Controlling excitons at the nanoscale in semiconductor materials represents a
formidable challenge in the fields of quantum photonics and optoelectronics.
Achieving this control holds great potential for unlocking strong
exciton-exciton interaction regimes, enabling exciton-based logic operations,
exploring exotic quantum phases of matter, facilitating deterministic
positioning and tuning of quantum emitters, and designing advanced
optoelectronic devices. Monolayers of transition metal dichalcogenides (TMDs)
offer inherent two-dimensional confinement and possess significant binding
energies, making them particularly promising candidates for achieving
electric-field-based confinement of excitons without dissociation. While
previous exciton engineering strategies have predominantly focused on local
strain gradients, the recent emergence of electrically confined states in TMDs
has paved the way for novel approaches. Exploiting the valley degree of freedom
associated with these confined states further broadens the prospects for
exciton engineering. Here, we show electric control of light polarization
emitted from one-dimensional (1D) quantum confined states in MoSe2. By
employing non-uniform in-plane electric fields, we demonstrate the in-situ
tuning of the trapping potential and reveal how gate-tunable
valley-hybridization gives rise to linearly polarized emission from these
localized states. Remarkably, the polarization of the localized states can be
entirely engineered through either the spatial geometry of the 1D confinement
potential or the application of an out-of-plane magnetic field