Experimental demonstration of quantum entanglement between frequency-nondegenerate optical twin beams

Su, Xiaolong; Tan, Anhui; Jia, Xiaojun; Qing, Pan; Xie, Changde; Peng, Kunchi

doi:10.1364/ol.31.001133

Cited by 81 publications

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“…The storage and retrieve of quantum states of light are the important operations realizing QINs and have been experimentally demonstrated based on Cs and Rb atoms by several groups [13][14][15][16][17]. For developing practical CV QIN with both nodes and fiber transmission lines, it is essential to prepare multi-partite entangled states consisting of optical sub-modes at fiber transmission and atomic transition frequencies.Non-degenerate optical parametric oscillators (NOPOs) above the threshold are the most successful devices for producing two-color and multi-color CV entangled optical beams in the achieved experiments of quantum optics [18][19][20][21][22][23]. * kcpeng@sxu.edu.cn Two-color entangled optical beams at different frequency regions have been experimentally prepared by means of abovethreshold NOPOs with various pump lasers and nonlinear crystals [18][19][20][21][22].…”

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“…* kcpeng@sxu.edu.cn Two-color entangled optical beams at different frequency regions have been experimentally prepared by means of abovethreshold NOPOs with various pump lasers and nonlinear crystals [18][19][20][21][22]. Recent years, for satisfying the requirements of the developing QIN the generation schemes of multicolor CV entangled states via intra-cavity nonlinear processes have been theoretically proposed [24][25][26][27].…”

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“…It has been well-proved in Refs. [19,38,39], when the input optical beams only passes through the short arm of the interferometer, which can be completed by aligning the polarization of the input light to the transmission direction of PBS1-3 with the HWP in front of the PBS, the sum and the difference of the photo-currents detected by a pair of D1 and D2, (also D3 and D4, D5 and D6) are the noise power of the amplitude quadrature of the input beam and the corresponding QNL, respectively. If keeping the optical phase difference between the long and the short arms at π/2 + 2kπ (k is an integer) and splitting equally the input optical beam …”

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Experimental Realization of Three-Color Entanglement at Optical Fiber Communication and Atomic Storage Wavelengths

et al. 2012

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Entangled states of light including low-loss optical fiber transmission and atomic resonance frequencies are essential resources for future quantum information network. We present the experimental achievement on the three-color entanglement generation at 852 nm, 1550 nm and 1440 nm wavelengths for optical continuous variables. The entanglement generation system consists of two cascaded non-degenerated optical parametric oscillators (NOPOs). The flexible selectivity of nonlinear crystals in the two NOPOs and the tunable property of NOPO provide large freedom for the frequency selection of three entangled optical beams. The presented system is hopeful to be developed as a practical entangled source used in quantum information networks with atomic storage units and long fiber transmission lines.PACS numbers: 03.67. Bg, 03.67.Mn, 42.65.Yj, 42.50.Dv Entanglement is the most typical quantum feature that has no analogue in classical physics. In the development of modern physics the understanding to the conception and property of entanglement has continually attracted the study interests of both theoretical and experimental physicists [1][2][3]. Especially, it has been demonstrated that quantum entanglement is the most important resource in quantum communication and computation. A lot of endeavor has been paid in preparing various quantum entangled states over past twenty years [4][5][6][7][8][9][10][11]. A variety of bipartite optical continuous variable (CV) entangled states have been generated and applied in different protocols of quantum communication involving two parties [6][7][8]. However, a real quantum information network should be composed of many nodes and channels [9][10][11]. It has been known that the controlled quantum communications only can be achieved under the help of multipartite (more than two parties) entangled states. Based on the use of tripartite CV entangled states the interesting quantum communication experiments, such as controlled dense-coding [9], quantum teleportation network [10] and quantum secret sharing [11] etc., have been achieved. Toward practical applications in the real-world we have to establish quantum information networks (QINs) involving both light and matter atoms, where light is used for communicating among distant nodes consisting of matter atoms [12]. The atomic systems in network nodes serve as the storages of quantum information. The storage and retrieve of quantum states of light are the important operations realizing QINs and have been experimentally demonstrated based on Cs and Rb atoms by several groups [13][14][15][16][17]. For developing practical CV QIN with both nodes and fiber transmission lines, it is essential to prepare multi-partite entangled states consisting of optical sub-modes at fiber transmission and atomic transition frequencies.Non-degenerate optical parametric oscillators (NOPOs) above the threshold are the most successful devices for producing two-color and multi-color CV entangled optical beams in the achieved experiments of quantum optics [18]...

