Electrostatic quantum nanocorral for composite charged excitons.

A tunable interface between flying photons and stationary quantum states is important for quantum networks. Quantum-confined charged excitons are attractive in this context because they combine single-photon emission with localized charge states. However, realizing nanoscale electrostatic confinement that is reversible, robust and spectroscopically resolvable remains challenging. Here we show luminous, quantum-confined charged excitons in monolayer WSe2 using an electrostatic quantum nanocorral. A quantum corral was first realized using scanning tunnelling microscopy, where individual adatoms are arranged in a ring on a metal surface to confine electronic standing waves. In our approach, monolayer WSe2 is gated through a nanoporous metallic monolayer less than 1-nm thick, which acts as an electric-field mask and defines confinement on ~10-nm length scales. This geometry creates distinct excitonic quasiparticle states inside and outside the nanopore, with ultrabright charged excitons confined by surrounding higher-energy neutral-exciton states. The resulting confinement produces pronounced energy splittings and clear spectroscopic signatures of discrete centre-of-mass modes. The electrostatic barrier is dynamically reconfigurable, allowing a crossover between zero- and two-dimensional excitonic states, while polarization-resolved measurements reveal signatures of fine-structure splitting. These results establish an electrically tunable route to controlling charged excitons for quantum light sources with adjustable brightness, energy and photon statistics.