Solid‐State Quantum Coherence From a High‐Spin Donor–Acceptor Conjugated Polymer

Molecular spin systems that can be chemically tuned, coherently controlled, and readily integrated within devices remain central to the realization of emerging quantum technologies. Organic high-spin materials are prime candidates owing to their similarity in electronic structure to leading solid-state defect-based systems, light element composition, and the potential for entanglement and qubit operations mediated through spin-spin exchange. However, the inherent instability of these species precludes their rational design, development, and application. Here, the first example of an organic high-spin qubit based on a conjugated polymer semiconductor comprised of alternating dithienosilole and thiadiazoloquinoxaline heterocycles is demonstrated. It is shown that electron spins within the macromolecule demonstrate high-fidelity coherent control of the superposition state with room temperature coherence and solid-state relaxation times that are competitive with or exceed other synthetic molecular qubits. These attributes, along with robust stability, chemical tunability, rich interrelated optoelectronic functionalities, and solution processability, offer a fundamentally new approach to integrating quantum phenomena within functional device platforms.