  For quantum information applications utilizing single excitons and spins, the
deterministic placement and control of a single optically driven quantum dot is
a long standing goal. MoSe2-WSe2 heterostructures host spatially indirect
interlayer excitons (IXs) which exhibit significantly longer lifetimes than
monolayer excitons and unique spin-valley physics, making them promising
candidates for quantum information applications. Previous IX trapping
approaches involving moir\'e superlattices and nanopillars do not meet the
requirements for deterministic placement, nanoscale confinement, and energy
tunability. Here, we use a nanopatterned graphene gate to create a sharply
varying electric field in close proximity to a MoSe2-WSe2 heterostructure. The
interaction between the permanent dipole moment of the IX and the electric
field creates a deterministically placed, ~20 nm wide trap for the IXs. The
trapped IXs show the predicted electric field dependent energy, saturation at
low excitation power, and increased lifetime, all signatures of strong spatial
confinement. Our architecture can realize deterministic trapping of single IXs,
which has broad applications to on-chip scalable quantum information processing
based on IX quantum dots.
