This proposal describes a theoretical study of important problems in the many body physics of cold atoms and related systems. Building on previous work, the investigator will explore several topical subjects, including (1) properties of a Fermi gas near a Feshbach resonance; (2) spectra of atomic hydrogen on Helium surfaces and embedded in a molecular hydrogen matrix; and (3)dynamics of tuning the interaction strength for atoms trapped in a strong optical lattice. These projects are motivated by (i) interest in fundamental physical properties of cold atoms, (ii) desires to use cold atoms as a model system to understand other many body systems, and (iii) puzzles found in ongoing experiments. Studying cold atoms has impact on many body problems in condensed matter and nuclear physics.
In this project the principle investigator studied the theory of collective effects in ultracold gases, developing new insight into the quantum mechanics of interacting particles. Much of the research focussed on techniques used to experimentally probe these systems. For example, he quantified the accuracy of "time-of-flight expansion," enabling future experiments to make more precise statements about the fundamentals of quantum interactions. Similarly, he analyzed a number of spectroscopic probes, showing how important correlations become encoded. The principle intellectual merit of this line of research comes from learning about the basic rules that govern the world around us. One cannot control what one does not understand. This research project included a number of facets designed to provide broader impact. First, at least four graduate students received extensive training as part of the project. Second, the PI was involved in a number of important educational programs, including national efforts aimed at improving the training of middle/highschool science teachers (PhysTEC) and more general efforts to improve the education of undergraduate physics students in order to better meet national needs(SPIN-UP). He has been part of an outreach programs aimed at a local middle school, and has found ways to help support the outreach efforts of Cornell undergraduate students. Moreover the scientific results from this study (particularly those on pseudogaps) have the potential to broadly influence atomic, nuclear, condensed matter, and astrophysics.
