Quantisation and its breakdown in a Hubbard-Thouless pump

Abstract

Geometric properties of waves and wave functions can explain the appearance of integer-valued observables throughout physics. For example, these 'topological' invariants describe the plateaux observed in the quantised Hall effect and the pumped charge in its dynamic analogon, the Thouless pump. However, the presence of interparticle interactions can profoundly affect the topology of a material, invalidating the idealised formulation in terms of Bloch waves. Despite pioneering experiments in solid state systems, photonic waveguides, and optical lattices, the study of topological insulators under variation of inter-particle interactions has proven challenging. Here, we experimentally realise a topological Thouless pump with tuneable Hubbard interactions in an optical lattice and observe regimes with robust pumping, as well as an interaction-induced breakdown. We confirm the pump's robustness against interactions that are smaller than the protecting gap, which holds true for both repulsive and attractive Hubbard $U$. Furthermore, we identify that bound pairs of fermions are responsible for quantised transport at strongly attractive $U$, supported by measurements of pair fraction and adiabaticity. For strong repulsive interactions, on the contrary, topological pumping breaks down. Yet, we can reinstate quantised pumping by modifying the pump trajectory while starting from the same initial state. Our experiments pave the way for investigating interacting topological insulators, including edge effects and interaction-induced topological phases.

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Cited by in corpus (42)

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• Breakdown of quantization in nonlinear Thouless pumping
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• Floquet-engineered nonlinearities and controllable pair-hopping processes: From optical Kerr cavities to correlated quantum matter
• Floquet engineering of optical nonlinearities: a quantum many-body approach
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• Stabilization of Hubbard-Thouless pumps through nonlocal fermionic repulsion
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• Interaction driven topological phase transitions of hardcore bosons on a two-leg ladder
• Topological pumping induced by spatiotemporal modulation of interaction
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• Splitting and connecting singlets in atomic quantum circuits
• Phase diagram and topology of the XXZ chain with alternating bonds and staggered magnetic field
• Anomalous bulk-edge correspondence of nonlinear Rice-Mele model
• Non-Adiabatic Effect in Topological and Interacting Charge Pumping
• Topological quantum thermometry
• Topological photon pumping in quantum optical systems
• Hong-Ou-Mandel Interference in a temporal-average-inversion-symmetric chain
• Thouless pumping in Josephson junction arrays
• Quasiperiodicity protects quantized transport in disordered systems without gaps
• The anomalous Floquet Anderson insulator in a continuously driven optical lattice
• Fractional Thouless pumping of solitons: a unique manifestation of bulk-edge correspondence of nonlinear eigenvalue problems
• Topologically protected quantized changes of the distance between atoms
• Absence of disordered Thouless pumps at finite frequency
• A spectrum-based shortcut method for topological systems
• Reentrant topology and reverse pumping in a quasiperiodic flux ladder
• Protected quantum gates using qubit doublons in dynamical optical lattices
• Repulsion driven metallic phase in the ground state of the half-filled $t-t^{\prime }$ ionic Hubbard chain
• Inter-species topological phases via a dynamical gauge field
• Quantum theory of fractional topological pumping of lattice solitons
• A symmetry-protected topological optical lattice clock
• Ultracold atomic lattice systems for simulating topological phases: A review
• Galilei covariance of the theory of Thouless pumps
• Anisotropy-driven topological quantum phase transition in magnetic impurities
• A strong-driving toolkit for topological Floquet energy pumps with superconducting circuits
• Optimal control over the full counting statistics in a non-adiabatic pump
• Quantized Acoustoelectric Floquet Effect in Quantum Nanowires