# Scalable global entangling gates on arbitrary ion qubits

## TL;DR

This paper presents a scalable method to implement global entangling gates on multiple ion qubits, enabling efficient quantum circuit construction and demonstrating high-fidelity multi-qubit entanglement in trapped-ion systems.

## Contribution

It introduces a novel scheme for global entangling gates on ion qubits using multiple motional modes and fully-independent control, with experimental validation.

## Key findings

- Successfully prepared GHZ states with over 93.4% fidelity
- Demonstrated genuine multi-partite entanglement up to four qubits
- Achieved scalable global entangling gates in a trapped-ion system

## Abstract

A quantum algorithm can be decomposed into a sequence consisting of single qubit and 2-qubit entangling gates. To optimize the decomposition and achieve more efficient construction of the quantum circuit, we can replace multiple 2-qubit gates with a single global entangling gate. Here, we propose and implement a scalable scheme to realize the global entangling gates on multiple $\yb$ ion qubits by coupling to multiple motional modes through external fields. Such global gates require simultaneously decoupling of multiple motional modes and balancing of the coupling strengths for all the qubit-pairs at the gate time. To satisfy the complicated requirements, we develop a trapped-ion system with fully-independent control capability on each ion, and experimentally realize the global entangling gates. As examples, we utilize them to prepare the Greenberger-Horne-Zeilinger (GHZ) states in a single entangling operation, and successfully show the genuine multi-partite entanglements up to four qubits with the state fidelities over $93.4\%$.