Gapless topological Fulde-Ferrell superfluidity in spin-orbit coupled Fermi gases

Area of Science:

• Condensed Matter Physics
• Quantum Fluids

Background:

• Topological superfluids are typically characterized by a bulk energy gap and metallic boundary states.
• Understanding exotic superfluid phases is crucial for advancing quantum technologies.

Purpose of the Study:

• To investigate the emergence of a gapless topological superfluid in a two-dimensional spin-orbit coupled Fermi gas.
• To explore the role of inhomogeneous Fulde-Ferrell pairing in creating novel topological states.

Main Methods:

• Theoretical modeling of a two-dimensional Fermi gas with spin-orbit coupling.
• Inclusion of both in-plane and out-of-plane Zeeman fields.
• Analysis of the Fulde-Ferrell pairing order parameter and its impact on the superfluid's properties.

Main Results:

• A gapless, topologically nontrivial superfluid state was identified.
• The Fulde-Ferrell pairing, driven by spin-orbit coupling and in-plane Zeeman field, enables the gapless feature.
• A significant Berezinskii-Kosterlitz-Thouless transition temperature was observed.

Conclusions:

• The study reveals an exotic gapless topological superfluid with potential applications in quantum computing.
• The system exhibits robust Majorana edge modes, protected by its topological nature against disorder.
• This work expands the understanding of topological phases in quantum Fermi gases.