Place: Engineering 3609 and virtual-https://uwmadison.zoom.us/j/94242686133?pwd=MjhURDFhVFJjYU1VY25Vcit5dElZZz09
Speaker: Zhaoning April Yu , Physics PhD Graduate Student
Abstract: The booming of quantum technologies offers exciting opportunities in the field of optics. This thesis includes our effort to address three optical challenges when building a quantum repeater or a quantum chemical sensor, they are: (1) how to engineer diffraction gratings for trapping cold atom clusters; (2) how to efficiently generate optical bottle beams using a single surface-patterned chip; and (3) how to extract fluorescence from color centers in diamond without damaging the diamond surface. To interact with a small (atom-scale) quantum system, miniaturized optical components are often needed with micro- or nanometer structuring. Such compact structuring poses requirements in both simulation and fabrication methods. On the one hand, when designing and evaluating a micro- or nano optical component, unlike conventional bulky optics where light can be approximated as rays, the electromagnetic field must be calculated with nm-scale spatial resolution. On the other hand, when making a micro- or nano optical component, conventional mechanical polishing can not provide sufficient accuracy, thus researchers resort to advanced lithography techniques (such as electron-beam lithography, laser lithography) which has already been used in the semiconductor industry. The methods are introduced and discussed in details for each application scenario. By using finite-difference time-domain (FDTD) simulation method and electron-beam lithography fabrication method, we demonstrate: (1) a grating chip for trapping dual atomic species; (2) an optical metasurface for generating a bottle beam array with a single Gaussian beam luminance; and (3) a silicon light extractor for enhancing the fluorescence collection from nitrogen-vacancy (NV) defects in diamond.