Princeton University

School of Engineering & Applied Science

Spin and Optical Characterization of Defects in Group IV Semiconductors for Quantum Memory Applications

Brendon Rose
Engineering Quadrangle J401
Friday, November 3, 2017 - 10:00am to 11:30am

Quantum technologies promise to provide advantages to their classical counterparts by leveraging the principles of quantum mechanics. These principles are best utilized when the quantum state is pure, but interactions with the environment easily ruin the purity. This gives rise to the need for a specialized system that preserves the state in a long-lived quantum memory, immune to environmental noise. Defect spins in semiconductors are attractive candidates for implementing such a quantum memory because several systems have been identified with the ability to store quantum information over a long period of time.
This thesis is focused on the characterization of the spin and optical degrees of freedom of highly coherent solid-state defect spins in both silicon and diamond in the context of quantum memory applications. Both materials are promising hosts for highly coherent defect states. Their mature material technologies allow for the availability of highly pure and highly isotopically enriched single-crystals which greatly reduces the magnetic and electric field noise present in host lattice.
The first part on phosphorus donor electron spins presents the first realization of strong coupling with spins in silicon, allowing for quantum information encoded in microwave photons to be transferred to the phosphorus donor spin ensemble before it is lost. In the second part, we characterize the spin properties of the nitrogen vacancy center in diamond (NV-) in the presence of a large magnetic field, which provides insight into utilizing NV- as a nanoscale sensor. Lastly, we perform characterization of a new color center in diamond, the neutrally charged silicon-vacancy center, and find that it has attractive, highly sought-after properties for use as a quantum memory in a quantum repeater scheme. We find that it has both highly coherent optical and spin degrees of freedom, the combination of which has eluded all previous solid state defects.