Quantum discord: as a measure of quantumness of correlation between superposed non-degenerate three-level laser and suharmonic cavity light beams

Abstract

This research offers a thorough analysis of the non-classical features associated with cavity radiation produced by a combination of superposed non-degenerate three-level lasers and non-degenerate subharmonic light beams. The Q-functions of the individual light beams are utilized to derive the Q-function for the superposed cavity radiation. From this derived Q-function, we analyze the expectation values of operators. Using the relevant expectation values (correlations) of these operators, we calculate the quantum discord for the superposed cavity light beams being studied. The results indicate that quantum discord increases with the linear gain coefficient and atomic coherence, while it decreases with the parameter \(\gamma \) and population inversion, \(\xi \). Although the trends of forward and backward quantum discord are generally similar, it is distinctly observed that the forward quantum discord is consistently less than the backward quantum discord. The variation in quantum discord observed in the forward and reverse processes is primarily linked to the differences in the mean photon numbers of mode-a and mode-b within the non-degenerate three-level laser system. Additionally, a juxtaposition of quantum discord with entanglement, evaluated through the Logarithmic Negativity criterion, reveals that the quantum discord associated with the superposed cavity radiation remains above the Logarithmic Negativity level. Nonetheless, for certain values of \(\gamma \) exceeding 0.3, quantum discord may fall below the Logarithmic Negativity threshold. This observation underscores the notion that quantum discord is a significant aspect of entanglement. Through the application of quantum discord and the Logarithmic Negativity criterion, it is established that the superposed non-degenerate cavity radiation manifests quantum properties and entanglement.