Experiment towards continuous-variable entanglement swapping: Highly correlated four-partite quantum state

Abstract

We present a protocol for performing entanglement swapping with intense pulsed beams. In a first step, the generation of amplitude correlations between two systems that have never interacted directly is demonstrated. This is verified in direct detection with electronic modulation of the detected photocurrents. The measured correlations are better than expected from a classical reconstruction scheme. In an entanglement swapping process, a four-partite entangled state is generated. We prove experimentally that the amplitudes of the four optical modes are quantum correlated 3 dB below shot noise, which is consistent with the presence of genuine four-party entanglement.

The Balance of Quantum Correlations for a Class of Feasible Tripartite Continuous Variable States

“…Fully inseparable three-mode Gaussian states 8,9,10 have been proposed to realize cloning at distance 11,12 , and experimental schemes to generate multimode CV entangled states have been already suggested and demonstrated 13,14,15,16,17,18,19 . More recently, more general quantum correlations in bipartite Gaussian states have been analyzed: Gaussian quantum discord has been introduced 20,21 and experimentally investigated 22,23,24 .…”

Quantum Entanglement Concentration Based on Nonlinear Optics for Quantum Communications

“…Experimental schemes to generate these W states have been already proposed [62][63][64][65]. It has been proven that the W state is robust to decoherence in the noisy environment [66][67][68], and it displays an effective all-versus-nothing nonlocality, as the number of N delocalizations of the single particle goes up [69].…”

Interaction induced photon-number entangled temporal soliton pairs

“…In addition to the generation of squeezed states by the parametric down-conversion in a sub-threshold optical parametric oscillator [1], one can also generate squeezed states by using optical solitons in nonlinear optical fibers [3]. By utilizing the continuous EPR-like correlations of optical beams, one can also realize quantum key distribution [4] and entanglement swapping [5].…”

“…In addition to the generation of squeezed states by the parametric down-conversion in a sub-threshold optical parametric oscillator [1], one can also generate squeezed states by using optical solitons in nonlinear optical fibers [3]. By utilizing the continuous EPR-like correlations of optical beams, one can also realize quantum key distribution [4] and entanglement swapping [5].In this paper, we propose a simple scheme for generating continuous variable entangled states without using beam splitters, but through the nonlinear interaction between two temporal solitons. The quantum interaction of the two solitons is described by the quantum Nonlinear Schrödinger Equation (NSE) and the corresponding photon-number quantum correlations can be calculated.…”