Multiple Tin-Vacancy Centers in Diamond with Nearly Identical Photon Frequency and Linewidth

Tin-vacancy (Sn-$V$) centers in diamond, which possess good optical and spin properties, are a promising system for constructing quantum network nodes. Tin atoms are heavy, though, and generating photons with identical wavelength and linewidth from multiple Sn-$V$ emitters is challenging, due to the strain in the diamond host material. This study shows that multiple Sn-$V$ centers, formed deep within bulk diamond by ion implantation and high-temperature annealing, emit nearly identical photons. This leads to two-photon interference from distant centers, an important step toward building quantum network nodes.