Engineering and probing the bosonic Pfaffian quantum Hall state with ultracold atoms in an optical lattice
ORAL
Abstract
Ultracold atoms with synthetic gauge fields provide a powerful platform for quantum simulation of topological matter, including fractional quantum Hall (FQH) phases [1]. Among the most sought-after examples is the Moore–Read (Pfaffian) state, long predicted to host pairing and nontrivial topological order. Here we realize a bosonic Pfaffian with a quasi-hole state of three particles in a 5-by-5 lattice sites system using ultracold 87Rb in an optical lattice subjected to an artificial magnetic field. Starting from a topologically trivial Fock state, we prepare the target FQH state through a sequence of adiabatic ramps, with the protocol design optimized via machine-learning techniques [2].
Using quantum gas microscopy, we directly image hallmark features of the Pfaffian state: a characteristic central density depletion and a pronounced suppression of local three-body correlations g(3) relative to a normal state, providing a microscopic signature of pairing. We also implement a transport-style probe tailored to few-body cold-atom systems: a Hall-drift measurement that tracks the transverse center-of-mass response of the Pfaffian state under a weak applied force [3]. The observed drift shows good qualitative agreement with theory, establishing a proof-of-principle route to extracting Hall response and related transport properties in optical-lattice FQH experiments.
Our work demonstrates a set of new techniques—machine-learning–assisted state preparation combined with site-resolved correlation readout and dynamical Hall-response probing—for engineering and characterizing exotic FQH states in ultracold atoms.
[1] Léonard, J. et al. Realization of a fractional quantum Hall state with ultracold atoms. Nature 619, 495–499 (2023). https://doi.org/10.1038/s41586-023-06122-4
[2] Blatz, T. et al. Bayesian optimization for robust state preparation in quantum many-body systems, Quantum 8, 1388 (2024). https://doi.org/10.22331/q-2024-06-27-1388
[3] Repellin, C., Léonard, J., and Goldman N. Fractional Chern insulators of few bosons in a box: Hall plateaus from center-of-mass drifts and density profiles.” Physical Review A, vol. 102, no. 6 (2020). https://doi.org/10.1103/PhysRevA.102.063316
Using quantum gas microscopy, we directly image hallmark features of the Pfaffian state: a characteristic central density depletion and a pronounced suppression of local three-body correlations g(3) relative to a normal state, providing a microscopic signature of pairing. We also implement a transport-style probe tailored to few-body cold-atom systems: a Hall-drift measurement that tracks the transverse center-of-mass response of the Pfaffian state under a weak applied force [3]. The observed drift shows good qualitative agreement with theory, establishing a proof-of-principle route to extracting Hall response and related transport properties in optical-lattice FQH experiments.
Our work demonstrates a set of new techniques—machine-learning–assisted state preparation combined with site-resolved correlation readout and dynamical Hall-response probing—for engineering and characterizing exotic FQH states in ultracold atoms.
[1] Léonard, J. et al. Realization of a fractional quantum Hall state with ultracold atoms. Nature 619, 495–499 (2023). https://doi.org/10.1038/s41586-023-06122-4
[2] Blatz, T. et al. Bayesian optimization for robust state preparation in quantum many-body systems, Quantum 8, 1388 (2024). https://doi.org/10.22331/q-2024-06-27-1388
[3] Repellin, C., Léonard, J., and Goldman N. Fractional Chern insulators of few bosons in a box: Hall plateaus from center-of-mass drifts and density profiles.” Physical Review A, vol. 102, no. 6 (2020). https://doi.org/10.1103/PhysRevA.102.063316
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Presenters
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Yanfei Li
- Harvard University