Donor-acceptor energy transfer involving classical and quantum light in the presence of photonic and plasmonic structures

Overview: This proposal is concerned with the development of theory that describes the transfer of energy between molecules (or other emitters and absorbers) in the presence of plasmonic nanoparticles (Ag,Au,Al, etc), or involving nanoparticle arrays or other complex electromagnetic environments. This transfer involves generating photons as virtual intermediates, and both classical or quantum light are considered in developing the theory, where the latter includes energy transfer involving entangled photons. The research builds on the past history of Förster theory and its extensions for describing resonant energy transfer, but here adapted to problems at the leading edge of science, in which the transfer is mediated by plasmons or other excitations, can extend over distances from 10s of nm to mm, involves strong coupling where traditional perturbation theory approaches can break down, and where quantum effects provide new opportunities for making fundamental changes to the energy transfer process. Intellectual Merit: The proposed work involves fundamental theory development, as this research area is a relatively new field where analytical theory development is needed, but the research will also pursue computational algorithms for using the theory, and applications of the theory to describe experiments done by experimental collaborators. The theories to be developed include the description of: (1) D-A energy transfer near arrays of plasmonic nanoparticles where energy transfer can be mediated by lattice plasmon polariton resonances associated with the arrays, and where issues of superradiance and strong coupling can be tuned by controlling array structural parameters and emitter/absorber concentrations; (2) energy transfer mediated by individual or a few nanoparticles where we want to develop a full quantum electrodynamics formalism that incorporates plasmonic, excitonic and electromagnetic states on equal footing and which will provide the capability of describing quantum effects in which strong coupling leads to the breakdown of perturbation-theory based energy transfer theory; (3) energy transfer mediated by entangled photons that are coupled to entangled plasmons, and including D-A energy transfer in which interference between the two entangled photons modulates the rate. In addition, (4) we will collaborate with several experimentalists in the field who are studying problems related to plasmon-mediated D-A energy transfer involving structures where the donor, acceptor and nanoparticles are organized via DNA origami, or that involve plasmonic arrays with unique optical cavity features; and studies of energy transfer involving entangled interfering photons from parametric down-conversion and other sources. Broader Impacts: The proposed research will lead to an understanding of fundamental science and the development of new computational methods that can be applied in the development of emerging optical technologies where energy transfer between components is important, including topics related to optical switching, in the development of new types of optical devices, in single photon emitters, and in secure communications. There is also the possibility of using the entangled photon studies to probe unusual properties of complex molecules related to two-photon radiative lifetimes and in molecular excited states that serve as virtual intermediates in the two-photon excitation process. The students and postdocs who work on this project, including a significant number of women and minorities, will acquire unique skills that