Three‐Mode Squeezing of Simultaneous and Ordinal Cascaded Four‐Wave Mixing Processes in Rubidium Vapor

Multipartite quantum correlation plays a vital role in potential applications of quantum technologies. In this paper, using energy-level cascaded four-wave mixing (EC-FWM) process, a scheme to produce quantum correlated three-mode light beams within a single device of hot atomic medium of rubidium is proposed. Two- and three-mode amplitude, phase quadrature squeezing and intensity difference squeezing using energy-level simultaneous cascaded FWM (ESC-FWM) method and energy-level ordinal cascaded FWM (EOC-FWM) method, respectively, is theoretically reported. Via investigating their covariance matrix properties, the comparison has been made between the two methods, which shows the ESC-FWM method has a more stable mode structure than EOC-FWM method. Moreover, versatile gain dependent squeezing via EC-FWM is studied and analytical expressions are given. These results show a simplified and efficient experimental scheme producing multipartite quantum correlation among multiple spatially separated beams.