Quantum Many-Body Physics in Spin-Orbit Coupled Bose Gases

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General audience abstract:Many technologically important material properties, such as the conductivity of metals, can be understood by studying the behavior of a single particle (e.g. an electron) in the material. However, some novel material properties, such as superconductivity and magnetism, depend on how particles interact with one another. When such interparticle interactions are strong, intriguing properties that cannot be explained by the single-particle picture may emerge. In addition, spin-orbit coupling (SOC) - the interaction between a particle’s spin and its motion - plays a crucial role in a wide range of phenomena. The interplay between interparticle interactions and SOC may lead to new quantum materials which hold promise for advanced technologies such as topological quantum computers and dissipationless electronics. Directly studying such materials can be challenging because of imperfections and the lack of experimental controllability. This project aims to build a highly controllable quantum simulator based on atomic Bose gases to explore novel strongly correlated quantum phenomena induced by the interplay between interactions and SOC/gauge fields in low-dimensional quantum fluids. The aim is to provide useful insights for designing new materials and inventing new quantum devices. This project will enhance collaborations between the experimental group doing this work and theorists in the field. Further, the project will integrate research with the education of graduate and undergraduate students from both physics and engineering. These students will learn in an interdisciplinary environment and acquire knowledge and skills in such areas as atomic/molecular/optical physics, condensed matter physics, quantum physics, photonics and electronics. Technical audience abstract:The experimental team will engineer an atomic (Rb-87) Bose gas subjected to synthetic gauge fields and effective spin orbit coupling (SOC) (optically generated using Raman coupling) in novel geometries based on optical lattices (periodic potentials created by lasers) and synthetic spaces (constructed using internal states of atoms). The presence of the lattices can confine atoms in low dimensional geometries with controllable inter-particle interactions and correlations, allowing for studying novel quantum many-body physics induced by the interplay between interactions and synthetic gauge fields. One main direction of the project is to study atoms subjected to gauge fields in spaces with nontrivial geometries, and to explore novel physics inherent to such spaces. For example, engineering a synthetic magnetic field threading a synthetic cylindrical surface realizes a synthetic Hall cylinder where a lattice with a symmetry-protected topological band structure emerges. The program will study the effects of interactions on such topological bands and associated quantum transport, dynamics and phase transitions. Such a Bose gas can be further prepared in real-space 1D tubes which allow for enhanced and tunable inter-particle interactions. As another example, the team aims to prepare a Bose gas with 1D SOC along the 1D tubes, where the exact match of the dimension of both the real space and SOC would notably increase the effects of 1D SOC and also enhance the quantum fluctuations in 1D, leading to new many-body phenomena. The interplay between SOC and tunable inter-particle interactions is theoretically predicted to modify the well-known Tonks-Luttinger physics, giving rise to e.g. non-Luttinger quantum liquids. This program is not only interesting for cold atom research, but is also relevant for condensed matter physics, such as insights to interacting topological physics/superfluids and novel strongly correlated quantum matter in low dimensions.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.