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Rydberg exciton–polaritons in a Cu2O microcavity

Abstract

Giant Rydberg excitons with principal quantum numbers as high as n = 25 have been observed in cuprous oxide (Cu2O), a semiconductor in which the exciton diameter can become as large as 1 μm. The giant dimension of these excitons results in excitonic interaction enhancements of orders of magnitude. Rydberg exciton–polaritons, formed by the strong coupling of Rydberg excitons to cavity photons, are a promising route to exploit these interactions and achieve a scalable, strongly correlated solid-state platform. However, the strong coupling of these excitons to cavity photons has remained elusive. Here, by embedding a thin Cu2O crystal into a Fabry–Pérot microcavity, we achieve strong coupling of light to Cu2O Rydberg excitons up to n = 6 and demonstrate the formation of Cu2O Rydberg exciton–polaritons. These results pave the way towards realizing strongly interacting exciton–polaritons and exploring strongly correlated phases of matter using light on a chip.

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Fig. 1: Absorption spectrum and cavity structure.
Fig. 2: Momentum–space spectra.
Fig. 3: Real-space spectra.
Fig. 4: Zero-detuning line profiles and the effective coupling strength.
Fig. 5: Scaling of coupling strength.

Data availability

The research data underpinning this publication can be accessed from University of St Andrews Research Data repository at https://doi.org/10.17630/4f4e4d92-8309-45db-bade-26b147696138.

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Acknowledgements

This work was supported by the EPSRC through grant number EP/S014403/1, by the Royal Society through RGS\R2\192174, by the Carlsberg Foundation through the ‘Semper Ardens’ Research Project QCooL, by the NSF through a grant for ITAMP at Harvard University, by the DFG through SPP1929, and by the Danish National Research Foundation through the Center of Excellence ‘CCQ’ (grant agreement number DNRF156). K.O. acknowledges the EPSRC for PhD studentship support through grant number EP/L015110/1. S.K.R. acknowledges the Carnegie Trust for the Universities of Scotland Research Incentive Grant RIG009823. T.V. acknowledges support through the Australian Research Council Centre of Excellence for Engineered Quantum Systems (CE170100009). V.W. acknowledges support by the NSF through a grant for the Institute for Theoretical Atomic, Molecular, and Optical Physics at Harvard University and the Smithsonian Astrophysical Observatory. We thank J. Keeling for fruitful discussions. We also thank Y. Nanao and EPSRC grant number EP/T023449/1 for the X-ray diffraction measurements.

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Contributions

K.O. polished the sample, performed spectroscopy and analysed the data. S.K.R. deposited DBRs and performed the transfer matrix simulations. V.W. and T.P. developed the theory. T.V. and H.O. supervised the project. H.O. conceived and designed the project. All authors contributed to the writing of the manuscript.

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Correspondence to Hamid Ohadi.

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Nature Materials thanks Na Young Kim and the other, anonymous, reviewer(s) for their contribution to the peer review of this work.

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Supplementary Figs. 1–14, Tables 1 and 2, and discussion sections 1–8.

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Orfanakis, K., Rajendran, S.K., Walther, V. et al. Rydberg exciton–polaritons in a Cu2O microcavity. Nat. Mater. 21, 767–772 (2022). https://doi.org/10.1038/s41563-022-01230-4

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