Coherent control of a nuclear spin via interactions with a rare-earth ion in the solid-state

TL;DR

This paper demonstrates coherent control of a nuclear spin coupled to an Er$^{3+}$ ion in solid-state, enabling long-lived quantum registers for quantum communication.

Contribution

It shows the first coherent coupling and control of a nuclear spin via an Er$^{3+}$ electron spin in solid-state, with potential for quantum repeater applications.

Findings

Nuclear spin coherence time exceeds electron spin coherence time by orders of magnitude.

Successful implementation of one- and two-qubit gate operations using dynamical decoupling.

Long-lived nuclear spins can be integrated with telecom emitters for quantum networks.

Abstract

Individually addressed Er$^{3+}$ ions in solid-state hosts are promising resources for quantum repeaters, because of their direct emission in the telecom band and compatibility with silicon photonic devices. While the Er$^{3+}$ electron spin provides a spin-photon interface, ancilla nuclear spins could enable multi-qubit registers with longer storage times. In this work, we demonstrate coherent coupling between the electron spin of a single Er$^{3+}$ ion and a single $I=1/2$ nuclear spin in the solid-state host crystal, which is a fortuitously located proton ($^1$H). We control the nuclear spin using dynamical decoupling sequences applied to the electron spin, implementing one- and two-qubit gate operations. Crucially, the nuclear spin coherence time exceeds the electron coherence time by several orders of magnitude, because of its smaller magnetic moment. These results provide a path towards combining long-lived nuclear spin quantum registers with telecom-wavelength emitters for long-distance quantum repeaters.