Optimizing DNA-assembled dye aggregates for quantum coherent exciton devices

RESEARCH PROBLEM, OBJECTIVES AND TECHNICAL APPROACHES. Exciton delocalization was first observed when dye monomers in solution formed aggregates. Protein-template dye aggregates in natural light harvesting systems have sustained room temperature exciton delocalization and quantum coherence, leading to quantum entangled states and coherent energy transport (theoretically, no energy loss), fueling interest in room temperature quantum computing. However, protein-templated aggregation is challenging as little is known of protein self-assembly design rules (> twenty amino acid building blocks). Conversely, only four nucleic acid building blocks for DNA exist, hence DNA self-assembly is founded in simple and predictable design rules. We at Boise State, and our collaborators at the U.S. Naval Research Laboratory (NRL) have both used DNA self-assembly to template dye aggregates which have exhibited several signatures room temperature exciton delocalization. Building on this effort, our long-term goal is to achieve room temperature molecular excitonic quantum computing based on the rational design of excitonic quantum gates composed of pre-configured dyes templated and organized using nucleic acid self- assembly. PROBLEM. Most other quantum computing approaches may be more mature than our approach, however, they require extreme environments (e.g., milliKelvin temperatures, dry environments, external fields), and top-down approaches to fabricate constructs. In contrast, our constructs operate at room temperature in biological environments (e.g., both wet and dry conditions) and use the bottom-up approach of DNA self-assembly to assemble aggregate structures that have footprints that are ~1000x smaller. While we have demonstrated exciton delocalization at room temperature, the relationships between the structure-properties of dyes that lead to conditions that are conducive to exciton delocalization and quantum coherence have yet to be established. We propose to gain a fundamental understanding of these relationships by examining the influence of dye-structure properties within dye aggregates on key parameters in the Frenkel Hamiltonian that dictate molecular exciton interactions on exciton delocalization, quantum coherence, and coherence lifetimes. With this fundamental knowledge, the path to excitonic quantum computing will be much more well-defined. To acquire this fundamental knowledge, the objectives of NRL and Boise State entail a 4-fold approach: synthesize dyes with specific dye structure-properties, arrange the dyes in specific aggregate configurations using a series of DNA scaffolds, use optical methods to characterize dye aggregates (both ensemble and single structures) for exciton delocalization and quantum coherence, and employ Frenkel exciton theory and computational methods to establish key parameter relationships and guide experiments. ANTICIPATED OUTCOME OF THE RESEARCH. The outcome of the collaborative proposed research between Boise State University and NRL is expected to reveal relationships, and the design rules behind them, between tailored dye structure-properties, dye aggregates, and key parameters in the Frenkel Hamiltonian. These key parameters can be exploited to design and engineer excitonic quantum gates necessary for room temperature quantum computing. IMPACT ON DOD CAPABILITIES. Highlighted in the Department of Navy~s Research, Development, Test & Evaluation plan is a conceptual view of the operational battlespace in 2045. This conceptual view indicates that naval warfighting capabilities will be founded in ~emerging scientific and engineering fields of study in key areas~ including quantum technologies (i.e., quantum computing, quantum sensing, quantum communications), nanotechnology, synthetic biology, energy harvesting, optical computing, and photonics. Our success will advance these emerging DoN key areas by the fundamental knowledge gained in these studies. APPROVED FOR PUBLIC RELEASE.