Investigation of the silicon vacancy color center for quantum key distribution.

Yan Liu,E Wu,Fedor Jelezko,Takahiro Shinada,Shinobu Onoda,Takeshi Ohshima,Youying Rong,Petr Siyushev,Heping Zeng,Tokuyuki Teraji,Liam Paul Mcguinness,Junichi Isoya,Syuto Tamura,Botao Wu,Takashi Tanii

doi:10.1364/oe.23.032961

Abstract

Single photon sources (SPS) are crucial for quantum key distribution. Here we demonstrate a stable triggered SPS at 738 nm with linewidth less than 5 nm at room temperature based on a negatively charged single silicon vacancy color center. Thanks to the short photon duration of about 1.3-1.7 ns, by using high repetition pulsed excitation at 30 MHz, the triggered single photon source generates 16.6 kcounts/s. And we discuss the feasibility of this triggered SPS in the application of quantum key distribution.

Highlights

Demonstrations of quantum key distribution (QKD) have been achieved with a variety of photon sources, such as attenuated laser pulses, photon pairs from parametric down conversion, and single photons from quantum dots or individual color centers in diamond [1,2,3,4,5,6,7]
Nitrogen vacancy color centers (NV), silicon vacancy color centers (SiV), nickel-related color centers, and chromium-related color centers have been considered as candidate Single photon sources (SPS) [8,9,10,11,12,13,14]
Under pulsed excitation with our scanning confocal microscope setup, we observe SiV- centers exhibiting a zero phonon line (ZPL) at 738 nm with narrow linewidth of 5 nm full-width at half-maximum (FWHM), short photon duration of about 1.3-1.7 ns, as well as 50% linear polarization contrast at room temperature

Summary

Introduction

Demonstrations of quantum key distribution (QKD) have been achieved with a variety of photon sources, such as attenuated laser pulses, photon pairs from parametric down conversion, and single photons from quantum dots or individual color centers in diamond [1,2,3,4,5,6,7]. As the NV emission is reported to occur via two orthogonal dipoles, the polarization contrast of a single NV center is usually sub-unity [18] These properties limit the application of NV centers to QKD. It was reported recently that the negatively charged silicon vacancy color center (SiV-) has narrow emission around a zero phonon line (ZPL) of 738 nm with a short excited state lifetime, usually about 1 ns [19,20,21,22,23,24,25,26]. Under pulsed excitation with our scanning confocal microscope setup, we observe SiV- centers exhibiting a ZPL at 738 nm with narrow linewidth of 5 nm full-width at half-maximum (FWHM), short photon duration of about 1.3-1.7 ns, as well as 50% linear polarization contrast at room temperature. Our experimental results indicate that pulsed laser excitation of SiV- has great potential as a stable triggered SPS with applications in higher key rate and improved safety-level quantum key distribution

Sample preparation and experimental setup

Experimental result

Discussion

Conclusion