  Electrical control of individual spins and photons in solids is key for
quantum technologies, but scaling down to small, static systems remains
challenging. Here, we demonstrate nanoscale electrical tuning of neutral and
charged excitons in monolayer WSe2 using 1-nm carbon nanotube gates.
Electrostatic simulations reveal a confinement radius below 15 nm, reaching the
exciton Bohr radius limit for few-layer dielectric spacing. In situ
photoluminescence spectroscopy shows gate-controlled conversion between neutral
excitons, negatively charged trions, and biexcitons at 4 K. Important for
quantum information processing applications, our measurements indicate gating
of a local 2D electron gas in the WSe2 layer, coupled to photons via trion
transitions with binding energies exceeding 20 meV. The ability to
deterministically tune and address quantum emitters using nanoscale gates
provides a pathway towards large-scale quantum optoelectronic circuits and
spin-photon interfaces for quantum networking.
