Coherent spin control of a nanocavity-enhanced qubit in diamond.

Luozhou Li,Dirk Englund,Edward H Chen,Jacob Mower,Mircea Cotlet,Ming Lu,Michael Walsh,Igal Bayn,Daniel J Twitchen,Jordan Goldstein,Matthew L Markham,Ophir Gaathon,Matthew E Trusheim,Tim Schröder

doi:10.1038/ncomms7173

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 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 nitrogen-vacancy memories, but scaling to larger networks requires more efficient spin-photon interfaces such as optical resonators. Here we report such nitrogen-vacancy-nanocavity systems in the strong Purcell regime with optical quality factors approaching 10,000 and electron spin coherence times exceeding 200 μs 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.

Highlights

A central aim of quantum information processing is the efficient entanglement of multiple stationary quantum memories via photons
The diamond was fabricated by microwave (MW) plasmaassisted chemical vapour deposition (CVD), polished to 5 mm thickness and thinned to B200 nm using a combination of chlorine- and oxygen-reactive ion etching (Methods)
NV-nanocavity system B lies in the strong Purcell regime with b 1⁄4 0.54, which would lead to a B800-fold increase in entanglement generation rates between two distant NVs compared with present schemes without cavity enhancement, assuming the same collection efficiency as in previously reported experiments[20] (Supplementary Note 4)

Summary

Introduction

A central aim of quantum information processing is the efficient entanglement of multiple stationary quantum memories via photons. Quantum entanglement and teleportation have been shown between two nitrogen-vacancy memories, but scaling to larger networks requires more efficient spin-photon interfaces such as optical resonators. We report such nitrogen-vacancy-nanocavity systems in the strong Purcell regime with optical quality factors approaching 10,000 and electron spin coherence times exceeding 200 ms 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. No spin coherence measurements have been reported on single-crystal diamond cavities, leaving unverified the potential of NV-cavity systems as quantum memories

Methods

Results

Conclusion