Optical Control of Color Centers in Nanoscale Diamond

Abstract

Emerging technologies such as quantum key distribution, quantum internet, and optical quantum computing rely fundamentally on scalable, high-performance single-photon sources (SPS). Silicon-vacancy (SiV) centers in diamonds are compelling candidates for their narrow-linewidth optical transitions and spin-photon interfaces. However, achieving indistinguishable photons at practical temperatures remains a major challenge due to rapid phonon-induced dephasing, and requires >103 Purcell factors for >77K. Moreover, issues such as scalability, modest brightness, poor light extraction, and low quantum efficiency continue to impede progress toward practical quantum photonic platforms. Here, this dissertation presents a potential viable platform using plasmonic nanogap cavities coupled to 10 nm diamond membranes. The extreme subwavelength cavity mode volume yielded an ultrafast 5.5 ps single photon lifetime, or a 210-fold Purcell enhancement – less than one order of magnitude from liquid nitrogen operation regime. Detailed mechanistic analysis reveals contributions from enhanced radiative rate, collection efficiency, and quantum efficiency as high as 0.6 synergistically enhanced the brightness up to 4800-fold. Complementing this, thin-film interference effects in diamond membranes are exploited to modulate the excitation and emission of SiV centers. Tailoring membrane thickness enables selective photoluminescence enhancement by up to 36-fold or emission suppression. This platform offers a simple, hybrid functionality, combining passive photonic filtering and emission control that could open new avenues for both classical and quantum optical integration. Finally, we explore the deterministic integration of nanodiamonds containing nitrogen vacancy centers into lithographically defined plasmonic cavities. Initial demonstrations confirm precise spatial placement and structural coupling, offering a promising pathway towards scalability. Together, these results advance the frontier toward practical, room-temperature-compatible single-photon sources with the potential for indistinguishable emissions. As research continues to advance, scalable indistinguishable photons at room temperature could be well within reach in the near future.