Tin-Vacancy Quantum Emitters in Diamond (1708.03576v1)

Abstract: Tin-vacancy (SnV) color centers were created in diamond by ion implantation and subsequent high temperature annealing up to 2100 {\deg}C at 7.7 GPa. The first-principles calculation suggests that the large atom of tin can be incorporated into the diamond lattice with a split-vacancy configuration, in which a tin atom sits on an interstitial site with two neighboring vacancies. The SnV center shows a sharp zero phonon line at 619 nm at room temperature. This line splits into four peaks at cryogenic temperatures with a larger ground state splitting of ~850 GHz than those of color centers based on other IV group elements, silicon-vacancy (SiV) and germanium vacancy (GeV) centers. The excited state lifetime was estimated to be ~5 ns by Hanbury Brown-Twiss interferometry measurements on single SnV quantum emitters. The order of the experimentally obtained optical transition energies comparing with the SiV and GeV centers is good agreement with the theoretical calculations.

Overview and Analysis of Tin-Vacancy Quantum Emitters in Diamond

The paper "Tin-Vacancy Quantum Emitters in Diamond" by Iwasaki et al. provides a meticulous exploration into the creation and properties of tin-vacancy (SnV) color centers in diamond. Constructed through ion implantation and subsequent high temperature annealing, SnV centers emerge as promising contenders for quantum information processing, a field mainly dominated by nitrogen-vacancy (NV) and silicon-vacancy (SiV) centers previously. This paper distinguishes itself by leveraging the unique properties of tin, a Group IV element, to achieve substantial advancements in quantum emitter technology.

The research primarily focuses on the optical characteristics of SnV centers. A key finding is the sharp zero phonon line (ZPL) observed at 619 nm, exhibiting a full width half maximum (FWHM) significantly reduced to ~6.2 nm under optimal annealing conditions. Notably, the ground state splitting is about 850 GHz, a substantial improvement over SiV (~50 GHz) and GeV (~170 GHz) centers. This noteworthy enhancement is attributed to the introduction of heavier tin atoms, which confer stronger spin-orbit coupling, thus increasing energy level splitting.

The team utilized IIa-type single-crystal diamond substrates with minimal nitrogen impurities and executed ion implantation with energies ranging from 130-150 keV and post-annealing temperatures up to 2100 °C under high pressures of 7.7 GPa. These parameters were essential to avoid graphitization and enhance the structural integrity of the diamond.

In terms of practical implications, SnV centers demonstrate improved quantum coherence. The excited state lifetime of the SnV center is approximately 5 ns, an aspect determined via Hanbury Brown-Twiss (HBT) interferometry. Moreover, the linewidth reduction and suppression of unintentional fluorescence were achieved by annealing, indicative of the controlled creation of quality emitters.

From a theoretical perspective, the paper features first-principle calculations elucidating the atomic structure and energy level configurations of SnV centers. The tin atom adopts a split-vacancy configuration akin to SiV and GeV centers but with increased atomic interactions. Such structural insights deepen the understanding of vacancy-centers' optical behavior in diamond, providing a framework that could guide future exploration in the quantum optics domain.

The implications of this research are manifold. Firstly, the larger ground state energy splitting could ameliorate phonon-mediated decoherence, a significant barrier in quantum computing and spintronic applications. Secondly, the correlation between atomic size and energy splitting introduced by heavier elements like tin presents potential pathways for optimizing other Group IV vacancy centers.

Summarily, this research underscores the advantage of incorporating larger atomic species into diamond lattices, extending the applicability and efficacy of quantum emitters. Future explorations could explore other heavy atom integrations, further refining the balance between quantum efficiencies and material characteristics. As efforts continue to enhance spin coherence times, this paper lays a crucial foundation for advancing quantum emission technologies.