Decoherence-induced cross-Kerr nonlinearity for quantum entanglement

Abstract

In this paper, we show that the cross-Kerr nonlinearity is induced by the ground-state decoherence in a Λ system even under the exact one- and two-photon resonance conditions, which is attributed to the fact that the dark-state resonance is broken slightly. By adiabatically eliminating the atomic variables, we find that the decoherence results in a frequency shift of cavity detuning and the two cavity fields experience cross-Kerr nonlinearity by choosing appropriate parameters. As a consequence, the internal nonlinear effects are responsible for the generation of light entanglement, which is verified by our numerical results. The present scheme demonstrates that the decoherence plays a positive role in controlling quantum entanglement, which may be useful for quantum information processing.