Tunable Continuous-Variable Tripartite Entanglement via Simultaneous and Ordinal Cascaded Nonlinear Processes

Multipartite quantum entanglement plays a vital role in both fundamental science and quantum applications. The cascaded four-wave mixing (FWM) process is an effective method to prepare multipartite entanglement, however, the physical nature of entanglement based on different cascading paths, i.e., simultaneous cascaded FWM (SC-FWM) and ordinal cascaded FWM (OC-FWM), has not yet been conclusively determined. In this article, tunable continuous-variable (CV) triple-mode entanglement is proposed to be generated by using both the SC-FWM and OC-FWM schemes. The simulation results reveal that the absorption/dispersion properties of the two nonlinear processes can be efficiently tuned by varying the optical parameters (i.e., the photon detuning and the nonlinear susceptibility), resulting in triple-mode CV entanglement with tunable properties. Compared with the OC-FWM scheme, the SC-FWM scheme has a broader entanglement bandwidth and a higher degree of entanglement, where the tripartite entanglement region is 4.38% larger than that of the OC-FWM scheme. Furthermore, these results indicate that the SC-FWM scheme has a more compact and stable mode structure with better entanglement performance. Such tunable optical triple-mode entanglement may find applications in specific quantum communication protocols and pave the way for implementing and manipulating multichannel quantum networks.