Topology of quantum coherence in singlet fission: Mapping out spin micro-states in quasi-classical nonadiabatic simulations.

Quantum coherence plays an important role in exciton dynamics such as singlet fission, which may be determined by molecular physical properties, including energy levels, electronic couplings, and electron-phonon couplings, and by geometric properties, including packing configuration and exciton delocalization. However, the global picture of quantum coherence in high-dimensional multistate systems is still blurred. Here, we perform nonadiabatic molecular dynamics simulation for singlet fission in tetracene clusters and demonstrate that the topology of quantum coherence in terms of the global structure of the coupled multistate system may significantly modulate fission dynamics. In particular, quantum coherence in the spin-specified models could be protected by its topological structure from external perturbations. Our work suggests that the topology of quantum coherence is indispensable in the understanding and control of quantum dynamics, which may find potential implementations to singlet fission and quantum computation.