Domain-wall dynamics in Bose-Einstein condensates with synthetic gauge fields

Interactions in many-body physical systems, from condensed matter to high-energy physics,lead to the emergence of exotic particles. Examples are mesons in quantum chromodynamics and composite fermions in fractional quantum Hall systems, which arise from the dynamical coupling between matter and gauge fields(1,2). The challenge of understanding the complexity of matter-gauge interaction can be aided by quantum simulations, for which ultracold atoms offer a versatile platform via the creation of artificial gauge fields. An important step towards simulating the physics of exotic emergent particles is the synthesis of artificial gauge fields whose state depends dynamically on the presence of matter. Here we demonstrate deterministic formation of domain walls in a stable Bose-Einstein condensate with a gauge field that is determined by the atomic density. The density-dependent gauge field is created by simultaneous modulations of an optical lattice potential and interatomic interactions, and results in domains of atoms condensed into two different momenta. Modelling the domain walls as elementary excitations, we find that the domain walls respond to synthetic electric field with a charge-to-mass ratio larger than and opposite to that of the bare atoms. Our workoffers promising prospects to simulate the dynamics and interactions of previously undescribed excitations in quantum systems with dynamical gauge fields.

Automated summary

Interactions in many-body physical systems lead to the emergence of exotic particles. Quantum simulations using ultracold atoms and artificial gauge fields offer a versatile platform to study the complexity of matter-gauge interaction. Researchers have demonstrated the deterministic formation of domain walls in a stable Bose-Einstein condensate, where the gauge field is determined by the atomic density. The domain walls have a unique response to synthetic electric fields with a special charge-to-mass ratio.