The proposed experiments focus on the observation and control of interactions between, and within, highly-excited Rydberg atoms. The project represents one component of a broader effort within the PI's group in which lasers and coherent fields are used to manipulate quantum dynamics in atomic and molecular systems. This general theme is shared by many in atomic, molecular and optical physics research, with potential applications to coherent control and surveillance of chemical reactions, quantum information processing, and direct simulation of model condensed matter systems. The proposed work will be performed over a 4 year period in two different laser facilities at the University of Virginia. The first is the PI's 1,600 square foot laboratory in the Physics Department, and the second is a shared 2,500 square foot multi-disciplinary laser laboratory in the Chemistry Department. The experiments will utilize laser, vacuum, atomic beam, atom trap, and detection equipment currently in the laboratories.
The research performed under this project addressed several fundamental questions relevant to how the quantum electronic behavior of electrons in atoms are modified by the presence of other electrons, either within the same atom or within neighboring atoms. Moreover, the experiments explored the extent to which that behavior can be controlled and manipulated using lasers and electric fields, or exploited to enable sensitive and fast radiation detectors. The experiments utilized combinations of brief laser and electric field pulses to influence atoms with one or more highly-excited "Rydberg" electrons. Such atoms are useful because: they are particularly sensitive to neighboring atoms and the motion of electrons within them is sufficiently slow that it can be probed with very brief laser pulses. Moreover, when the atoms are laser cooled to ultra-low temperatures, the relative positions of the atoms are roughly constant over relatively long periods of time, and can be strongly influenced by the dipole forces between atoms. In one experiment we were able to directly measure energy transfer between two highly-excited electrons on the same atom, potentially paving the way for analogous measurements in molecules which might reveal phenomena underlying numerous complex chemical processes. In another experiment, we were able to confirm that the quantum nature of two or more atoms coupled by their mutual dipole interactions persist over times that are more than a factor of 10-100x longer than previously thought. This is potentially important for implementations of quantum computing or quantum information processing using cold Rydberg atom platforms. In addition, we demonstrated a new ultrafast detector for measuring THz radiation waveforms based on the sensitivity of Rydberg atoms to external electric fields. As noted above, the results of this project may impact fundamental science in several active research areas outside of atomic physics, including chemical physics, quantum information, and quantum control. Beyond these scientific connections and associated applications, the greatest near-term societal benefit of the project has been the education of the participating post-doctoral researchers, as well as graduate, undergraduate, and high-school students students. These young scientists gained valuable experience with state-of-the-art laser equipment and techniques as well as training in scientific ethics and methodology. They developed written and oral presentation skills, and traveled to conferences where they presented and defended their results while establishing professional contacts. They participated in group meetings and developed group problem solving skills in the laboratory. Moreover, their interactions with chemistry and engineering students, postdocs, and faculty in a shared multi-disciplinary laser laboratory provided opportunities to learn about laboratory techniques used in other disciplines, as well differences in scientific cultures, language and terminology. These young women and men are the next generation of scientists and engineers. Their experiences with the project will enable them to contribute to laser, photonics, and other industries; develop new technologies for national defense and security applications; and/or educate another generation of scientists and engineers.
