University of New Mexico UNM Digital Repository Physics & Astronomy ETDs Electronic Theses and Dissertations 1-28-2015 Rydberg Excitation of Single Atoms for Applications in Quantum Information and Metrology Aaron Hankin Follow this and additional works at: https://digitalrepository.unm.edu/phyc_etds Recommended Citation Hankin, Aaron. "Rydberg Excitation of Single Atoms for Applications in Quantum Information and Metrology." (2015). https://digitalrepository.unm.edu/phyc_etds/23 This Dissertation is brought to you for free and open access by the Electronic Theses and Dissertations at UNM Digital Repository. It has been accepted for inclusion in Physics & Astronomy ETDs by an authorized administrator of UNM Digital Repository. For more information, please contact [email protected]. Aaron Hankin Candidate Physics and Astronomy Department This dissertation is approved, and it is acceptable in quality and form for publication: Approved by the Dissertation Committee: Ivan Deutsch , Chairperson Carlton Caves Keith Lidke Grant Biedermann Rydberg Excitation of Single Atoms for Applications in Quantum Information and Metrology by Aaron Michael Hankin B.A., Physics, North Central College, 2007 M.S., Physics, Central Michigan Univeristy, 2009 DISSERATION Submitted in Partial Fulfillment of the Requirements for the Degree of Doctor of Philosophy Physics The University of New Mexico Albuquerque, New Mexico December 2014 iii c 2014, Aaron Michael Hankin iv Dedication To Maiko and our unborn daughter. \There are wonders enough out there without our inventing any." { Carl Sagan v Acknowledgments The experiment detailed in this manuscript evolved rapidly from an empty lab nearly four years ago to its current state. Needless to say, this is not something a graduate student could have accomplished so quickly by him or herself. The success of this experiment and its swift progression are largely a product of the intuition, experience, and hard of work of several staff scientists at Sandia. First and foremost, I would like to thank my advisor, Grant Biedermann, for all the guidance he gave on the experiment. His leadership and quick thinking were critical for rapidly addressing issues with the experiment as they arose, and his exceptional skills in laser cooling and workmanship with all-glass vacuum cell assemblies were critical to the successes of this project. Paul Parazzoli came onto the project as a postdoc shortly after I started at Sandia, and he drove much of the early success in the lab, including our first demonstration of single-atom trapping as well as the single-atom interferometer. I thank Paul for his contributions and invaluable advice in the lab, and for being an excellent mentor with respect to my professional career. I thank James Chou for his integral contributions to the experiment, which include the construction of the ultraviolet laser system and the development of the FPGA-computer interface for high-data rate single-atom reuse. In addition to a fresh perspective and far-reaching technical expertise, James brought with him an energy to the lab that motivated and challenged me to approach single- atom trapping with a new mindset. Yuan-Yu Jau provided a theoretical expertise in atomic physics that was a constant source of direction and essential to the success of the experiment. I thank him for these contributions and for his willingness to advise me on my own meager efforts to develop a theoretical understanding of the physics relevant to this experiment. Finally, I thank Peter Schwindt, George Burns, Amber Young, John Sterk, Cort Johnson, Anthony Colombo, Todd Barrick, Susan Clark, Hayden Mcguiness, Michael Mangan, Francisco Benito, Kevin Fortier, Peter Maunz, Darrell Armstrong, and many others for their contributions to the experiment and/or their support during my time at Sandia. The collaboration between Sandia and the CQUIC group at UNM, through Ivan Deutsch and Carl Caves, provided the opportunity for me to work on this research project. Carl aided me in getting an initial foot in the door at Sandia and took on a helpful role in ensuring that I remain on track for the completion of my dissertation. Our project at Sandia collaborated with Ivan Deutsch, my official academic advisor, on several theoretical aspects of the experiment. It was through engaging conversations with Ivan and his student, Bob Keating, and postdoc, Rob Cook, that I was able to develop a working simulation for the controlled-phase gate discussed near the end of this work. As fellow UNM graduate students working in the same lab, Akash Rakholia and Andrew Ferdinand were always available for engaging conversation regarding our vi respective experiments. Akash in particular was alwasy ready to offer his own engaging perspective on nearly any