We also present the results of purity in Sec. IV of the Supporting Information. The population and coherence are obtained by performing exact quantum dynamics simulation using the HEOM method. The system Hamiltonian Ĥs is represented in the single excitation subspace (Eq. 8), and the bath and system-bath part Ĥb + Ĥsb are described by the spectral density (Eq. 5). The details of the simulations are provided in Sec. III of the Supporting Information.