Lattice Atom Interferometry in an Optical Cavity

Abstract

Atom interferometers are powerful tools for both measurements in fundamental physics and inertial sensing applications. Their performance, however, has been limited by the available interrogation time of freely falling atoms in a gravitational field. In this thesis, we realize an unprecedented interrogation time of 20 seconds by suspending the spatially separated atomic wavepackets in the resonant lattice of an optical cavity. Unlike traditional atom interferometers, our approach allows gravitational potentials to be measured by holding, rather than dropping, atoms. After seconds of hold time, gravitational potential energy differences from as little as microns of vertical separation generate megaradians of interferometer phase. This trapped geometry suppresses the phase variance due to vibrations by three to four orders of magnitude, overcoming the dominant noise source in atom-interferometric gravimeters. i To Mommy, Daddy, Xiaodude, and Andrew For the life you have built for me, for your light that shines warmly on me, and for your love that knows me.ii ContentsContents ii List of Figures v List of Tables viiWhen I joined the experiment in Spring 2016, I joined an amazing team consisting of a senior graduate student Matt Jaffe, and a postdoc Philipp Haslinger. My first day, Holger, Matt, Philipp and I went to Coffee Lab to grab coffee and talk, and I was immediately hooked on the experiment. We went to lab, and Matt walked me through turning on the experiment -a thing I've done maybe a couple hundred times in the 4 years since. In this time, I have been lucky to gain new teammates on the cavity, including a visiting master's student, Sofus Kristensen, and a visiting postdoc, Logan Clark. Going forwards, I have watched an incredible team in our postdoc Cristian Panda, and graduate student James Egelhoff, steadily do the "essential work" of transforming our experiment into a better version of itself while the world was in quarantine.With the cavity experiment, I have been lucky to experience how exciting science can be in the best of times. I remember the first signs that the blackbody force was attractive. I remember taking data for the juggling interferometer, and turning up the loop number to 50 and incredulously seeing interference still. With the lattice interferometer, I had a lot of these moments. I remember the first time we saw a 10 second lattice interferometer. It was night. I was in lab having just turned the hold time up to 10 seconds, and Matt TeamViewer-ed into our lower experiment computer. We opened up a notepad text file; he asked if we were going for 10 seconds; we went for it; and we saw fringes begin to show up after a couple minutes. I was super excited. After that, it was turning up the hold time to 15 seconds and letting it run over lunch, while we went to House of Curries and ate our Indian food in suspense and texting Holger. After that, running long interferometer hold times became like a very suspenseful but much too slow movie, and we lost our sparkle for long holds. And exactly then...