Quantized superfluid vortex rings in the unitary Fermi gas.

Area of Science:

• Ultracold atomic gases
• Quantum physics
• Condensed matter physics

Background:

• Yefsah et al. reported unusual oscillations in a harmonically trapped unitary Fermi gas.
• These oscillations were attributed to a "heavy soliton" with significantly increased inertial mass.

Purpose of the Study:

• To re-interpret the experimental observations of Yefsah et al.
• To provide an alternative explanation for the observed "heavy soliton" phenomenon.

Main Methods:

• Analysis of experimental data within the framework of time-dependent superfluid density functional theories.
• Modeling the excitation as a quantized vortex ring.

Main Results:

• The observed oscillations are consistent with the behavior of a quantized vortex ring.
• The quantized vortex ring model naturally explains the "heavy soliton" characteristics.

Conclusions:

• The unusual excitation observed in the unitary Fermi gas is identified as a quantized vortex ring, not a heavy soliton.
• Time-dependent superfluid density functional theories provide a robust framework for understanding these phenomena in trapped Fermi gases.