Quantum Zeno effect in the Cooper-pair transport through a double-island Josephson system

TL;DR

This paper investigates how the quantum Zeno effect influences Cooper-pair transport in a double-island Josephson system, revealing how dissipation and noise levels affect charge transport and resonant features.

Contribution

It provides a comprehensive analysis of the quantum Zeno effect in a double-island Josephson system, including the impact of dissipation and noise on transport properties.

Findings

High noise levels induce the quantum Zeno effect, slowing transport.

Analysis explains features of I-V curves, including resonant peaks.

Coherent superpositions of charge states are crucial at low bias.

Abstract

Motivated by recent experiments, we analyze transport of Cooper pairs through a double-island Josephson qubit. At low bias in a certain range of gate voltages coherent superpositions of charge states play a crucial role. Analysis of the evolution of the density matrix allows us to cover a wide range of parameters, incl. situations with degenerate levels, when dissipation strongly affects the coherent eigenstates. At high noise levels the so-called Zeno effect can be observed, which slows down the transport. Our analysis explains certain features of the I-V curves, in particular the visibility and shape of resonant peaks and lines.