Loss in hybrid qubit-bus couplings and gates

TL;DR

This paper analyzes how dissipation affects hybrid qubit-bus quantum gates, proposing a new loss analysis method and demonstrating that high-fidelity operations are possible despite moderate dissipation.

Contribution

It introduces a novel approach to analyze and minimize loss effects in hybrid qubit-bus gates, including an iteration scheme that preserves the conditional phase.

Findings

High fidelity achievable with moderate dissipation

Effective loss analysis method for hybrid gates

Iteration scheme maintains conditional phase despite loss

Abstract

We provide a characterization and analysis of the effects of dissipation on oscillator assisted (qubus) quantum gates. The effects can be understood and minimized by looking at the dynamics of the signal coherence and its entanglement with the continuous variable probe. Adding loss in between successive interactions we obtain the effective quantum operations, providing a novel approach to loss analysis in such hybrid settings. We find that in the presence of moderate dissipation the gate can operate with a high fidelity. We also show how a simple iteration scheme leads to independent single qubit dephasing, while retaining the conditional phase operation regardless of the amount of loss incurred by the probe.