High-fidelity two-qubit quantum logic gates in a trapped-ion chain using axial motional modes

TL;DR

This paper demonstrates high-fidelity two-qubit gates in a 5-ion trapped calcium chain using axial motional modes, achieving over 99% fidelity for adjacent pairs and over 98% for arbitrary pairs, advancing scalable quantum computing.

Contribution

The work achieves over 99% fidelity in two-qubit gates in a 5-ion chain using axial modes, surpassing previous fidelities and addressing key error sources.

Findings

Fidelities exceeding 99% for adjacent pairs

Over 98% fidelity for arbitrary pairs

Improved scalability for ion-trap quantum processors

Abstract

Trapped-ion systems are one of the leading platforms for quantum information processing, where a key challenge is to scale up system size while maintaining high-fidelity two-qubit operations. A promising approach is to build high-performance modules interconnected via strong coupling. In particular, axial motional modes provide a feasible means of coupling short ion chains. However, previous implementations of fully connected 5-ion modules based on axial modes have been limited to fidelities of $96.6-98.0\%$. Here, we demonstrate two-qubit quantum logic gates in a 5-ion $^{40}$Ca$^{+}$ chain using axial modes, achieving fidelities exceeding $99\%$ for adjacent pairs and over $98\%$ for arbitrary pairs by carefully tackling dominant error sources. Our results are beneficial to the development of scalable ion-trap quantum processors, quantum simulation and quantum-enhanced metrology.