[PAST EVENT] Mi Zhang: Physics Dissertation Defense
Abstract: Squeezed states of light, with field fluctuations smaller than the coherent state fluctuations (or shot noise), are used for improving accuracy of quantum-noise limited measurements, like the detection of gravitational waves. They are also essential resources for quantum information transfer protocols. We studied a squeezed vacuum field generated in hot Rb vapor via the polarization self-rotation effect. We studied the mode structure of the squeezed field by spatially-masking the laser beam after its interaction with the Rb atomic vapor. From analysis of the data we developed a multi-mode theory to simulate the mode composition of the squeezed vacuum field. Our experiments showed that the amount of observed squeezing may be limited by the complex mode structure due to the excitement of higher order spatial modes during the nonlinear atom-light interaction. We demonstrated that optimization of the spatial profile of the beam led to higher detected squeezing. Our studies are useful for enhancing precision metrology and quantum memory applications.
Bio: Mi Zhang was born in Shangqiu, a small city in the middle of China, in the year of 1990. She developed an interest in natural science as a teenager and decided to focus on physics in high school. She gained bachelor's degree of in 2011 when graduated from physics department of Fudan University, Shanghai. In the autumn of 2011, she arrived in the US and began her study for a Ph.D's degree at William & Mary. She joined Dr. Mikhailov's group in the summer of 2012 and has been working on the squeezed vacuum project since then. In the meantime, she also joined the LIGO scientific collaboration and is part of the gravitational wave detection crew. After graduation, she will work as an optical engineer back in Shanghai.