Imaginary Gauge Potentials in a Non-Hermitian Spin-Orbit Coupled Quantum Gas

Area of Science:

• Quantum physics
• Condensed matter physics
• Topological systems

Background:

• Non-Hermitian systems exhibit unique topological properties.
• Previous models were lattice-based, lacking continuum analogs.
• Imaginary gauge potentials are key to non-Hermitian topological phenomena.

Purpose of the Study:

• To experimentally realize a continuum analog of the Hatano-Nelson model.
• To investigate non-Hermitian physics in a Bose-Einstein condensate (BEC).
• To explore nonreciprocal transport and edge state formation in this system.

Main Methods:

• Utilizing a homogeneous spin-orbit coupled BEC.
• Introducing non-Hermiticity via tunable spin-dependent loss.
• Employing microwave coupling to a subspace with spontaneous emission.
• Analyzing Heisenberg equations of motion and comparing with master equation treatment.

Main Results:

• Observed collective nonreciprocal transport and self-acceleration in real space.
• Demonstrated self-acceleration dependence on BEC spatial extent.
• Found that strong interactions suppress topological edge states, forming localized excited states.
• Confirmed the validity of the non-Hermitian description.

Conclusions:

• The experimental setup successfully realizes a continuum non-Hermitian topological analog.
• The interplay of self-acceleration and interactions governs state localization.
• This work provides a platform for studying non-Hermitian quantum dynamics.