Coherent effects contribution to a fast gate fidelity in ion quantum computer

TL;DR

This paper investigates how coherent effects influence the fidelity of fast non-adiabatic quantum gates in ion traps, emphasizing the importance of accounting for these effects to improve multi-qubit quantum computing scalability.

Contribution

It provides an analytical and numerical analysis of coherence effects in SDK-based gates, highlighting their impact on gate fidelity and offering models for different trap configurations.

Findings

Coherent effects significantly affect gate fidelity.

Error from SDKs impacts overall gate performance.

Fidelity depends on laser power stability.

Abstract

Trapped ions are one of the most promising platforms for quantum computing due to the longest qubit coherence times and the highest gate fidelities. However, scaling the number of ions (qubits) in a linear Coulomb crystal is the key difficulty on the way to multi-qubit systems. One of the promising pathways to scale the number of qubits is to implement the pulsed non-adiabatic gates based on the sequence of State Dependent Kicks (SDKs). We have analytically and numerically studied the influence of coherent effects in the SDK sequence and, correspondingly, have deduced the influence of the individual SDK error on the net gate fidelity. We have shown that the coherence effects significantly impact the fidelity of non-adiabatic gates and must be taken into the account. As practical examples, we have developed a numerical model for full simulation of coherence effects using a linear ion microtrap array and a 2D microtrap array. We have also studied the dependency of the gate fidelity on the laser power fluctuations.