Anisotropic Superfluid Behavior of a Dipolar Bose-Einstein Condensate

Area of Science:

• Quantum physics
• Condensed matter physics
• Ultracold atomic gases

Background:

• Superfluidity describes frictionless flow, a quantum mechanical phenomenon.
• Dipolar Bose-Einstein condensates (BECs) exhibit unique properties due to long-range dipole-dipole interactions.
• Understanding transport properties in superfluids is crucial for quantum technologies.

Purpose of the Study:

• To investigate the effect of strong magnetic dipole-dipole interactions on superfluid transport.
• To explore the anisotropy of critical velocity in a dipolar superfluid.
• To connect macroscopic transport properties to the underlying excitation spectrum.

Main Methods:

• Transport measurements using an attractive laser beam moving through a Bose-Einstein condensate of $^{162}$Dy.
• Observation of superfluid flow anisotropy.
• Analysis of heating rates above critical velocity.
• Comparison with simulations based on the Gross-Pitaevskii equation.

Main Results:

• Observed anisotropic superfluid flow in the dipolar condensate.
• Identified an anisotropic critical velocity for the breakdown of dissipationless flow.
• Demonstrated that heating rates above the critical velocity also exhibit anisotropy.
• Found excellent agreement between experimental observations and Gross-Pitaevskii equation simulations.

Conclusions:

• Dipolar interactions significantly influence macroscopic transport properties in superfluids.
• The observed anisotropy in critical velocity is linked to the anisotropy of the dipolar excitation spectrum.
• Dissipationless flow and heating in this system are rendered anisotropic by dipole-dipole interactions.