Encapsulated NV-NPA SPE: a stable quantum light source nanodevice with dielectric engineering of PL lifetime

Quantum emitters and plasmonic nanocavities are key elements in the advancement of quantum photonics, offering unique potential for quantum information processing, communication, and computing. [1] Quantum emitters, such as atoms, ions, and quantum dots, are capable of emitting single photons, a critical resource for quantum technologies. Plasmonic nanocavities—which confine light to volumes below the diffraction limit—greatly enhance light-matter interactions and increase photon emission rates. Coupling quantum emitters with plasmonic nanocavities result in highly efficient single-photon sources, even at room temperature. However, challenges remain in optimizing photon outcoupling and achieving indistinguishable single-photon emission. Hybrid plasmonic structures, like the nano-patch antenna (NPA) coupled to nitrogen-vacancy (NV) centers, have been developed to enhance photon emission. [2–4] However, issues such as material degradation and the need for dielectric encapsulation persist. In this work, we demonstrate that atomic layer deposition (ALD) of Al₂O₃ encapsulation on an NV-NPA system extends the active lifetime of the single-photon emitter to over three months. Engineering of such a thin-film dielectric encapsulation optimizes the Purcell factor, fine-tunes the mode volume of the antenna and cavity modes, and provides additional degrees of control. We explore the mechanisms behind this enhancement, highlighting the importance of dielectric environment optimization for plasmonic nanocavities in future quantum photonic applications.



[1] S. I. Bogdanov, A. Boltasseva, and V. M. Shalaev, Overcoming Quantum Decoherence with Plasmonics, Science. 364, 532 (2019).

[2] S. I. Bogdanov et al., Ultrafast Quantum Photonics Enabled by Coupling Plasmonic Nanocavities to Strongly Radiative Antennas, Optica 7, 463 (2020).

[3] S. I. Bogdanov et al., Ultrabright Room-Temperature Sub-Nanosecond Emission from Single Nitrogen-Vacancy Centers Coupled to Nanopatch Antennas, Nano Lett. 18, 4837 (2018).

[4] C. C. Chiang et al., Chip-Compatible Quantum Plasmonic Launcher, Adv. Opt. Mater. 8, 1 (2020).