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.