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Observation of chiral currents with ultracold atoms in bosonic ladders

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Abstract

Engineering optical lattices with laser-induced tunnelling amplitudes has enabled the realization of artificial magnetic fields with remarkable tunability. Here, we report on the observation of chiral Meissner currents in bosonic ladders exposed to a strong artificial magnetic field. By suddenly decoupling the individual ladders and projecting into isolated double wells, we are able to measure the currents on each side of the ladder. For large coupling strengths along the rungs of the ladder, we find a saturated maximum chiral current, which is analogous to the surface currents in the Meissner effect. Below a critical inter-leg coupling strength, the chiral current decreases in good agreement with our expectations for a vortex lattice phase. Our realization of a low-dimensional Meissner-like effect and spin–orbit coupling in one dimension opens the path to exploring interacting particles in low dimensions exposed to a uniform magnetic field.

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Figure 1: Experimental set-up and energy bands.
Figure 2: Phase diagram of ladder currents.
Figure 3: Current measurement.
Figure 4: Chiral current as a function of K/J.
Figure 5: Relative position of the momentum peaks.

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Acknowledgements

We thank S. Nascimbène, Y-A. Chen, D. Hügel and C. Schweizer for stimulating discussions and for sharing their ideas. This work was supported by the DFG (FOR801), NIM and the EU (UQUAM, SIQS). M. Aidelsburger was additionally supported by the Deutsche Telekom Stiftung.

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Contributions

M. Atala, M. Aidelsburger, M.L. and J.T.B. performed the experiment and analysed the data. I.B. and B.P. devised and supervised the project. All authors contributed to the writing of the manuscript.

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Correspondence to Immanuel Bloch.

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The authors declare no competing financial interests.

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Atala, M., Aidelsburger, M., Lohse, M. et al. Observation of chiral currents with ultracold atoms in bosonic ladders. Nature Phys 10, 588–593 (2014). https://doi.org/10.1038/nphys2998

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