Observation of topological Bloch-state defects and their merging transition

Abstract

Topological defects in Bloch bands, such as Dirac points in graphene, and their resulting Berry phases play an important role for the electronic dynamics in solid state crystals. Such defects can arise in systems with a two-atomic basis due to the momentum-dependent coupling of the two sublattice states, which gives rise to a pseudo-spin texture. The topological defects appear as vortices in the azimuthal phase of this pseudo-spin texture. Here, we demonstrate a complete measurement of the azimuthal phase in a hexagonal optical lattice employing a versatile method based on time-of-flight imaging after off-resonant lattice modulation. Furthermore we map out the merging transition of the two Dirac points induced by beam imbalance. Our work paves the way to accessing geometric properties in optical lattices also with spin-orbit coupling and interactions.

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• Measuring the Chern number of Hofstadter bands with ultracold bosonic atoms
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• Mapping the Berry Curvature from Semiclassical Dynamics in Optical Lattices
• Bloch state tomography using Wilson lines
• Tomography of band insulators from quench dynamics
• Geometry of Bloch states probed by Stückelberg interferometry
• Merging and alignment of Dirac points in a shaken honeycomb optical lattice
• Breaking inversion symmetry in a state-dependent honeycomb lattice: Artificial graphene with tunable band gap
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Cited by in corpus (27)

• Topological quantum matter with cold atoms
• Measuring topology by dynamics: Chern number from linking number
• Floquet Higher-Order Topological Insulators with Anomalous Dynamical Polarization
• Extracting the quantum metric tensor through periodic driving
• Asymptotic Prethermalization in Periodically Driven Classical Spin Chains
• Reinforcement learning for autonomous preparation of Floquet-engineered states: Inverting the quantum Kapitza oscillator
• Quantum Multicriticality near the Dirac-Semimetal to Band-Insulator Critical Point in Two Dimensions: A Controlled Ascent from One Dimension
• Extended Hubbard model in undoped and doped monolayer and bilayer graphene: Selection rules and organizing principle among competing orders
• Extracting the Quantum Geometric Tensor of an Optical Raman Lattice by Bloch State Tomography
• Steady-state Hall response and quantum geometry of driven-dissipative lattices
• Direct Geometric Probe of Singularities in Band Structure
• Unifying Interacting Nodal Semimetals: A New Route to Strong Coupling
• Disorder in dissipation-induced topological states: Evidence for a different type of localization transition
• Artificial graphenes: Dirac matter beyond condensed matter
• High-precision multiband spectroscopy of ultracold fermions in a nonseparable optical lattice
• Observation of Floquet band topology change in driven ultracold Fermi gases
• Entanglement entropy as an order parameter for strongly coupled nodal line semimetals
• Interferometry of non-Abelian band singularities and Euler class topology
• Measuring the topological phase transition via the single-particle density matrix
• Shear viscosity as a probe of nodal topology
• Enhanced repulsively bound atom pairs in topological optical lattice ladders
• Novel criticality of Dirac fermions in the presence of emergent gauge fields
• Novel criticality of Dirac fermions from lattice symmetry breaking
• Universal Landau-Zener regimes in dynamical topological phase transitions
• Combining machine learning with physics: A framework for tracking and sorting multiple dark solitons
• Dirac points merging and wandering in a model Chern insulator
• Detecting degenerate bands topological invariants in optical lattice