  We study the quantum-mechanical effects arising in a single semiconductor
core/shell quantum dot controllably sandwiched between two plasmonic nanorods.
Control over the position and the sandwich confinement structure is achieved by
the use of a linear-trap, liquid-crystal line defect and laser tweezers that
push the sandwich together. This arrangement allows for the study of exciton
plasmon interactions in a single structure, unaltered by ensemble effects or
the complexity of dielectric interfaces. We demonstrate the effect of plasmonic
confinement on the photon-antibunching behavior of the quantum dot and its
luminescence lifetime. The quantum dot behaves as a single emitter when
nanorods are far away from the quantum dot but shows possible multiexciton
emission and a significantly decreased lifetime when tightly confined in a
plasmonic sandwich. These findings demonstrate that liquid crystal defects,
combined with laser tweezers, enable a versatile platform to study plasmonic
coupling phenomena in a nanoscale laboratory, where all elements can be
arranged almost at will.
