Quantum control of optically active defects in the solid state

A common thread in the realization of quantum computers, quantum networks, and quantum sensors is the search for promising physical platforms. The dislocations of atoms in the solid state, referred to as defects, have historically been deemed undesirable as they can be deleterious to the operation of electronic and optoelectronic devices. In 1997, it was demonstrated that a single nitrogen-vacancy (NV) center defect in diamond could act as a stable single photon source [1]. In the same study, the electronic spin of the same defect was optically initialized and read out. Remarkably, both of these achievements occurred under ambient conditions. In the decades that have followed, the study of optically active defects in the solid state have garnered significant interest for quantum applications. Motivated by this, in this thesis we demonstrate experimental progress in defects in three materials: silicon carbide, diamond, and sapphire. Silicon carbide is a wide band-gap semiconductor with a mature manufacturing industry. In this material, we show the integration of surface defects (formed at the SiC/SiO2 interface) into microdisk resonators, showing an enhancement in single photon emission. Additionally, we construct a confocal microscopy apparatus and demonstrate room-temperature optically-detected magnetic resonance of silicon-vacancy defects in ~50 nm diameter SiC nanoparticles, further motivating their application for quantum sensing and nanophotonics. While NV-centers have been widely studied, we demonstrate coherent control of the electronic spin states, and coupling to their neighboring nuclear spins, using an apparatus that operates in ambient conditions, outside an otherwise carefully controlled environment of a research laboratory, and which can be constructed for ~USD 20k. This has enabled the development of a teaching lab that has been incorporated into a quantum engineering course for three consecutive years. Lastly, we upgrade a dilution refrigerator for optical access, and using the spin properties of Cr3+ defects in sapphire (ruby), conduct all-optical thermometry, reaching lattice temperatures as low as 143 mK under continuous laser excitation. We measure the spin relaxation time down to these unprecedented temperatures, and demonstrate optically detected magnetic resonance within the rich spin structure of the Cr3+ ions. The sum contribution of these results is the development of the experimental apparatus and techniques in probing the optical and spin characteristics of novel optically active defects, both at room temperature and cryogenic temperatures, which paves the way for the development of advanced spin-photon interfaces. [1] A. Gruber et al. “Scanning Confocal Optical Microscopy and Magnetic Resonance on Single Defect Centers”. In: Science 276.5321 (1997), pp. 2012–2014.

Grantor dc:publisher

UNSW, Sydney

Year dc:date

2021

Author dc:creator

• Sewani, Vikas Kanayalal

• Nitrogen-vacancy center
• Quantum computing
• Solid state
• Diamond
• Electron spins
• Hamiltonian
• Coherent control
• Quantum engineering
• Teaching lab
• Ruby
• Spin thermometry
• Spin relaxation
• Chromium
• Sapphire
• Crystal defects
• Optical spectroscopy
• Microdisk resonators
• Silicon-vacancy
• Nanoparticles
• Nanophotonics
• Point defects
• Silicon carbide
• Magnetic resonance
• Spin control
• Confocal microscopy
• Optically-detected magnetic resonance
• Quantum sensing

Statement dc:rights

• open access
• CC BY-NC-ND 3.0
• free_to_read

Licence

• https://purl.org/coar/access_right/c_abf2
• https://creativecommons.org/licenses/by-nc-nd/3.0/au/

Language dc:language

EN

Identifier

https://doi.org/10.26190/unsworks/22568

OAI identifier oai:identifier

oai:unsworks.library.unsw.edu.au:1959.4/70911