Generation of tripartite quantum correlation among amplitude-squeezed beams by frequency doubling in a singly resonant cavity

Abstract

We present a technique for generation of tripartite quantum-correlated amplitude-squeezed light beams, using frequency doubling in a singly resonant cavity with two output ports. The two-output second-harmonic (SH) beams are both nonlinearly coupled to the common fundamental beam even though they have no direct interaction. The nonlinear couphng produces noise reduction of amplitude for each beam and quantum correlations among three beams. In our first experiment, we measured amplitude squeezing of 0.5, 0.8, and 0.6 dB for the fundamental beam and two output SH beams, respectively. Meanwhile, quantum correlation of 0.6 dB between the two amplitude-squeezed SH beams and quantum anticorrelation of 0.6 and 0.8 dB between the squeezed fundamental beam and each of the SH beams were observed around the range of optimum conversion efficiency. This opens an alternate way to produce tripartite-quantum-correlated systems.Continuous wave light beams that exhibit nonclassical statistics and quantum correlation are of interest in studies of quantum mechanics and for a number of applications that include precision measurements beyond the shot-noise limit and quantum information such as quantum communications, quantum key distribution, and quantum teleportation [1-3]. As a matter of fact, the optical Einstein-Podolsky-Rosen entangled state, which is the essential quantum source for implementing continuous variable quantum information, is a two-mode entangled state consisting of two submodes with quantum correlations between both the quadrature amplitude and the quadrature phase [4], Generation and application of bipartite quantum entanglement have been extensively inves tigated both theoretically and experimentally [5][6][7][8][9]. With the development of quantum communication techniques, quantum correlation among more than two parties is going to be the key ingredient for advanced quantum network systems. Especially, the generation of lights with quantum correlation at different frequencies is more important since they are able to link quantum information between communication and storage in the nodes, in which atoms, trapped ions, or fiber windows are employed [10,11].A number of different techniques for the generation of quan tum correlations among multiple beams have been proposed and experimentally implemented. Each of the schemes has its advantages and disadvantages. For example, one of the approaches is to combine independent squeezed states, which are generated from optical parametric oscillators (OPOs), on beam splitters [12,13]. Owing to the availability of high-quality nonlinear material, it is easy to get high-level quantum correla tions. However, it is impossible to generate lights with quantum correlation at different frequencies. Other proposals, such as cascaded nonlinearities, also have this shortcoming [14,15], Recently, it was also demonstrated that a standard triply "zhang® ee.uec.ac.jp PACS number(s): 42.50.Dv, 42.25.-p , 03.67.Ddresonant above-threshold OPO was able to directly produce pump-signal-idler tr...

Tripartite entanglement in a detuned non-degenerate optical parametric oscillator

“…Tripartite entanglement, with the least number of entangled multi-party, is of great significance. Tripartite entanglement can be generated by coupling squeezed beams on beam splitters [4], or directly through nonlinear processes such as optical parametric down-conversion [5][6][7][8][9], second harmonic generation [10][11][12][13] and atomic four-wave mixing [14,15]. Unlike method with beam splitter mixing of the same-frequency modes, direct optical parametric oscillator (OPO) could generate multicolor multipartite entanglement, which has wider applications into quantum internet [16][17][18].…”

Parallel generation of 31 tripartite entangled states based on optical frequency combs

“…[4][5][6] Generally, the continuous-variable (CV) bipartite entanglement can be generated in diverse systems, such as optical parametric amplifier (OPA) or optical parametric oscillator (OPO), [7,8] combination of two squeezed lights with a beam splitter, [9,10] and can be applied in different protocols of quantum communication. [11,12] In recent years, generating CV multipartite entangled states has been widely investigated in diverse methods, such as cascaded nonlinear processes, [13,14] dual-ported frequency doubling process, [15,16] and four-wave mixing process. [17][18][19][20][21] On the one hand, multipartite entangled states with different frequencies, especially including the fiber communication windows and the atomic transition lines, are more practical in applications of quantum communication networks and quantum storage.…”

Quantum information technology applications with squeezing: quantum key distribution and entanglement

“…We have also shown in the previous chapter how initial squeezing affect entanglement between two NV-center ensembles. On the other hand, the generation of tripartite CV entanglement has been demonstrated theoretically [153][154][155][156][157] and experimentally [158,159] among photons as the CV systems, through some nonlinear processes or interactions. However, work on the effect of initial squeezing on the generation of tripartite entanglement via a dynamical process, through some Hamiltonian, has been lacking.…”