Large scale integration of diamond cavity with Sn vacancy

Nanophotonic cavities are a special type of optical resonators which have dimensions in the order of tens to hundreds of nanometers. They are usually implemented with incorporating Bragg reflectors/controlled index variations in the photonic structures. Nanophotonic cavities can strongly confine light/photon, and thus, can significantly enhance photon generation and collection probability from any emitter placed inside the cavity. This unique properties can be used for enhancing the radiative decay rate of a diamond color center emitter, suppressing non-favorable transitions, improving the coherence and spectral purity, spin-photon entanglement generation efficiency, etc. All of these are critical for efficient qubit readout, remote entanglement and large scale diamond based quantum computer, network system implementation. However, fabricating such nanophotonic cavities accurately in diamond and coupling the color center emitters spatially and spectrally with such cavities are highly challenging. Furthermore, a large scale fabrication and high-yield emitter-cavity coupling process has to be developed in order to realize a scalable, on-chip quantum system, where thousands of qubits can be interconnected and entangled efficiently for useful quantum computing.

Tin-vacancy (SnV) centers in diamond is particularly promising for large scale integration of quantum systems because of their charge noise insensitivity due to inversion symmetry, narrow-linewidth and larger ZPL emission (DW factor ~ 0.57), good compatibility of coupling with nanophotonic structures, long spin coherence times at temperatures above 1 K etc.

Hence, developing an integration process for large scale SnV center-cavity coupled system will be a critical step towards the realization of a useful quantum computer and network. In this project, we plan to research and develop efficient, large scale fabrication & coupling techniques for SnV center-cavity systems, which will open the route to scalable, on-chip integration of thousands of qubits in a quantum node/module. Devising a cavity design tolerant to fabrication imperfections and non-optimal emitter positioning can improve the coupling efficiency with simpler fabrication processes. The proposed fabrication processes will allow spatial tuning (placing emitter at field maxima and dipole aligning) of the cavity-emitter system through deterministic cavity fabrication and ion implantation.

[1]. Alison E. Rugar, and et al., Quantum Photonic Interface for Tin-Vacancy Centers in Diamond, Physical Review X, 11, 031021 (2021)
[2]. Maximilian Ruf, and et al., Quantum networks based on color centers in diamond, Journal of Applied Physics 130, 070901 (2021)
[3]. Noel H. Wan*, Tsung-Ju Lu and et al., Large-scale integration of artificial atoms in hybrid photonic circuits, Nature 583, 226–23 (2020).
[4]. Andreas Reiserer, Colloquium : Cavity-enhanced quantum network nodes, Rev. Mod. Phys. 94 041003 (2022)
[5]. Johannes Görlitz, and et al., Spectroscopic investigations of negatively charged tin-vacancy centres in diamond, New J. Phys. 22, 013048 (2020).
[6]. Takayuki Iwasaki, and et al., Tin-Vacancy Quantum Emitters in Diamond, Phys. Rev. Lett. 119, 253601 (2017)