Developing a Platform for cQED Studies of Silicon Vacancy Centers in Diamond within the Good-Cavity Limit
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Date
2023-03-24
Authors
Pauls, Abigail
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Publisher
University of Oregon
Abstract
Silicon vacancy centers (SiVs) in diamond are local defects in the diamond lattice that behave as atomic-like systems with electronic energy levels and optical transitions. The SiV's optical properties and long spin decoherence times ($> \! 10$ ms @ 100 mK), along with its ability to be integrated into nano-engineered devices while maintaining its optical coherence, make it an attractive option as a solid state spin qubit for applications in quantum information.\cite{ref23,ref24,ref25} Here I present my work to develop a composite platform for cavity quantum electrodynamics (cQED) studies of SiVs in diamond in the good-cavity limit, $\kappa<g<\gamma$, where $\kappa,\:g,$ and $\gamma$ are the cavity decay rate, single-photon coupling rate, and excited state decay respectively. The system utilizes a strain-tunable silica microsphere optical resonator in contact with a 100 nm thin SiV diamond membrane which couples to the cavity modes via the external evanescent field. This system takes advantage of the exceptionally narrow cavity linewidths ($<$50 MHz) of microspheres to enable cQED studies in the good cavity limit and eventually allow cavity mediated control of the SiV spin state through the use of three-level $\Lambda$ systems. Cavity transmission measurements confirm that cavity mode broadening can be as small as 3 MHz when the membrane is in contact with the sphere. Photoluminescence (PL) and Photoluminescence Excitation (PLE) spectroscopy of the composite system show efficient coupling of SiV fluorescence into the cavity modes with single SiV optical transitions that are spectrally resolvable ($\gamma/2\pi \approx$ 200-400 MHz.) Strain tuning of the cavity has been demonstrated over a range of 500 GHz, and the system has been made robust to the vibration and acoustic noise created by the operation of the cryostat that keeps the system at 4 K. A theoretical estimate of the single photon coupling rate ($g/2\pi=150$ MHz) suggests this system can reach cooperativities of $C\approx 10$, which should be sufficient to observe cQED coupling effects in the SiV-cavity system.
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Keywords
cQED, Optical Cavity, Quantum Optics, Silicon Vacancy