  In atomically thin semiconductors, localized exciton (X$_L$) coupled to light
shows single quantum emitting behaviors through radiative relaxation processes
providing a new class of optical sources for potential applications in quantum
communication. In most studies, however, X$_L$ photoluminescence (PL) from
crystal defects has mainly been observed in cryogenic conditions because of
their sub-wavelength emission region and low quantum yield at room temperature.
Furthermore, engineering the radiative relaxation properties, e.g., emission
region, intensity, and energy, remained challenging. Here, we present a
plasmonic antenna with a triple-sharp-tips geometry to induce and control the
X$_L$ emission of a WSe$_2$ monolayer (ML) at room temperature. By placing a ML
crystal on the two sharp Au tips in a bowtie antenna fabricated through cascade
domino lithography with a radius of curvature of <1 nm, we effectively induce
tensile strain in the nanoscale region to create robust X$_L$ states. An Au tip
with tip-enhanced photoluminescence (TEPL) spectroscopy is then added to the
strained region to probe and control the X$_L$ emission. With TEPL enhancement
of X$_L$ as high as ~10$^6$ in the triple-sharp-tips device, experimental
results demonstrate the controllable X$_L$ emission in <30 nm area with a PL
energy shift up to 40 meV, resolved by tip-enhanced PL and Raman imaging with
<15 nm spatial resolution. Our approach provides a systematic way to control
localized quantum light in 2D semiconductors offering new strategies for active
quantum nano-optical devices.
