Spin-Phonon Coupling in Nanodevices

Abstract

Many physical implementations of quantum bits interact to varying degrees with mechanical vibrations. The ability to nanostructure a qubit’s local environment presents new opportunities to utilize mechanical modes in a coherent spin-phonon interface, and to connect different types of quantum systems. Some solid-state spin qubits like the silicon vacancy center (SiV) in diamond have notably large strain susceptibilities. Integrating SiV centers with engineered wavelength scale nanomechanical resonators can provide the high quality factors and small mode volumes required to enhance the strength of spin-phonon interactions towards the quantum coherent regime. This thesis details the characterization of high Q factor optomechanical crystal (OMC) resonators in diamond with coupled intracavity SiV centers. We make use of the resonant SiV-optical cavity spin-photon interface to probe the spin’s coherence properties and to observe spectroscopic signatures of spin-phonon coupling when the mechanical modes of the structure are near their motional ground state. We independently probe the frequency and intrinsic linewidth of the mechanical swelling mode of the OMC via the optomechanical interaction. We observe that mechanical dissipation currently limits the cooperativity of the spin-phonon interface. We discuss how future devices could eventually reach the quantum coherent coupling regime.