Non-Equilibrium Fermi Gases in a Multi-Region Trap

Lehigh University, Bethlehem PA

Investigators

Abstract

Quantum materials in which electrons interact strongly have unique properties that hold promise for future technologies. Example applications include quantum computing, more efficient electrical power transmission, and improved thermoelectric cooling. In this project, the team will study gases of strongly interacting atoms to better understand the physics of quantum materials. These atoms, like electrons, carry spin, allowing them to mimic the behavior of electrons. At low temperatures, electrons of opposite spin form pairs, leading to superconductivity. However, strongly interacting electrons can also pair above the superconducting transition temperature. A better understanding of this type of pairing may help to explain why some superconductors work at higher temperatures, allowing researchers to design superconductors with higher transition temperatures. The team will use a gas of atoms in a trap made of laser light to study how spin and heat flow between different regions of the trapped atomic gas. These measurements will give insight into pairing and conduction in quantum materials, contributing to ongoing efforts to better understand and design materials for technological applications. Graduate and undergraduate students involved in the project will gain valuable scientific and technical skills that prepare them for careers in quantum science and technology. Strongly interacting fermions lie at the heart of exotic quantum many-body systems, including quantum materials such as high-temperature superconductors, and nuclear systems such as neutron stars. The transport properties of many-body systems determine their dynamics under small deviations from equilibrium. Transport properties also serve as a fundamental tool to characterize many-body systems. This project investigates the transport of spin and coupled spin-heat transport in gases of strongly interacting fermionic atoms. The PI and students will carry out measurements on gases of lithium-6 atoms in a multi-region optical trap. The multi-region trap will enable preparation of non-equilibrium initial spin and density distributions. Removal of the optical barriers between the regions after initialization will allow the system to evolve towards equilibrium. These measurements will provide precise new benchmarks for testing many-body theories, illuminate the nature of the pseudogap in the unitary Fermi gas, and test proposed quantum bounds on transport based on quantum critical scaling laws. 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.