Fluid dynamics: Turbulence in a quantum gas.

Abstract

The discovery of a cascade of sound waves across many wavelengths in an ultracold atomic gas advances our understanding of turbulence in fluids governed by quantum mechanics. See Letter p.72 An important signature of turbulence is the emergence of a cascade of excitations involving all length scales. While turbulence has been observed in quantum fluids—typically liquid helium—it is difficult to control such systems and to observe the properties of turbulence on demand, because the particles therein strongly interact. Here Nir Navon et al. trap a weakly interacting homogeneous Bose–Einstein condensate consisting of rubidium-87 atoms in a cylindrical optical box and shake the gas to produce turbulence. This methodology lets them observe the full turbulent cascade. This work demonstrates that ultracold atomic gases could serve as models for quantum turbulence.