Superconducting single-charge transistor in a tunable dissipative environment

TL;DR

This paper investigates how a tunable dissipative environment affects the coherence and tunneling processes in a superconducting single-charge transistor, revealing a crossover between environment-assisted and environment-dominated regimes.

Contribution

It introduces a detailed model analyzing the impact of dissipation on Cooper pair tunneling, with predictions confirmed by experiments, and applies to Josephson junction qubits.

Findings

Identification of a crossover between two regimes affecting conductance

Confirmation of theoretical predictions through experiments

Insights into dissipation's role in qubit coherence

Abstract

We study a superconducting single-charge transistor, where the coherence of Cooper pair tunneling is destroyed by the coupling to a tunable dissipative environment. Sequential tunneling and cotunneling processes are analyzed to construct the shape of the conductance peaks and their dependence on the dissipation and temperature. Unexpected features are found due to a cross-over between two distinct regimes, one `environment-assisted' the other `environment-dominated'. Several of the predictions have been confirmed by recent experiments. The model and results apply also to the dynamics of Josephson junction quantum bits on a conducting ground plane, thus explaining the influence of dissipation on the coherence.