Quantized superfluid vortex rings in the unitary Fermi gas.
In a recent article, Yefsah et al. [Nature (London) 499, 426 (2013)] report the observation of an unusual excitation in an elongated harmonically trapped unitary Fermi gas. After phase imprinting a domain wall, they observe oscillations almost an order of magnitude slower than predicted by any theory of domain walls which they interpret as a "heavy soliton" of inertial mass some 200 times larger than the free fermion mass or 50 times larger than expected for a domain wall. We present compelling evidence that this "soliton" is instead a quantized vortex ring, by showing that the main aspects of the experiment can be naturally explained within the framework of time-dependent superfluid density functional theories.
Department of Physics, University of Washington, Seattle, Washington 98195-1560, USA.
Aurel
A
Bulgac
Department of Physics, University of Washington, Seattle, Washington 98195-1560, USA and Institute for Nuclear Theory, University of Washington, Seattle, Washington 98195-1550, USA and Department of Physics and Astronomy, Washington State University, Pullman, Washington 99164-2814, USA.
Michael McNeil
MM
Forbes
Department of Physics, University of Illinois at Urbana-Champaign, Il 61801-3080, USA.
Michelle M
MM
Kelley
Department of Physics, University of Washington, Seattle, Washington 98195-1560, USA and Pacific Northwest National Laboratory, Richland, Washington 99352, USA.
Kenneth J
KJ
Roche
Department of Physics, University of Washington, Seattle, Washington 98195-1560, USA and Faculty of Physics, Warsaw University of Technology, Ulica Koszykowa 75, 00-662 Warsaw, Poland.
Gabriel
G
Wlazłowski