Scheme to generate continuous-variable quadripartite entanglement by intracavity down-conversion cascaded with double sum-frequency generations

Abstract

We theoretically show that continuous-variable genuine quadripartite entanglement can be generated by intracavity cascaded nonlinear optical interactions. The process consists of a parametric down-conversion, a sum-frequency generation of pump and signal and a sum-frequency generation of pump and idler. The characteristics of the quadripartite entanglement among the signal, the idler, and two sum-frequency modes are analyzed by applying a sufficient inseparability criterion for multipartite continuous-variable entanglement proposed by Van Loock and Furusawa. The threshold properties of the system are also discussed.

Quadripartite continuous-variable entanglement via quadruply concurrent down-conversion

“…In regards to quadripartite entangled beams, there have been theoretical proposals based on linear optics and cascaded nonlinearites [20][21][22][23]. In this work we build on a tripartite scheme proposed by Bradley et al in [17] but for the case of quadruply concurrent nonlinearities.…”

“…(21)-(23). The below-threshold (solid line) and above-threshold (dashed line) cases are shown for cavity pump amplitudes = 0.8 c and = 1.2 c , respectively.…”

Quadripartite entanglement from coupled type I second harmonic generation

“…Quadripartite entanglement generated from cascaded second-harmonic generation [17] and in an opto-mechanical system are also suggested [18]. However, for quadripartite entanglement, to our knowledge, quasiperiodic optical superlattice is as an important candidate [19,20]. Recently, we suggested a compact scheme to generate bright quadripartite continuous variable entanglement from a nonlinear optical coupler, where two coupled type I parametric down conversions processes are implemented [21].…”

Separated atomic ensembles: Multimode squeezed states and multipartite entangled states

“…Su et al [24] have prepared the quadripartite GHZ entangled states experimentally. The tripartite and quadripartite GHZ entanglements have been studied in the parametric interactions [25][26][27][28] and in the semiconductor [29]. On the other hand, the cluster entangled states are such that in the limit of infinite squeezing, the states become zero eigenstates of a set of quadrature combinations, p i − j ∈N i x j → 0, ∀i ∈ N .…”