Highly Coherent Nitrogen‐Vacancy Centers in Diamond via Rational High‐Pressure and High‐Temperature Synthesis and Treatment

• Published in: Advanced functional materials 2023-12, Vol.33 (52), p.n/a
• Main Authors: Zhang, Xiaoran, Liu, Kang‐Yuan, Li, Fengjiao, Liu, Xiaobing, Duan, Shuai, Wang, Jia‐Ning, Liu, Gang‐Qin, Pan, Xin‐Yu, Chen, Xin, Zhang, Ping, Ma, Yanming, Chen, Changfeng
• Format: Article
• Language: English
• Subjects: Chemical vapor deposition; Coherence; Defect annealing; diamond single crystal; Diamonds; high‐pressure and high‐temperature methods; Materials science; Nitrogen; nitrogen‐vacancy centers; quantum information science; Quantum phenomena; Substrates; Synthesis
• ISSN: 1616-301X; 1616-3028
• DOI: 10.1002/adfm.202309586

The high‐pressure and high‐temperature (HPHT) diamonds with well‐controlled defects and low stress offer an ideal host substrate for the fields of quantum information science; however, fabrication of quantum‐grade HPHT diamonds remains a pressing challenge. Here, a major advance in generating highly coherent nitrogen‐vacancy (NV) centers, a promising spin defect in diamonds, via tailored HPHT synthesis and postgrown annealing treatment is reported. The resulting well‐dispersed single NV− centers in type‐IIa diamonds exhibit long spin coherence times comparable to that of the reported chemical vapor deposition diamonds. Moreover, high‐density NV− ensembles in 〈100〉‐grown type‐Ib diamonds with superb zero‐phonon lines considerably sharper than those of native NV− centers in as‐grown diamonds, together with low splitting of resonances are produced. These findings demonstrate a superior synthesis and optimization protocol for creating high‐quality NV− centers avoiding lattice damage in diamond to meet the stringent requirements for a wide range of emerging quantum technologies. This study reports an efficient way to fabricate high‐quality NV‐ centers by controlling nitrogen content, growth orientation, and high‐pressure and high‐temperature (HPHT) annealing conditions. The HPHT synthesized and postgrowth annealed diamonds contain highly coherent single and ensemble NV− centers, showcasing outstanding performance benchmarks that are comparable to those reported for quantum‐grade chemical vapor deposition diamonds. Thus, the HPHT diamond is successfully developed into quantum‐grade.