Bright entanglement in the intracavity nonlinear coupler

We show that the intracavity Kerr nonlinear coupler is a potential source of bright continuous variable entangled light beams which are tunable and spatially separated. We use a linearized fluctuation analysis to calculate the necessary correlations in regimes where it is valid. This means that we are treating regimes where the system exhibits Gaussian statistics so that well-known criteria are both necessary and sufficient to demonstrate entanglement. This system may be realized with integrated optics and thus provides a potentially rugged and stable source of bright entangled beams.

Figure 1

(Color online) The intensity as a function of pump intensity, for $\chi ={10}^{-6}$, $\gamma =1$, and $\Delta =0$, and two different values of the coupling. All quantities shown in this and subsequent figures are dimensionless.

Figure 2

(Color online) Violation of the Duan inequalities for $ϵ={10}^3$, $\gamma =1$, and $J=\Delta =10$. The solid line is for $\chi ={10}^{-5}$, at a quadrature angle of $\theta =80°$, the dashed line is for $\chi ={10}^{-6}$, at an angle of $\theta =122°$, and the dash-dotted line is for $\chi ={10}^{-7}$, at an angle of $\theta =14°$. The inequality is violated and entanglement is demonstrated for any value less than 4.

Figure 3

(Color online) Violation of the EPR inequality for $ϵ={10}^3$, $\gamma =1$, and $J=\Delta =10$. The solid line is for $\chi ={10}^{-5}$, at a quadrature angle of $\theta =80°$, the dashed line is for $\chi ={10}^{-6}$, at an angle of $\theta =122°$, and the dash-dotted line is for $\chi ={10}^{-7}$, at an angle of $\theta =14°$.

Figure 4

(Color online) The logarithmic negativity as a function of frequency for $ϵ={10}^3$, $\gamma =1$, and $J=\Delta =10$. The solid line is for $\chi ={10}^{-5}$, the dashed line is for $\chi ={10}^{-6}$, and the dash-dotted line is for $\chi ={10}^{-7}$.