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ESE Ph.D. Thesis Defense: “Optical and Spin Dynamics of Quantum Emitters in Hexagonal Boron Nitride at Room Temperature”

July 13 at 10:00 AM - 11:00 AM

Hexagonal boron nitride (h-BN) is a van der Waals material that hosts defect-based quantum emitters (QEs) at room temperature, providing an unparalleled platform for realizing devices for quantum technologies and studying light-matter interactions. Recent observations suggest the existence of multiple distinct defect structures responsible for QEs. Theoretical proposals suggest vacancies, substitutional atoms, and their complexes as likely defect candidates. However, experimental identification of the QEs’ electronic structure is lacking, and key details of the QEs’ charge and spin properties remain unknown. This thesis focuses on understanding the optical and spin dynamics of QEs in h-BN at room temperature. Starting with the motivation for studying quantum systems and QEs, this thesis introduces QEs in h-BN and discusses its current understanding. Next, it discusses the materials and methods developed and utilized during the course of this thesis. Next, it discusses the optical dynamics acquired using photoluminescence spectroscopy and photon emission correlation spectroscopy (PECS) and shows several QEs exhibit pure single-photon emission. It discusses the complex optical dynamics associated with excitation and relaxation through multiple electronic excited states – revealed by PECS and polarization-resolved excitation and emission. Following, it presents the optical dynamics simulations of electronic structure models that are consistent with the observations, and discusses the results in the context of ab initio theoretical calculations. Next, it discusses magnetic-field-dependent PECS that can be used as a framework to probe the presence of single spins that are otherwise elusive. Following, it presents detection and confirmation of single-spin using optically detected magnetic resonance. Finally, it discusses the spin dynamics and time-domain measurements acquired using optical and microwave pulse protocols crucial to developing methods to coherently control the QE’s spin. To conclude, it discusses the future directions that can help identify the chemical nature of QEs in h-BN and establish it as a scalable material platform for quantum technologies.

Raj Patel

ESE Ph.D. Candidate

Raj received his M.Sc. in Physics and B.E. in Mechanical Engineering from BITS Pilani – Goa, India in 2015.  His undergraduate thesis at Tata Institute of Fundamental Research, Mumbai focused on strong coupling and parametric amplification of mechanical modes of graphene resonators. He received an M.S.E. in Materials Science & Engineering from University of Pennsylvania in 2017. As a Graduate Student Fellow at the Singh Center for Nanotechnology, he worked on process development of thin film deposition and dry etch using design of experiments and statistical process control. He is currently a Ph.D. Candidate in Electrical & Systems Engineering, where he works in the Quantum Engineering Laboratory. His research interests are in understanding spin-based quantum emitters in two-dimensional materials and other solid-state systems for quantum sensing and computation applications. His research contributions can be found here.


July 13
10:00 AM - 11:00 AM
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Electrical and Systems Engineering
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Raisler Lounge (Room 225), Towne Building
220 South 33rd Street
Philadelphia, PA 19104 United States
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