SAMOP 2023 – wissenschaftliches Programm

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Q: Fachverband Quantenoptik und Photonik

Q 38: Ultra-cold Plasmas and Rydberg Systems I (joint session A/Q)

Q 38.1: Vortrag

Mittwoch, 8. März 2023, 14:30–14:45, F303

Topological phases of Rydberg spin excitations in a honeycomb lattice induced by density-dependent Peierls phases — •Simon Ohler¹, Maximilian Kiefer-Emmanouilidis^{1, 2}, and Michael Fleischhauer¹ — ¹University of Kaiserslautern-Landau, D-67663 Kaiserslautern, Germany — ²German Research Centre for Artificial Intelligence, D-67663 Kaiserslautern, Germany

We show that the nonlinear transport of bosonic excitations in a honeycomb lattice of spin-orbit coupled Rydberg atoms gives rise to disordered quantum phases which are topological and candidates for spin liquids. As demonstrated in [Lienhard et al. Phys. Rev. X, 10, 021031 (2020)] the spin-orbit coupling breaks time-reversal and chiral symmetries and leads to a density-dependent complex hopping of the hard-core bosons or equivalently to complex XY spin interactions. Using exact diagonalization (ED) we investigate the phase diagram resulting from the competition between density-dependent and direct transport. In mean-field there is a transition from a quasi-condensate to a 120^∘-phase when the complex hopping exceeds the direct one. In the full model a new phase with a finite spin gap emerges close to the mean-field critical point due to quantum fluctuations induced by the density-dependence of the hopping. We show that this phase is a genuine disordered one. It has a large spin chirality and a many-body Chern number C=1, which is robust to disorder. ED simulations of small lattices point to a non-degenerate ground state and thus to a bosonic integer-quantum Hall (BIQH) phase, protected by U(1) symmetry.