Characterization of optical and spin properties of single tin-vacancy centers in diamond nanopillars

Color centers in diamond have attracted much interest as candidates for optically active, solid-state quantum bits. Of particular interest are inversion-symmetric color centers based on group-IV impurities in diamond because they emit strongly into their zero-phonon lines and are insensitive to electric field noise to first order. Early studies of the negatively charged tin-vacancy (SnV^-) center in diamond have found the SnV^- to be a promising candidate: it has high quantum efficiency, emits strongly into its zero-phonon lines, and is expected to have a long T₂ spin coherence time at 4 K. To develop the SnV^- into a spin qubit requires further characterization, especially of the spin and optical properties of individual SnV^- in nanofabricated structures. In this work, we isolate single SnV^- centers in diamond nanopillars and characterize their emission properties and their spin response to a magnetic field. We observe narrow emission linewidths $<250$ MHz, as well as a strong polarization dependence of each transition. We also find the Zeeman splitting under a magnetic field to be in good agreement with theoretical prediction. Our results pave the way toward future employment of single SnV^- centers as optically accessible quantum memories.