2019/10/17 by Weijie Li, Xin Lu, Sudipta Dubey +2 · 1 citation
Physics and Astronomy · #cond-mat.mes-hall
paper · pdf · doi:10.1038/s41563-020-0661-4
arxiv created 2019/10/17 · arxiv updated 2020/06/24
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.