While photons in free space barely interact, matter can mediate interactions between them resulting in optical nonlinearities. Such interactions at the single-quantum level result in an on-site photon repulsion, crucial for photon-based quantum information processing and for realizing strongly interacting many-body states of light. Here, we report repulsive dipole-dipole interactions between electric field tuneable, localized interlayer excitons in MoSe2/WSe2 heterobilayer. The presence of a single, localized exciton with an out-of-plane, non-oscillating dipole moment increases the energy of the second excitation by ∼ 2 meV -- an order of magnitude larger than the emission linewidth and corresponding to an inter-dipole distance of ∼ 5 nm. At higher excitation power, multi-exciton complexes appear at systematically higher energies. The magnetic field dependence of the emission polarization is consistent with spin-valley singlet nature of the dipolar molecular state. Our finding is an important step towards the creation of excitonic few- and many-body states such as dipolar crystals with spin-valley spinor in van der Waals (vdW) heterostructures.
@article{arxiv.1910.08139,
title = {Dipolar interactions between field-tuneable, localized emitters in van der Waals heterostructures},
author = {Weijie Li and Xin Lu and Sudipta Dubey and Luka Devenica and Ajit Srivastava},
journal= {arXiv preprint arXiv:1910.08139},
year = {2020}
}