Coherent spin control of a nanocavity-enhanced qubit in diamond

TL;DR

This paper demonstrates a nanocavity-enhanced NV center in diamond with high optical quality and long electron spin coherence, enabling efficient quantum memory and control for scalable quantum networks.

Contribution

It introduces a silicon hard-mask fabrication process for NV-nanocavity systems with high optical quality and extended spin coherence, integrated with on-chip microwave control.

Findings

Optical quality factors approaching 10,000 achieved.

Electron spin coherence times exceeding 200 microseconds.

Integrated on-chip microwave striplines for coherent spin control.

Abstract

A central aim of quantum information processing is the efficient entanglement of multiple stationary quantum memories via photons. Among solid-state systems, the nitrogen-vacancy (NV) centre in diamond has emerged as an excellent optically addressable memory with second-scale electron spin coherence times. Recently, quantum entanglement and teleportation have been shown between two NV-memories, but scaling to larger networks requires more efficient spin-photon interfaces such as optical resonators. Here, we demonstrate such NV-nanocavity systems with optical quality factors approaching 10,000 and electron spin coherence times exceeding 200 $\mu$s using a silicon hard-mask fabrication process. This spin-photon interface is integrated with on-chip microwave striplines for coherent spin control, providing an efficient quantum memory for quantum networks.