Quantifying phonon-induced non-Markovianity in color centers in diamond

We propose the application of a coherence-based measure for non-Markovianity to study the dynamics of color centers in diamond, where the optical coherence between two orbital states is affected by interactions with a structured phonon bath. Although limited to pure dephasing, we show that this measure is well behaved at arbitrary temperatures and experimentally accessible through Ramsey spectroscopy. By taking realistic phonon spectral density functions into account, we use this quantity to show how non-Markovianity is affected by the presence of both bulk and quasilocalized phonon modes, as relevant for most defects in solids. Importantly, with only a minor modification the measure can be adapted to study the source of non-Markovianity in driven two-level systems and is thus applicable for a large class of systems modeled by the spin-boson Hamiltonian.