Entanglement generation between two spinor Bose-Einstein condensates with cavity QED

We analyze a scheme for generating entanglement between two spinor Bose-Einstein condensates (BECs). The BECs are off-resonantly coupled to a common photon mode and are controlled by external lasers to induce a $S^z S^z$ interaction, where $S^z$ is the total spin of the BEC. We directly simulate the scheme numerically for small systems and show the performance of the scheme. The scaling of the entanglement to large scale systems under realistic conditions of spontaneous emission and cavity photon loss is analyzed. It is shown that both entanglement in the beyond-continuous variables regime can be generated, where the entanglement is of the order of the maximal entanglement between the systems.