Compressible Turbulence from Quantum to Classical

A deep understanding of turbulence is required to enable fusion as a source of energy, improve supersonic flight, and explain the formation of elements like gold from supernovae and colliding neutron stars. Despite its importance, many aspects of turbulence are still not well understood, in part due to the difficulty of performing experiments: for example, studying supersonic flow requires expensive wind tunnels, and neutron stars can only indirectly be measured. While efforts are underway to study these systems through NSF funded programs like LIGO, recent advances in cold-atom technology provide a new platform to create turbulence in table-top experiments. For example, superfluid cold atoms have a very low speed of sound, enabling hypersonic flow, and are highly tunable, allowing them to directly model aspects of neutron stars. This project will establish a connection between quantum turbulence in these table-top experiments and important applications that complement ongoing efforts in nuclear physics, nuclear astrophysics, and classical turbulence. The outcomes will not only progress science, but will identify unique quantum features that can be used to advance quantum technologies with future societal benefit similar to how previous advances in cold atom technology produced the precision clocks that enable GPS. This project will explore the relationship between quantum and classical hydrodynamics, addressing questions about the microscopic origins of turbulence, and how the macroscopic hydrodynamics needed to model neutron stars etc. emerge from microscopic physics. Specifically, it will explore how these macroscopic theories emerge after coarse-graining quantum systems, answering questions like: Are the emergent theories classical (i.e. do they flow to a Navier-Stokes-like fixed-point?) or do they retain unique quantum effects that can be exploited for new applications? Methods will be developed for detecting and characterizing quantum turbulence in spite of destructive imaging, and will be validated in close collaboration with experimental groups, exploring new quantum phenomena along the way. These validated methods will then be used to advance nuclear physics such as the origin of pulsar glitches. These investigations require high performance computing and sophisticated data analysis techniques, which will result in open source tools, broadly impacting a variety of related fields, and provide students with the skills needed for successful careers in science. 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.