Generation of Enhanced Three-Mode Continuously Variable Entanglement

The generation of enhanced three-mode continuously variable (CV) entanglement via difference-frequency amplification in an optical cavity above the threshold is investigated. The quantum entanglement characteristics among the pump, signal, and idler beams are demonstrated by applying a sufficient inseparability criterion for CV entanglement proposed by van Loock and Furusawa. Bright three-mode CV entanglement with different frequencies can be generated in this simple system when the optical cavity operates above its threshold, and the best three-mode CV entanglement can be obtained when the pump threshold parameter is modulated at about σ=1.3.