BEGIN:VCALENDAR VERSION:2.0 PRODID:Icfo X-PUBLISHED-TTL:P1W BEGIN:VEVENT UID:69d10da39c879 DTSTART:20220426T080000Z SEQUENCE:0 TRANSP:OPAQUE LOCATION:ICFO Auditorium SUMMARY:ICFO | ANIKA FRÖLIAN CLASS:PUBLIC DESCRIPTION:Ultracold quantum gases constitute a powerful and versatile too l to experimentally explore quantum many-body physics. This thesis present s an original contribution to the quantum simulation of gauge theories wit h ultracold atoms\, which has evolved into a thriving research field durin g the last years. Gauge theories form the basis of our modern understandin g of nature\, with applications ranging from high energy to condensed matt er physics. A subclass formed by topological gauge theories plays a key ro le in the effective description of certain strongly correlated materials. An important example is the fractional quantum Hall effect\, where the top ological Chern-Simons theory can provide an effective single-particle desc ription for some of the filling factors. A simpler toy model which already provides access to the key properties of topological gauge theories is th e one-dimensional chiral BF theory obtained from Chern-Simons theory after dimensional reduction.\n \;\nThis thesis reports on the quantum simul ation of the chiral BF theory in an ultracold gas of bosonic potassium ato ms\, establishing ultracold quantum gases as a resource for the quantum si mulation of topological gauge theories. As a first step\, we establish the theoretical framework necessary for the quantum simulation of the chiral BF theory. We start by deriving an encoded Hamiltonian for this gauge theo ry in which the gauge degrees of freedom are eliminated via the local symm etry constraint. The encoding results in a system with only matter particl es that have local but unconventional chiral interactions. We continue by showing that these chiral interactions can be realized in a Raman-dressed Bose-Einstein condensate (BEC) with unbalanced interactions by deriving an effective single-component Hamiltonian from a microscopic view in momentu m space.\n \;\nSubsequently\, we present the implementation of the dif ferent ingredients necessary to realize the chiral BF theory in our experi ment. In a first series of experiments\, we study the effects of coherent coupling on the effective collisional properties of the system. To this en d\, we employ radio-frequency to couple two internal states with unequal i nteraction in a 39K BEC. We measure the effective scattering length of the system as a function of the coupling field parameters. Moreover\, we use the coherent coupling as an interaction control tool and quench the effect ive interactions from repulsive to attractive values. Afterwards\, we turn to the implementation of Raman coupling and characterize the modification s in the dispersion of Raman-dressed atoms at the single particle level. F inally\, we demonstrate the realization of the chiral BF theory by combini ng Raman coupling and unbalanced interactions in a BEC of 39K. We probe th e chiral interactions arising in the system and observe the formation of c hiral bright solitons which dissolve as soon as their propagation directio n is inverted. Moreover\, we use the local symmetry constraint of the theo ry to reveal the BF electric field through measurements on the matter fiel d alone\, and show that it leads to an asymmetric expansion of the condens ate. Our experiments establish chiral interactions as a novel resource for quantum simulation experiments and pave the way towards implementing topo logical gauge theories in higher dimensions with ultracold atoms.\n \; \nThesis Director: Prof Dr. Leticia Tarruell DTSTAMP:20260404T130955Z END:VEVENT END:VCALENDAR