Scalable Focused Ion Beam Creation of Nearly Lifetime-Limited Single Quantum Emitters in Diamond Nanostructures (1610.09492v1)

Abstract: The controlled creation of defect center---nanocavity systems is one of the outstanding challenges for efficiently interfacing spin quantum memories with photons for photon-based entanglement operations in a quantum network. Here, we demonstrate direct, maskless creation of atom-like single silicon-vacancy (SiV) centers in diamond nanostructures via focused ion beam implantation with $\sim 32$ nm lateral precision and $< 50$ nm positioning accuracy relative to a nanocavity. Moreover, we determine the Si+ ion to SiV center conversion yield to $\sim 2.5\%$ and observe a 10-fold conversion yield increase by additional electron irradiation. We extract inhomogeneously broadened ensemble emission linewidths of $\sim 51$ GHz, and close to lifetime-limited single-emitter transition linewidths down to $126 \pm13$ MHz corresponding to $\sim 1.4$-times the natural linewidth. This demonstration of deterministic creation of optically coherent solid-state single quantum systems is an important step towards development of scalable quantum optical devices.

Scalable Creation of Nearly Lifetime-Limited Single Quantum Emitters in Diamond Nanostructures

This paper explores a deterministic and scalable approach to creating nearly lifetime-limited silicon-vacancy (SiV) centers in diamond nanostructures, promising significant advancements in quantum optics and quantum communication. The researchers employ focused ion beam (FIB) implantation for precision placement of SiV centers relative to photonic devices such as nanocavities, demonstrating a post-fabrication implantation method that enables integration with pre-evaluated nanophotonic structures.

Key Findings

• Precision and Yield: The paper outlines the experimental setup and results showing FIB's capability to position Si ions with an impressive lateral precision of approximately 32 nm and a positioning accuracy of less than 50 nm relative to a nanocavity's mode maximum. The researchers achieve a Si+ ion to SiV conversion yield of about 2.5%, which could be enhanced tenfold via electron irradiation.
• Optical Properties: At cryogenic temperatures, SiV centers exhibit single-emitter transition linewidths down to 126 ± 13 MHz, corresponding to 1.4 times the natural linewidth, suggesting excellent optical coherence for potential applications in quantum networks.
• Implications for Quantum Devices: The successful implantation of SiV centers in diamond photonic structures, such as L3 cavities, highlights the practicality of this method for fabricating efficient light-matter interfaces. This opens avenues for reliable integration of quantum defects into scalable photonic devices.

Proposed Mechanisms and Enhancements

The paper discusses several parameters influencing the Si to SiV conversion yield, including implantation dose and ion energy. An increase in vacancy density through electron irradiation facilitates a more efficient conversion. These results indicate potential optimizations for enhancing yield further, like repeated implantation cycles and co-implantation strategies.

Technical Contributions and Future Directions

The method proposed in this paper achieves spatial positioning accuracy and optical coherence comparable to naturally occurring SiV centers, presenting a scalable approach to creating large arrays of indistinguishable single-photon sources. This advancement is expected to disruptively contribute to modular quantum computing, all-photonic quantum repeaters, and linear optics quantum computing.

Further research could explore improvements in implantation yield and transitions to deterministic single-emitter production. The integration of SiV centers in diverse host materials such as silicon carbide or molybdenum disulfide could provide broader applications in quantum technologies. Overall, the techniques presented in this paper offer critical advancements toward the mass production of quantum optical devices and the implementation of robust quantum networks.