Bath-Induced and Long-Range Interactions in Disordered Strongly Correlated Optical Lattices

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Disorder, inescapable in nature, can strongly affect the behavior of materials underpinning modern technologies. An urgent problem confronting physics is understanding the interplay of disorder and strong inter-particle interactions in quantum materials. Strong interactions are an ingredient crucial to remarkable phenomena such as high-temperature superconductivity. How interactions and disorder compete or cooperate in these materials to affect superconductivity and give rise to new quantum states is not fully understood. Ultracold atoms trapped in an optical lattice, which is a crystal formed from light, will be used as a model system to study this critical problem. Controllable and completely characterized disorder will be introduced by superimposing optical speckle, which is a laser beam consisting of randomly distributed bright and dark regions. The emergence of different quantum states as the disorder and interactions are independently tuned will be measured. Knowledge gained from this system may lead to a better understanding of high-temperature superconductors and techniques for mitigating the impact of disorder on their performance. The next generation of engineers and scientists will be trained on cutting-edge technologies in laser science, high-frequency microwave electronics, and high-speed computer-controlled signaling.This project builds on previous lattice experiments that discovered a disorder-induced bosonic insulator using Rb-87 atoms and observed a disorder-induced metal-insulator transition using K-40 atoms. Two projects designed to resolve outstanding questions regarding the interplay of strong interactions and disorder in three dimensions will be pursued. First, the impact of a bath on disorder-localized states will be measured using a mixture of Rb-87 hyperfine components trapped in a spin-dependent lattice. Second, the influence of long-range interactions on quantum localization will be investigated using Rydberg dressing of K-40 atoms trapped in a disordered optical lattice. These studies will advance the state-of-the-art in disordered quantum gases, thus enabling new methods for attacking outstanding questions related to condensed matter physics and materials science and enhancing knowledge of strongly correlated systems.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.