Generation of dipole squeezing in a two-mode system with entangled coherent states of a quantized electromagnetic field

Two-mode quantized electromagnetic fields can be entangled and admit a large number of coherent states. In this paper, we consider a two-mode system that consists of a two-level atom interacting with a two-mode quantized electromagnetic field, which is initially prepared in an entangled two-mode coherent state, via a nondegenerate two-photon process in a lossless cavity. We study the quantum fluctuations in the two-mode system and investigate in detail the effects of detuning, Stark shift and atomic coherence on atomic dipole squeezing (ADS). We show that ADS strongly depends on the atomic coherence. It is found that the stronger the correlations between the two modes are involved, the more the ADS could be generated. The detuning or Stark shift has a destructive effect on ADS, but the combined effect of the detuning and Stark shift may lead to a regular, periodical and strong ADS pattern.