When light interacts with matter, its properties ? color and energy, for example ? can be drastically modified. New techniques for manipulating light will enable better solutions to some of today?s biggest challenges, from maximizing efficiency in transforming sunlight into electricity to building faster computers. This project aims to control light at the quantum limit?one particle of light (or photon) at a time?using nanometer-scale metal structures. However, many questions remain about how such nanometer-scale structures affect individual photons. Thus, the first goal of this project is to develop new microscopy methods that will permit the study of light-matter interactions near these metal structures with unprecedented resolution. With this newfound understanding, the second goal is to use the nano-particles to construct the first step towards a quantum computer, which promises an explosion of power and speed in the computers of the future. This project also has broad goals to create space for all students to thrive, regardless of gender, race, and socioeconomic background. This will be achieved, in part, by expanding the scope of the Rensselaer Women in Physics group?s outreach activities to the local elementary and middle schools, and by incorporating diversity education into the physics curriculum. <br/><br/>The potential of quantum information science is fueling demand for the design and generation of new qubits and devices, such as transistors, operating at the single-particle level. Localized surface plasmon resonances in metal nano-particles offer the ability to confine the electromagnetic field to scales well below the diffraction limit of light, and promise the possibility of integratable devices operating at the quantum level. In particular, these plasmon resonances can strongly couple with molecular or semiconductor excitons to form new hybridized states. These states can be used to develop single-photon transistors and other building blocks of a functioning quantum circuit. However, several roadblocks have up to now limited plasmons? practical use. Indeed, although plasmonic modes present the advantage of coupling very strongly to matter, the very small mode volume in plasmonic cavities makes it difficult to get good spatial overlap with single emitters such as quantum dots. This research project proposes to design, develop, and characterize new methods for the fundamental investigation and precise control of the coupling between single quantum emitters and plasmonic nano-cavities. The research objectives include: (1) Developing a new tool to experimentally measure the local density of states using single-molecule super-resolution microscopy, and to understand light-matter interactions in the vicinity of plasmonic nano-structures, beyond what can be learned from simulations of the structure design; (2) Achieving reproducible and controllable coupling between individual quantum emitters and a plasmonic nano-cavity using plasmonic optical trapping; (3) Studying the transition from weak to strong coupling regime in real time and using the strongly coupled system to demonstrate single photon blockade.<br/><br/>This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.