Microscopy of Ultracold Magnetic Quantum Fluids

Massachusetts Institute Of Technology, Cambridge MA

Investigators

Abstract

Long-range interactions mediate many of the most exciting, but poorly understood, phenomena in nature, driving phenomena as diverse as superconductivity, the structures inside neutron stars, and the physics of the early Universe. They determine the arrangement of water molecule networks coating proteins and the physics of magnetic thin films promising new platforms for computer memory and logic. Competition between different forces drives pattern formation in biology, chemical reactions, collider physics, atmospheric, oceanic, and plasma science. In particular, understanding the consequences of long-range forces in systems governed by quantum mechanics is simultaneously theoretically difficult, and essential for designing new materials which exploit quantum behaviors. In this program, the research team will prepare a gas of magnetic atoms, cooled down to billionths of a degree above absolute zero, and confined into a sheet by precisely sculpted laser beams. This forms a flexible experimental arena to explore and understand the role of long-range magnetic forces, ranging from self-organization into intricate structures, the mechanisms underpinning superfluidity, and the dynamics of individual quanta of circulation inside the fluid. The regime of validity for many existing theories of two-dimensional magnetic gases is unclear, motivating the development of precisely controlled experimental platforms. Cutting-edge quantum gas research entails a combination of optics, quantum physics, computer control, electronics and vacuum hardware. The apparatus is entirely built and run by undergraduates, graduate students, and postdocs. This provides an ideal training for the future quantum workforce, equipping group members to be leaders in both academic and industrial quantum research and development. The PI and his undergraduate and graduate students will employ a gas of highly-magnetic erbium atoms, confined to an oblate geometry via an optical lattice and imaged using a high-resolution microscope objective. This will provide a powerful platform for exploring collective physics mediated by a subtle interplay of short-ranged interactions, long-range anisotropic magnetic forces, kinetic energy, trapping potentials, and quantum fluctuations, leading to a plethora of predicted emergent phases. The research team will investigate the core structure and collective dynamics of quantum vortices, spontaneous pattern formation and density ordering, and the influence of long-range interactions on the superfluid Berezinskii–Kosterlitz–Thouless (BKT) transition. On the one hand, these experiments will constitute a striking qualitative demonstration of long-predicted emergent phases in dipolar fluids. On the other, they will provide essential quantitative benchmarks against which to test our current understanding of the interplay between long-range forces, quantum fluctuations, and reduced dimensionality, and the new phases of matter which emerge. 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.