Realization of a chiral BF theory in an optically dressed Bose-Einstein condensate

Ultracold atoms constitute a versatile testbed for exploring the behaviour of quantum matter subjected to electric and magnetic fields. Whereas, most experiments consider classical gauge fields that act as a simple static background for the atoms, gauge fields appearing in nature are instead quantum dynamical entities that are influenced by the spatial configuration and motion of matter, and that fulfill local symmetry constrains. In this talk, we will discuss the realization of a chiral BF theory in an optically-dressed Bose-Einstein condensate. This gauge theory, initially proposed as a model for linear anyons [1,2], is a one-dimensional reduction of the Chern-Simons theory normally used to describe fractional quantum Hall systems. By using the local symmetry constraint, we encode the gauge field in terms of the matter. The result is a system with chiral interactions, which we engineer by synthesizing optically dressed atomic states with a momentum-dependent scattering length. When this dependence is linear, matter behaves as if minimally coupled to a density-dependent vector potential. We experimentally observe its two main features: the formation of chiral bright solitons - self-bound states of the matter field that only exist when propagating in one direction – and the back-action of matter into the gauge field.

[1] S. J. Benetton-Rabello, Phys. Lett. B 363, 180 (1995)

[2] U. Aglietti, L. Griguolo, R. Jackiw, S.-Y. Pi, and D. Seminara, Phys. Rev. Lett. 77, 4406 (1996)