Spatially tunable spin interactions with Rydberg atoms in optical tweezers

Abstract

Quantum simulation is a valuable tool for investigating complex quantum systems. It bridges theory and experiment, especially when standard computational methods fail to handle the complexities of strongly correlated many-body scenarios. The effectiveness of quantum simulators arises from their hardware-efficient analog representation of the Hamiltonian under study. Among the emerging platforms, simulators employing Rydberg atoms in optical tweezer arrays are particularly promising. Within this thesis, we detail an experimental platform using single potassium atoms confined within optical tweezer arrays. Interactions between these atoms are induced via excitation to Rydberg states, characterized by high principal quantum numbers. The coupling to Rydberg states can be achieved through direct, resonant excitation or off-resonant Rydberg dressing, where the ground state atom is admixed with a fraction of the Rydberg atom character. In our approach, we trap and cool individual atoms near their motional ground state using Raman sideband cooling. This technique represents an important enhancement in the experiment, thus, making Rydberg dressing feasible, which would otherwise be constrained by thermal broadening. We directly excite the ground state atoms to Rydberg states using a single-photon transition, performed by a laser system that generates up to 1 W of ultra-violet light at 286 nm. This setup facilitates a microscopic study of black-body radiation-induced contaminations of Rydberg states, observed as an avalanche loss process within the atom array. The underlying mechanism for these losses is the dipole-dipole interaction shifts originated by the impu- rities. These shifts render a previously detuned laser resonant with a Rydberg pair state, consequently reducing the experimentally observed dressed state lifetime. Our findings confirm that the interactions catalyze these accelerated excitations. Furthermore, we can tailor interactions for both Ising-type and XYZ-type spin models via off-resonant coupling to Rydberg states when encoding the effective spin-1/2 system within the electronic ground states. This configuration enables us to design spin-spin couplings across the different spin directions determined by the chosen laser parameters. To conclude, our work successfully demonstrates Rydberg dressing experiments within optical tweezer arrays of single potassium atoms. We have studied the underlying processes in the Rydberg dressing regime and validated our ability to tune spin interactions within the array through Rydberg dressing. Overall, our findings underscore the potential of Rydberg dressing in paving the way for advanced Hamiltonian design in analog quantum simulators. untranslated