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Experimental Realization of Three-Color Entanglement at Optical Fiber Communication and Atomic Storage Wavelengths

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“…(1) and (2) the SNL of the input light, respectively [15,22]. If splitting the input light equivalently to the two arms of the interferometer and adjusting the phase difference between the two optical beams passing through the short and long arms to π/2, the difference photocurrent corresponds to the phase noise level of the input light and the sum photocurrent stands for the SNL [15,22]. The measured losses of both short and long arms are about 22% which mainly come from the losses of the fiber couplers.…”

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Experimental investigation about the influence of pump phase noise on phase-correlation of output optical fields from a non-degenerate parametric oscillator

et al. 2008

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The influence of the phase fluctuation of the pump laser on the phase-correlation between the signal and idler modes of the output fields from as non-degenerate optical parametric oscillator operating above oscillation threshold was experimentally investigated. The noise spectra of the intensity-difference and the phase-sum of the entangled optical beams were measured with a pair of unbalanced fiber Match-Zehnder interferometers specifically designed. The experimental results proved the previously theoretical prediction and are in reasonable agreement with the calculation based on semiclassical theory involving the phase fluctuation of pump laser.

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“…Squeezing in the intensity difference of the twin beams it produces above-threshold (signal and idler) [1] reached the record value of −9.7 dB [2]. Bipartite continuous variable (CV) entanglement in this system, which requires the observation of phase anticorrelations as well, was only demonstrated very recently [3,4,5]. The parametric process involves three fields, yet the pump field is typically treated as a classical quantity.…”

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Experimental observation of three-color optical quantum correlations

Cassemiro

Villar²,

Valente³

et al. 2007

Opt. Lett.

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Quantum correlations between bright pump, signal, and idler beams produced by an optical parametric oscillator, all with different frequencies, are experimentally demonstrated. We show that the degree of entanglement between signal and idler fields is improved by using information of pump fluctuations. This is the first observation of three-color optical quantum correlations. PACS numbers:Quantum correlations are a signature of nonclassical light generation. The optical parametric oscillator (OPO) is the best-known and most widely used source of such correlations. Squeezing in the intensity difference of the twin beams it produces above-threshold (signal and idler) [1] reached the record value of −9.7 dB [2]. Bipartite continuous variable (CV) entanglement in this system, which requires the observation of phase anticorrelations as well, was only demonstrated very recently [3,4,5]. The parametric process involves three fields, yet the pump field is typically treated as a classical quantity. As an exception, quantum properties of the pump were first measured by Kasai et al. [6]. This arises a natural question: are there quantum correlations between all three fields? An affirmative answer has been recently given by Villar et al. [7], who investigated the problem theoretically. Here, we provide the first experimental affirmative answer by observing triple correlations between quadratures of pump, signal, and idler fields.Beyond the demonstration of nonclassical light features, one should notice that all three fields have different frequencies. The interest of quantum frequency conversion was noticed in the early 1990s [8,9] and opens perspectives for the interaction of light with physical systems having different resonance frequencies. The abovethreshold OPO produces, in general, nondegenerate twin beams and the pump beam has approximately twice their frequencies. Three-color quantum correlations increase the number of physical systems that can be simultaneously investigated. Correlations with the pump can also be used to enhance the bipartite entanglement between the twin beams, as we show below.Quantum correlations should exist between the phase quadrature of the pump field and the sum of phase quadratures of signal and idler fields as a direct consequence of energy conservation ω 0 = ω 1 + ω 2 . Indeed, by relating frequency fluctuations to phase fluctuations, we obtain δφ 0 = δφ 1 + δφ 2 . Indices j ∈ {0, 1, 2} refer to pump, signal and idler fields, respectively. The quadratures are defined through the field annihilation operatorsâ j = exp(iφ j )(p j + iq j ), where φ j is chosen so that q j = 0. When the OPO is detuned from exact * Electronic address: nussen@if.usp.br triple resonance, this phase-phase correlation, Cq 0q+ = δq 0 δq + , is partially transferred to an amplitude-phase correlation, Cp 0q+ = δp 0 δq + , owing to phase noise to amplitude noise conversion [10] inside the OPO cavity [q + ≡ (q 1 +q 2 )/ √ 2]. Our experiment is designed to measure joint fluctuations of a combination ofq + andp 0 and com...

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Experimental demonstration of quantum entanglement between frequency-nondegenerate optical twin beams

Cited by 81 publications

References 19 publications

Experimental Realization of Three-Color Entanglement at Optical Fiber Communication and Atomic Storage Wavelengths

Experimental Realization of Three-Color Entanglement at Optical Fiber Communication and Atomic Storage Wavelengths

Experimental investigation about the influence of pump phase noise on phase-correlation of output optical fields from a non-degenerate parametric oscillator

Experimental observation of three-color optical quantum correlations

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