Synthetic dissipation and cascade fluxes in a turbulent quantum gas.
basic_science · Level V
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- Record sourced from PubMed, PMID 31582522.
- Also identified by DOI 10.1126/science.aau6103.
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Abstract
Scale-invariant fluxes are the defining property of turbulent cascades, but their direct measurement is a challenging experimental problem. Here we perform such a measurement for a direct energy cascade in a turbulent quantum gas. Using a time-periodic force, we inject energy at a large length scale and generate a cascade in a uniformly trapped three-dimensional Bose gas. The adjustable trap depth provides a high-momentum cutoff <i>k</i> <sub>D</sub>, which realizes a synthetic dissipation scale. This gives us direct access to the particle flux across a momentum shell of radius <i>k</i> <sub>D</sub>, and the tunability of <i>k</i> <sub>D</sub> allows for a clear demonstration of the zeroth law of turbulence. Moreover, our time-resolved measurements give unique access to the pre-steady-state dynamics, when the cascade front propagates in momentum space.