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

TL;DR

This paper investigates the effects of decoherence on optical Schr"odinger cat states in single and coupled modes, analyzing their dynamics, steady states, and potential applications in quantum technologies.

Contribution

It provides a detailed analysis of how single-photon decay influences the nonclassical features and entanglement in optical Schr"odinger cat states with both linear and nonlinear couplings.

Findings

Steady states become mixtures of Schr"odinger cats under decay.

More complex Wigner function structures appear with nonlinear coupling.

Nonclassical states have potential in quantum metrology and information processing.

Abstract

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