Observation of Nearly Perfect Irrotational Flow in Normal and Superfluid Strongly Interacting Fermi Gases
- Duke University, Department of Physics, Durham, North Carolina, 27708 (United States)
We study the hydrodynamic expansion of a rotating strongly interacting Fermi gas by releasing a cigar-shaped cloud with a known angular momentum from an optical trap. As the aspect ratio of the expanding cloud approaches unity, the angular velocity increases, indicating quenching of the moment of inertia I to as low as 0.05 of the rigid body value I{sub rig}. Remarkably, we observe this behavior in both the superfluid and collisional normal fluid regimes, which obey nearly identical zero-viscosity irrotational hydrodynamics. We attribute irrotational flow in the normal fluid to a decay of the rotational part of the stream velocity during expansion, which occurs when the shear viscosity is negligible. Using conservation of angular momentum, we directly observe a fundamental result of irrotational hydrodynamics, I/I{sub rig}={delta}{sup 2}, where {delta} is the deformation parameter of the cloud.
- OSTI ID:
- 21024221
- Journal Information:
- Physical Review Letters, Vol. 99, Issue 14; Other Information: DOI: 10.1103/PhysRevLett.99.140401; (c) 2007 The American Physical Society; Country of input: International Atomic Energy Agency (IAEA); ISSN 0031-9007
- Country of Publication:
- United States
- Language:
- English
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