (QPSJ) -- a dual Josephson junction -- connected to a microwave source with frequency $\omega_\textrm{mw}$. With respect to an ordinary Josephson junction, a QPSJ can sustain dual Shapiro steps, consisting of well-defined current plateaus at multiple integers of $ e \omega_\textrm{mw} / \pi$ in the current-voltage (I-V) characteristic. The experimental observation of these plateaus has been elusive up to now. We argue that thermal as well as quantum fluctuations can smear the I-V characteristic considerably. In order to understand these effects, we study a current-biased QPSJ under microwave irradiation and connected to an inductive and resistive environment. We find that the effect of these fluctuations are governed by the resistance of the environment and by the ratio of the phase-slip energy and the inductive energy. Our results are of interest for experiments aimed at the observation of dual Shapiro steps in QPSJ devices for the definition of a new quantum current standard.