Realization of a crosstalk-avoided quantum network node with dual-type qubits by the same ion species

TL;DR

This paper demonstrates a dual-type qubit scheme in a single ion species, enabling ion-photon entanglement with minimal crosstalk and long coherence times, advancing scalable trapped-ion quantum networks.

Contribution

It introduces a dual-type qubit scheme within the same ion species, simplifying control and reducing crosstalk in quantum network nodes.

Findings

Ion-photon entanglement achieved in hundreds of milliseconds.

Minimal crosstalk observed on nearby qubits.

Coherence time of the crosstalk-affected qubit exceeds seconds.

Abstract

Generating ion-photon entanglement is a crucial step for scalable trapped-ion quantum networks. To avoid the crosstalk on memory qubits carrying quantum information, it is common to use a different ion species for ion-photon entanglement generation such that the scattered photons are far off-resonant for the memory qubits. However, such a dual-species scheme requires elaborate control of the portion and the location of different ion species, and can be subject to inefficient sympathetic cooling. Here we demonstrate a trapped-ion quantum network node in the dual-type qubit scheme where two types of qubits are encoded in the $S$ and $F$ hyperfine structure levels of ${}^{171}\mathrm{Yb}^+$ ions. We generate ion photon entanglement for the $S$-qubit in a typical timescale of hundreds of milliseconds, and verify its small crosstalk on a nearby $F$-qubit with coherence time above seconds. Our work demonstrates an enabling function of the dual-type qubit scheme for scalable quantum networks.