Controlling entanglement by direct quantum feedback

We discuss the generation of entanglement between electronic states of two atoms in a cavity using direct quantum feedback schemes. We compare the effects of different control Hamiltonians and detection processes in the performance of entanglement production and show that the quantum-jump-based feedback proposed by Carvalho and Hope [Phys. Rev. A 76, 010301(R) (2007)] can protect highly entangled states against decoherence. We provide analytical results that explain the robustness of jump feedback, and also analyze the perspectives of experimental implementation by scrutinizing the effects of imperfections and approximations in our model.