Abstract We present a quantum-state-diffusion equation to characterize the dynamics of a generic atomic system due to the coupling to a leaky cavity mode. As quantum resources, the population, the coherence and even the entanglement of the system would gradually leak out of the cavity. The effect from the leakage of the cavity-mode to the uncontrollable degrees of freedom, e.g. environment, is however not always negative to particular applications of these quantum resources. We investigate the competition between these two mechanisms in the framework of the non-Markovian open-quantum-system dynamics, where the leaky mode serves as a general two-layer bosonic environment. Numerical calculations based on our non-perturbative approach reveal a generation of quantum entanglement in the qubit system due to the coupling to a resonant leaky cavity.
An in-depth theoretical study is carried out to examine the quasideterministic entanglement of two atoms inside a leaky cavity. Two $\ensuremath{\Lambda}$-type three-level atoms, initially in their ground states, may become maximally entangled through the interaction with a single photon. By working out an exact analytic solution, we show that the probability of success depends crucially on the spectral function of the injected photon. With a cavity photon, one can generate a maximally entangled state with a certain probability that is always less than
50 However, for an injected photon with a narrower spectral width, this probability can be significantly increased. In particular, we discover situations in which entanglement can be achieved in a single trial with an almost unit probability.