Creating and Probing Multipartite Macroscopic Entanglement with Light

We propose an immediately realizable scheme showing signatures of multipartite entanglement generated by radiation pressure in a cavity system with a movable mirror. We show how the entanglement involving the inaccessible massive object is unraveled by means of field-field quantum correlations and persists within a wide range of working conditions. Our proposal provides an operative way to infer the quantum behavior of a system that is only partially accessible.

Figure 1

The proposed experiment. The fields of two driven cavities $j=a,b$ interact with a movable mirror. Input (output) fields are indicated as ${\widehat{j}}^{\mathrm{in}}$ (${\widehat{j}}^{\mathrm{out}}$), and $\widehat{\xi }$ is responsible for the Brownian motion of the mirror at temperature $T$.

Figure 2

Logarithmic negativity ${\mathcal{E}}_{\mathcal{N}}^{am}$, ${\mathcal{E}}_{\mathcal{N}}^{bm}$, and ${\mathcal{E}}_{\mathcal{N}}^{ab}$ [(a)—(c), respectively] against ${\Delta }_b\in [-3{\omega }_m,0]$ and $P_b\in [0,P_a]$ for the parameters assumed in the text.