topic. Additionally, I would like to thank Shashank Pandey, Munik Shrestha, Jonas Anderson, Matthias Lang, Chris Cesare, and many other fellow UNM graduate students for great conversations, in both academic and personal contexts. Finally, I thank masters thesis advisor, Andrzej Sieradzan, for introducing me to atomic physics in a research setting and for providing me with time to tinker with cold atoms for the first time. I am forever in debt to my parents, Sue and Don, and my siblings, Sean, Shanon, and Adam, for their continuing support throughout the duration of my academic career. I would not have reached this point in my life without the sacrifices and encouragement of my family. Finally, I thank my wife, Maiko, for her limitless support and patience with me when I spent long days and late nights working on the experiment. This project was funded internally at Sandia through the Laboratory Directed Research and Development program. I thank this program for its funding, without which this work could not have happened. Sandia National Laboratories is a multi-program laboratory managed and operated by Sandia Corporation, a wholly owned subsidiary of Lockheed Martin Corporation, for the U.S. Department of Energy's National Nuclear Security Administration under contract DE-AC04-94AL85000. vii Rydberg Excitation of Single Atoms for Applications in Quantum Information and Metrology by Aaron Michael Hankin B.A., Physics, North Central College, 2007 M.S., Physics, Central Michigan Univeristy, 2009 Ph.D., Physics, University of New Mexico, 2014 Abstract With the advent of laser cooling and trapping, neutral atoms have become a founda- tional source of accuracy for applications in metrology and are showing great potential for their use as qubits in quantum information. In metrology, neutral atoms provide the most accurate references for the measurement of time and acceleration. The unsurpassed stability provided by these systems make neutral atoms an attractive avenue to explore applications in quantum information and computing. However, to fully investigate the field of quantum information, we require a method to generate entangling interactions between neutral-atom qubits. Recent progress in the use of highly-excited Rydberg states for strong dipolar interactions has shown great promise for controlled entanglement using the Rydberg blockade phenomenon. I report the use of singly-trapped 133Cs atoms as qubits for applications in metrology and quantum information. Each atom provides a physical basis for a single qubit by encoding the required information into the ground-state hyperfine viii structure of 133Cs. Through the manipulation of these qubits with microwave and optical frequency sources, we demonstrate the capacity for arbitrary single-qubit control by driving qubit rotations in three orthogonal directions on the Bloch sphere. With this control, we develop an atom interferometer that far surpasses the force sensitivity of other approaches by applying the well-established technique of light- pulsed atom-matterwave interferometry to single atoms. Following this, we focus on two-qubit interactions using highly-excited Rydberg states. Through the development of a unique single-photon approach to Rydberg excitation using an ultraviolet laser at 319 nm, we observe the Rydberg blockade interaction between atoms separated by 6.6(3) µm. Motivated by the observation of Rydberg blockade, we study the application of Rydberg-dressed states for a quantum controlled-phase gate. Using a realistic simulation of the dressed-state dynamics, we calculate a controlled-phase gate fidelity of 94% that is primarily limited by Doppler frequency shifts. Finally, we employ our single-photon excitation laser to measure the Rydberg-dressed interaction, thus demonstrating the viability of this approach. ix Contents List of Figures xiii List of Tables xvii Glossary xix 1 Introduction1 1.1 Single-atom 133Cs qubits.........................4 1.2 Overview of the experiment.......................5 1.3 Organizational overview.........................7 2 Single-Atom Control 10 2.1 Laser cooling and trapping techniques.................. 11 2.1.1 Dynamic polarizability calculation................ 13 2.1.2 Optical dipole trap........................ 16 2.1.3 Magneto-optical trap....................... 21 2.2 Loading single atoms in micron-sized dipole traps........... 25 Contents x 2.2.1 Single-atom trapping apparatus................. 28 2.2.2 Optimization of single-atom imaging.............. 30 2.2.3 Detecting atom presence and internal state........... 31 2.2.4 Arbitrary dipole trap arrays with two-dimensional holography............................ 36 2.3 Single qubit control............................ 38 2.3.1 Single-qubitσ ^x andσ ^y control.................