Many-Body Echo, Topological Defects and Long-Range Interactions in Dressed Bose-Einstein Condensates

This research program attempts to explore some of the most intriguing and even counterintuitive predictions in quantum physics: (1) evolution of complex systems described by quantum mechanics is reversible, (2) particles with exotic properties can emerge from an excited quantum field, and (3) interactions and entanglement between distant objects can be mediated by virtual excitations in vacuum. As dynamics of complex quantum systems are frequently intractable by classical computers, this project employs three sets of experiments using ultracold atoms and molecules as a simulation platform to test the predictions, an inspiration originally from physicist Richard Feynman.

Here the ultracold atoms and molecules can be precisely programmed to reproduce the conditions under which the predictions can be tested. A deeper understanding of these phenomena will broaden our understanding of the fundamental laws and the origin of exotic phenomena in the quantum world. The program also embodies an education component that shares the excitement of discoveries in science with URM high school students through the S.M.A.R.T. program and with undergraduate students who will lead and perform independent research in the Undergraduate Research Center of Levitation Science.

Specifically, for the first objective, to test reversibility, a number of “many-body echo” schemes will be developed to reverse the heating of interacting atoms when they are coupled to a time-dependent electromagnetic field. Such heating is generic and detrimental to many quantum material and quantum gas experiments. In such systems, a newly identified symmetry suggests systematic approaches to undo the heating, analogous to spin echo sequences that rephase in NMR experiments.

The second objective is to investigate topological defects in a quantum gas coupled to a synthetic gauge field. Here the gauge field is synthesized by modulations of the potential energy and atomic interactions, and the defects form spontaneously. A full characterization of the defects will be realized by a systematic investigation of their dynamical response to the synthetic fields.

The third effort involves bosonic cesium atoms immersed in a degenerate Fermi gas, which is expected to induce long-range interactions and entanglement between the bosons. A high-resolution imaging and optical projection will be employed to test and quantify the correlations of bosons at length scales greater than the range of direct interactions.

This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.