Realizing coherently convertible dual-type qubits with the same ion species

TL;DR

This paper demonstrates a method to implement two types of coherently-convertible qubits within the same ion species, simplifying quantum computing architectures and reducing experimental complexity.

Contribution

It introduces a novel approach to realize dual-type qubits in a single ion species with high-fidelity conversion and minimal crosstalk, advancing scalable quantum computing.

Findings

Achieved fast, high-fidelity conversion between qubit types

Crosstalk errors below 0.03%, below fault-tolerance threshold

Demonstrated feasibility of same-species dual qubits for quantum computing

Abstract

Trapped ions constitute one of the most promising systems for implementing quantum computing and networking. For large-scale ion-trap-based quantum computers and networks, it is critical to have two types of qubits, one for computation and storage, while the other for auxiliary operations like runtime qubit detection, sympathetic cooling, and repetitive entanglement generation through photon links. Dual-type qubits have previously been realized in hybrid systems using two ion species, which, however, introduces significant experimental challenges for laser setup, gate operations as well as the control of the fraction and positioning of each qubit type within an ion crystal. Here we solve these problems by implementing two coherently-convertible qubit types using the same ion species. We encode the qubits into two pairs of clock states of the 171Yb+ ions, and achieve fast and high-fidelity conversion between the two types using narrow-band lasers. We further demonstrate that operations on one qubit type, including sympathetic laser cooling, gates and qubit detection, have crosstalk errors less than 0.03% on the other type, well below the error threshold for fault-tolerant quantum computing. Our work showcases the feasibility and advantages of using coherently convertible dual-type qubits with the same ion species for future large-scale quantum computing and networking.