Realizing a one-dimensional topological gauge theory in an optically dressed Bose-Einstein condensate

Prof. Leticia Tarruell
ICFO - Ultracold Quantum Gases Group
Mediterranean Technology Park
Av. Carl Friedrich Gauss, 3
08860 Castelldefels (Barcelona), Spain

Quantum gases constitute a versatile testbed for exploring the behavior of quantum matter subjected to electric and magnetic fields. While most experiments consider classical gauge fields that act as a 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 constraints. In my talk, I will discuss our recent realization of the chiral BF theory: a topological field theory for linear anyons that corresponds to a possible one-dimensional reduction of the Chern-Simons gauge theory effectively describing fractional quantum Hall systems. By using the local symmetry constraint of the theory, we encode the gauge field in terms of the matter field. The result is a system with chiral interactions, which we engineer in a potassium Bose-Einstein condensate by synthesizing optically dressed atomic states with a momentum-dependent scattering length. Theoretically, we show that this system realizes the chiral BF Hamiltonian at the quantum level. Experimentally, we observe the chirality of the interactions, the formation of chiral bright solitons - self-bound states of the matter field that only exist when propagating in one direction ? and exploit the local symmetry constraint of the theory to reveal the BF electric field.