Robust all-optical single-shot readout of nitrogen-vacancy centers in diamond

Dominik M Irber,Tobias Lühmann,Michael Kieschnick,Francesco Poggiali,Jan Meijer,Fazhan Shi,Damian Kwiatkowski,Fei Kong,Jiangfeng Du,Friedemann Reinhard

doi:10.1038/s41467-020-20755-3

Abstract

High-fidelity projective readout of a qubit’s state in a single experimental repetition is a prerequisite for various quantum protocols of sensing and computing. Achieving single-shot readout is challenging for solid-state qubits. For Nitrogen-Vacancy (NV) centers in diamond, it has been realized using nuclear memories or resonant excitation at cryogenic temperature. All of these existing approaches have stringent experimental demands. In particular, they require a high efficiency of photon collection, such as immersion optics or all-diamond micro-optics. For some of the most relevant applications, such as shallow implanted NV centers in a cryogenic environment, these tools are unavailable. Here we demonstrate an all-optical spin readout scheme that achieves single-shot fidelity even if photon collection is poor (delivering less than 103 clicks/second). The scheme is based on spin-dependent resonant excitation at cryogenic temperature combined with spin-to-charge conversion, mapping the fragile electron spin states to the stable charge states. We prove this technique to work on shallow implanted NV centers, as they are required for sensing and scalable NV-based quantum registers.

Highlights

High-fidelity projective readout of a qubit’s state in a single experimental repetition is a prerequisite for various quantum protocols of sensing and computing
We have pushed the fidelity of spin-to-charge conversion (SCC) into the single-shot regime, by combining it with resonant excitation at cryogenic temperature
We achieve a single-shot signal-to-noise ratio (SNR) of 3.5 and 0.99 on a deep and shallow center respectively, which provides a speedup in the range of 103 over standard readout and a speedup of ~20 over the resonant excitation readout method[7]

Summary

Introduction

High-fidelity projective readout of a qubit’s state in a single experimental repetition is a prerequisite for various quantum protocols of sensing and computing. The scheme is based on spin-dependent resonant excitation at cryogenic temperature combined with spin-to-charge conversion, mapping the fragile electron spin states to the stable charge states We prove this technique to work on shallow implanted NV centers, as they are required for sensing and scalable NV-based quantum registers. One option to increase the single-shot SNR is spin-to-charge conversion (SCC)[3,4] This readout approach maps the fragile spin state to the more robust charge state of the NV center, which can be read out optically with close to 100% fidelity even at room temperature[5]. A second scheme consists in tuning a narrow-linewidth laser in resonance to a cycling transition in the low-temperature excitation spectrum of the NV− center[7] In this configuration, the NV− is spin-selectively excited and producing fluorescence only if its spin state matches the used optical transition. The technique promises to be robust against strong misaligned background magnetic fields

Methods

Results

Conclusion