Entanglement of a cavity light produced by a superposed two-mode coherent and subharmonic light

TL;DR

This paper investigates the quantum properties of superposed two-mode coherent and subharmonic cavity light beams, demonstrating their squeezing and entanglement characteristics through quantum Langevin equation solutions and Q-function analysis.

Contribution

It introduces a method to analyze the quantum state, squeezing, and entanglement of superposed two-mode light beams using Q-functions and quantum Langevin equations, revealing their nonclassical properties.

Findings

Superposed two-mode light beams are in a squeezed state with 25% squeezing below vacuum level.

The superposed beams exhibit 75% degree of entanglement at steady state and threshold.

Maximum squeezing and entanglement occur at threshold and steady state conditions.

Abstract

With the aid of the solutions of the Quantum Langevin equations, we have calculated the Q-functions for the two-mode coherent and subharmonic cavity light beams. We have then determined the Q-function for the superposed two-mode coherent and subharmonic cavity light beams. With the help of the pertinent Q-functions for cavity light beams, we determined the photon statistics, quadrature statistics, and entanglement. we have obtained that the superposed two-mode coherent and subharmonic cavity light beams are in a squeezed state and the squeezing occurs in the plus quadrature. Besides, our analysis shows that at steady state and at threshold, the superposed two-mode coherent and subharmonic light beams have a maximum squeezing of $25\%$ below the two-mode vacuum-state level. We have also clearly shown that the superposed two-mode light beam is entangled at steady-state and threshold and the entanglement turned out to be observed in the highly correlated squeezed photons with $75\%$ degree of entanglement.