Abstract
Dipolar bosonic gases are currently the focus of intensive research due to their interesting many-body physics in the quantum regime. Their experimental embodiments range from Rydberg atoms to GaAs double quantum wells and van der Waals heterostructures built from transition metal dichalcogenides. Although quantum gases are very dilute, mutual interactions between the particles could lead to exotic many-body phenomena such as Bose–Einstein condensation and high-temperature superfluidity. Here we report the effect of repulsive dipolar interactions on the dynamics of interlayer excitons in the dilute regime. By using spatially and temporally resolved photoluminescence imaging, we observe the dynamics of exciton transport, enabling a direct estimation of exciton mobility. The presence of interactions significantly modifies the diffusive transport of excitons, effectively acting as a source of drift force and enhancing the diffusion coefficient by one order of magnitude. Combining repulsive dipolar interactions with the electrical control of interlayer excitons opens up appealing new perspectives for excitonic devices.
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The data that support the findings of this study are available from the corresponding authors upon reasonable request.
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Acknowledgements
We acknowledge many helpful discussions with A. Delteil as well as D. Unuchek and A. Avsar. The authors acknowledge the help of Z. Benes of EPFL CMI for their help with electron beam lithography. Device preparation was carried out in part in the EPFL Centre of MicroNanotechnology (CMI). This work was financially supported by the European Research Council (grant no. 682332) and the Swiss National Science Foundation (grant nos. 175822, 177007 and 164015). This project has received funding from the European Union’s Horizon 2020 research and innovation programme under grant agreement no. 785219 and 881603 (Graphene Flagship Core 2 and Core 3 phases) as well as support from the CCMX Materials Challenge grant ‘Large area growth of 2D materials for device integration’. K.W. and T.T. acknowledge support from the Elemental Strategy Initiative conducted by the MEXT, Japan (grant no. JPMXP0112101001), and JSPS KAKENHI (grant nos. 19H05790 and JP20H00354).
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Z.S. built the experimental setups, performed the optical measurements and analysed the data with input from A.K. A.K. initiated and supervised the project. A.C. fabricated the device. F.T. worked on device fabrication. J.F.G.M. contributed to the initial stages of setup development. K.W. and T.T. grew the hBN crystals. Z.S. and A.K. wrote the manuscript with input from all the authors.
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Sun, Z., Ciarrocchi, A., Tagarelli, F. et al. Excitonic transport driven by repulsive dipolar interaction in a van der Waals heterostructure. Nat. Photon. 16, 79–85 (2022). https://doi.org/10.1038/s41566-021-00908-6
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DOI: https://doi.org/10.1038/s41566-021-00908-6
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