Collective photon emission in solid state environments: Concatenating non-markovian and markovian dynamics

Collective light emission and multi-qubit dynamics of solid-state quantum emitters are affected both by their coupling to the light field and to lattice vibrations. The effect of phonons on quantum emitters is twofold: polaron formation is described by ultrafast non-markovian dynamics, while slower dephasing is well described by exponential decay. Of the two temperature-dependent processes, the effect of the former on the collective emission and the entanglement decay of emitters is usually not modeled, and also the latter is sometimes neglected. Here we propose and compare two methods that are efficient also for several emitters: the first method concatenates the fast and slow phonon dynamics, and the second is the polaron method. For a single quantum emitter, we show that the dynamical equations are identical in both methods, while predictions for two or more emitters also agree very well. Both of our methods incorporate non-markovian dynamics due to phonons demonstrating the temperature sensitivity of the collective photon emission. Utilizing a simplified markovian model instead may not be accurate enough especially for quantum information applications: for example, we show how the markovian model may considerably overestimate the two-emitter concurrence, except at very low temperatures. Our concatenation and polaron methods can be applied to an arbitrary number and type of quantum emitters, and beyond the bulk GaAs environment that we consider here. Especially the concatenation method can take phonon effects into account at the same computational cost as modelling the emitter-photon interaction alone. Finally, we present approximate analytical expressions for the collective emission spectrum for $N$ emitters on a one-dimensional chain.