Macromolecular Tools for Quantum Information Science

Quantum information science (QIS) is an emerging interdisciplinary paradigm that promises to change the way we think about and execute computations, measure physical properties, communicate securely, and sense stimuli. The fundamental building block of this revolution is the quantum bit (qubit), which at its most essential is a two-level quantum system that can be placed into a coherent superposition of both states. Electron spin-based qubits have emerged as a leading platform for implementation of quantum computing algorithms, single-molecule sensing, and nanoscale metrology. Molecular electron spin qubits based on coordination complexes and organic radicals feature optical, magnetic, and quantum coherence properties that are easily tuned by synthetic modifications. This customizability will permit them to surpass defect-based systems for quantum sensing applications by design of selective and orthogonal sensing and readout mechanisms tailored to each task. These electron spin states, however, are extremely sensitive to magnetic noise in their environments from other unpaired electron spins, molecular motions relative to external fields, and nearby nuclear spins. To move these molecular qubit candidates from solution to application, three outstanding challenges need to be overcome while protecting the quantum behavior of molecular qubits: separation from one another in the intended state, orientation with respect to external stimuli, and precise localization with sub-nanometer resolution. Many mature strategies in nanoscience address these issues with block copolymers, dendrimers, or nanoparticles, but would create abundant magnetic noise in the form of plentiful nuclear spins these structures usually feature. Nuclear spin free polymers are virtually unknown, but by filling that synthetic gap we could apply the fine control of these strategies without compromising the precisely engineered properties of molecular qubits. These tools would enable the creation of bottom-up synthesized nanoscale qubits poised for integration into targetable dendrimer quantum biosensors and devices based on precise multi-qubit assemblies. I propose to synthesize a new class of nuclear-spin-free (NSF) polymer materials to address these challenges. My specific aims are: 1. To synthesize the first NSF organic polymers based on C, O, Si, and S and identify promising lead materials with desirable physical properties for qubit integration 2. To integrate molecular qubits into macromolecular NSF systems by a. studying the impact of polymer structure on qubits dispersed in NSF polymers b. grafting qubits onto NSF polymers to direct molecular qubit assembly 3. To transform molecular qubits into engineered nanoscale objects by constructing 3D NSF dendrimer shells around molecular qubit cores.