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Recent progress in engineering topological band structures in optical-lattice systems makes it promising to study fractional Chern insulator states with ultracold atoms. Here we consider a realistic finite system of a few repulsively interacting bosons on a square lattice with magnetic flux and sharp edges, as it can be realized in quantum-gas microscopes. We investigate under which conditions a fractional Chern insulator state corresponding to the Laughlin-like state at filling \nu=1/2 can be stabilized. Using numerical simulations, we also find clear signatures of excitations with fractional charge in response both to static pinning potentials and dynamical flux insertion. Since the compressible edges, which are found to feature chiral currents, can serve as a reservoir, these observations are robust against various system parameters [1]. Meanwhile, we introduce a new way to prepare an topological states of matter, which is based on dynamically tuning box potentials in a sub-box configuration [2]. The scheme, dubbed "cold-atom elevator", consists in preparing a quantum gas in a box-shaped trap, specifically partitioned so as to connect a system of interest to adjustable atomic reservoirs. By properly lifting the elevator, atoms gently leave the reservoirs, hence building up the target quantum many-body state inside the quantum simulator. Moreover, this setting naturally incorporates a vacuum-cleaning scheme that effectively cools down the prepared quantum state, by repeatedly removing hot particles from the system in a highly-controllable manner. The prime assets of the cold-atom elevator lie in its practical simplicity and universality, which are expected to bring the quantum simulation of strongly-correlated quantum matter to a new level.
[1] Botao Wang , Xiaoyu Dong, and André Eckardt, Measurable signatures of bosonic fractional Chern insulator states and their fractional excitations in a quantum gas microscope, SciPost Phys. 12, 095 (2022).
[2] Botao Wang, Monika Aidelsburger, Jean Dalibard, André Eckardt, and Nathan Goldman, The cold-atom elevator: From edge-state injection to the preparation of fractional Chern insulators, Phys. Rev. Lett. 132, 163402 (2024).
Botao Wang is doing his postdoc in the group of Nathan Goldman at Université Libre de Bruxelles (ULB), Brussels. He did his PhD with André Eckardt at Max Planck Institute for the Physics of Complex Systems and Technische Universität Berlin, Germany. His main research topics include Floquet engineering and artificial gauge fields, topology in cold atoms, and dynamical properties of quantum gases.
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