A laser can excite electrons at a tiny flaw in diamond or silicon carbide, but the energy does not always return as light. As the defect relaxes toward its lowest-energy, or ground, state, it can emit a photon, move between states with different electron spins, or release energy as vibrations of the surrounding atoms.
These spin defects could serve as stable, readable qubits, the units that hold information in quantum technologies, with potential uses in quantum sensing. Developing them requires understanding that entire cycle of excitation and relaxation. Physicists have used the fundamental equations of quantum mechanics to describe light emission and transitions between different spin states, but predicting energy loss through atomic vibrations, called internal conversion, has been harder.
Researchers at the University of Chicago Pritzker School of Molecular Engineering (UChicago PME) have now developed a computational framework that captures the full optical cycle, including internal conversion. Their study, published in Physical Review Letters, shows how accounting for this process can resolve a long-standing mismatch between predictions and experiments.
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