Optical Schr'odinger Cat States in One Mode and two Coupled-Modes Subject to Environments

摘要

Taking the decoherence into account, we investigate nonclassical features ofthe optical Schr\"odinger cat states in one mode and two coupled-modes systemswith two-photon driving. In the one mode system, the relationship between theSchr\"odinger cat states and the system parameters is derived. We observe thatin the presence of single-photon decay the steady states would be a mixture ofSchr\"odinger cats. The dynamics and steady states of such a cat versussingle-photon decay are examined. In the two coupled-modes cases with linearand nonlinear couplings, the dynamics of entanglement and mutual informationare examined with two different initial states and single-photon decay.Compared to the linear coupling case, more complicated structure appears in theWigner function in the nonlinear coupling case. The joint quadraturedistributions are also explored. Such nonclassical states can be used not onlyin exploring the boundary between the classical and the quantum worlds but alsoin quantum metrology and quantum information processing.