PhD Thesis Defense - Anil Bilgin

Engineering dipolar interactions in wide bandgap semiconductors using donor-acceptor pairs

Harnessing the optical and electronic properties of point defects in wide bandgap semiconductors offers a pathway to scalable quantum systems, enabling coherent control and long-range coupling between qubits embedded in solid-state environments. In this talk, I will present two complementary studies that explore how donor-acceptor pairs (DAPs) can be used to realize such functionalities in diamond and silicon carbide (SiC). First, I will describe how we used density functional theory to systematically characterize the electronic structure and photophysics of a broad set of substitutional defects in bulk diamond and SiC. These calculations revealed that DAPs possess unusually large electric dipole moments, which serve as the building blocks for engineered long-range interactions via optical switching. We demonstrated that certain DAP combinations exhibit highly desirable optical signatures, such as high Debye-Waller factors, while also enabling long-range dipolar coupling strengths suitable for conditional logic operations. Building on this insight, we then extended this work to examine DAPs and surface-defect pair (SDP) configurations near various SiC surfaces. Here, I will show how the surface can act as a stabilizing agent that aligns the resulting dipole moments. This alignment - absent in bulk ensembles - is critical for optical addressability, polarization selective coupling, and the realization of two-dimensional quantum sensor and emitter arrays. Finally, we show the photoionization and stimulated emission cross sections for these near-surface systems reveal significant polarization-dependent modulation that can be leveraged for device integration. Together, these studies outline a roadmap for engineering dipolar interactions in semiconductors and suggest new directions for integrating them into scalable quantum architectures.

 

Zoom link: https://uchicago.zoom.us/j/99061286440?pwd=YtyajncG2V2YJyw0awwADuinihQ8aF.1