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Mott insulator of strongly interacting two-dimensional semiconductor excitons

Nature Physics volume 18, pages 149–153 (2022)Cite this article

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Abstract

In condensed-matter physics, Mott insulators are an important phase involving strongly interacting electrons because of their intricate relationship with high-temperature superconductors1,2. Mott phases were recently observed for both bosonic and fermionic species in atomic systems3,4,5,6,7,8,9. However, in the solid state, the fingerprint of a Mott insulator implemented with bosons has yet to be found. Here we demonstrate such signature by exploring the Bose–Hubbard model using semiconductor excitons confined in a two-dimensional lattice. We emphasize the regime where on-site interactions are comparable to the energy separation between lattice-confined states. We then observe that a Mott phase is accessible, with at most two excitons uniformly occupying each lattice site. The technology introduced here allows us to programme the geometry of the lattice that confines the excitons. This versatility, combined with the long-range nature of dipolar interactions between excitons, provides a route to explore many-body phases that spontaneously break the lattice symmetry10,11.

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Fig. 1: Bose–Hubbard physics.
Fig. 2: Arbitrary filling of an 800 nm period lattice.
Fig. 3: Mott-like phases in an 800 nm period lattice.
Fig. 4: Mott insulator in a 400 nm period lattice.

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Acknowledgements

We would like to thank M. Holzmann for his crucial support in calculating microscopically dipolar interactions in the lattice, M. Lewenstein, M. Polini and A. Reserbat-Plantey for a critical reading of our manuscript, together with S. Gasparetto for graphical works. F.D. and C.L. acknowledge the Labex Matisse and IXTASE from the French Agency for Research (ANR-20-CE30-0032-01). The work at Princeton University (L.P. and K.B.) was funded by the Gordon and Betty Moore Foundation through the EPiQS initiative Grant GBMF4420 and by the National Science Foundation MRSEC Grant DMR 1420541.

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Authors and Affiliations

  1. Institut des Nanosciences de Paris, CNRS and Sorbonne Université, Paris, France

    Camille Lagoin & François Dubin

  2. Laboratoire de Materiaux et Phenomenes Quantiques, Université Paris Diderot, Paris, France

    Stephan Suffit

  3. PRISM, Princeton Institute for the Science and Technology of Materials, Princeton University, Princeton, NJ, USA

    Kirk Baldwin & Loren Pfeiffer

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  1. Camille Lagoin
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  2. Stephan Suffit
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  3. Kirk Baldwin
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  4. Loren Pfeiffer
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Contributions

L.P. and K.B. realized the bare semiconductor quantum wells on which C.L., S.S. and F.D. realized the electronic lithography necessary to engineer the final sample with electrostatic lattices. C.L. and F.D. performed the experiments on this sample, analysed the results and wrote the manuscript. F.D. designed the project.

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Correspondence to François Dubin.

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Peer review information Nature Physics thanks the anonymous reviewers for their contribution to the peer review of this work.

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Supplementary Information

Supplementary Figs. S1–S12, Tables 1 and 2 and Sections I to V.

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Raw experimental data for all panels of Fig 4.

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Lagoin, C., Suffit, S., Baldwin, K. et al. Mott insulator of strongly interacting two-dimensional semiconductor excitons. Nat. Phys. 18, 149–153 (2022). https://doi.org/10.1038/s41567-021-01440-8

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