The effect of fast noise on the fidelity of trapped-ions quantum gates

TL;DR

This paper investigates how fast phase noise at high frequencies impacts the fidelity of single and two-qubit gates in trapped-ion quantum computers, providing a simple estimation method for performance affected by noise spectral density.

Contribution

It introduces a unified approach to estimate gate performance under fast noise using a single parameter based on noise spectral density, applicable to trapped-ion and other qubit systems.

Findings

Fast noise significantly affects gate fidelities.

A simple parameter can predict performance degradation.

Results guide hardware design for improved quantum fidelity.

Abstract

High fidelity single and multi-qubit operations compose the backbone of quantum information processing. This fidelity is based on the ability to couple single- or two-qubit levels in an extremely coherent and precise manner. A necessary condition for coherent quantum evolution is a highly stable local oscillator driving these transitions. Here we study the effect of fast noise, that is noise at frequencies much higher than the local oscillator linewidth, on the fidelity of one- and two-qubit gates in a trapped-ion system. We analyze and measure the effect of fast noise on single qubit operations including resonant $\pi$ rotations and off-resonant sideband transitions . We further analyze the effect of fast phase noise on the Molmer-Sorensen two-qubit gate. We find a unified and simple way to estimate the performance of all of these operations through a single parameter given by the noise power spectral density at the qubit response frequency. While our analysis focuses on phase noise and on trapped-ion systems, it is relevant for other sources of fast noise as well as for other qubit systems in which spin-like qubits are coupled by a common bosonic field. Our analysis can help in guiding the deign of quantum hardware platforms and gates, improving their fidelity towards fault-tolerant quantum computing.