Experimental investigation of the intensity fluctuation joint probability and conditional distributions of the twin-beam quantum state

Zhang, Yun; Kasai, Katsuyuki; Watanabe, Masayoshi

doi:10.1364/oe.11.000014

Cited by 12 publications

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“…The intensity difference quantum correlations of twin beams were experimentally measured with self-homodyne detectors by different groups and were effectively applied [7][8][9][10][11][12] . However, the phase correlation of the twin beams was not observed for a long time Almost at a parallel period we were also devoting our efforts to measure the quantum entanglement of twin beams from NOPO above threshold.…”

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confidence: 99%

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

Tan

Jia

et al. 2006

Opt. Lett.

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Abstract:The quantum entanglement of amplitude and phase quadratures between two intense optical beams with the total intensity of 22mW and the frequency difference of 1nm, which are produced from an optical parametric oscillator operating above threshold, is experimentally demonstrated with two sets of unbalanced Mach-Zehnder interferometers.The measured quantum correlations of intensity and phase are in reasonable agreement with the results calculated based on a semi-classical analysis of the noise characteristics given by C. Fabre et al. OCIS codes: 190.4410, 270.6570 In recent years quantum information with continuous variables (CV) where f is the noise frequency, S 0 is the shot noise limit (SNL), B and ξ =T/(T+δ) are the cavity bandwidth and the output coupling efficiency of NOPO respectively (T -the transmission coefficient of the output coupling mirror; δ -extra intracavity losses), η is the detection efficiency,is the pump parameter (P -the pump power, P 0 -the threshold pump power of NOPO). The intensity difference quantum correlations of twin beams were experimentally measured with self-homodyne detectors by different groups and were effectively applied [7][8][9][10][11][12] . However, the phase correlation of the twin beams was not observed for a long time Almost at a parallel period we were also devoting our efforts to measure the quantum entanglement of twin beams from NOPO above threshold. The measurement scheme used by us is basically same with that presented by O. Glockl et al. inRef.[15], where they performed sub-shot-noise measurement of the phase quadratures of intense pulsed light 16 . Considering that the phase correlation will be significantly affected by the phase fluctuation of the pump laser 6 and the restricted condition deducing Eqs. (1) and (2) in Ref. [4] requires the finesse of the NOPO cavity for the pump laser much lower than that for the twin beams, in our design the ratio of the cavity finesses for the pump and the twin beams is 16/164 which is much smaller than that in Refs.[13] and [14]. Due to the lower finesse the resonant peak of the pump laser in the cavity is relatively flat and thus the threshold power is higher (~120mW).At first, using a pair of Mach-Zehnder (M-Z) interferometers with unbalanced arm-lengths we detected the amplitude and phase noise of signal and idler output fields from a NOPO above threshold at a certain analysis frequency (20MHz), respectively. Then, the quantum correlations were denoted by the noise levels of the intensity difference and the phase sum of the photocurrents measured by two unbalanced interferometers. wave plate P1 (P2). Rotating the polarization orientation of P1 (P2) we can conveniently switch between phase and amplitude measurements 15 . In our system, the distance difference of two arms ∆L is 7.5m which matches the analysis frequency of 20MHz to make θ=π. The difference of the 5 dc photocurrents of D1 and D2 (D3 and D4) serves as the error signal and is fed back onto the PZT mounted on one of mirrors of the interferometer to...

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confidence: 99%

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

Tan

Jia

et al. 2006

Opt. Lett.

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“…Indeed, the measurements of the frequency spectra of the variances of the output quadrature-phase amplitudes reveal up to 3.7 dB squeezing for NOPA [9], and up to 4.9 dB squeezing for NOPO operating above threshold [18]. However, we remind that our results pertain to the full squeezing of the system and not the spectral component squeezing.…”

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confidence: 56%

Entangled light in transition through the generation threshold

Kryuchkyan

Manukyan

2004

Phys. Rev. A

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We investigate continuous variable entangling resources on the base of two-mode squeezing for all operational regimes of a nondegenerate optical parametric oscillator with allowance for quantum noise of arbitrary level. The results for the quadrature variances of a pair of generated modes are obtained by using the exact steady-state solution of Fokker-Planck equation for the complex Pquasiprobability distribution function. We find a simple expression for the squeezed variances in the near-threshold range and conclude that the maximal two-mode squeezing reaches 50% relative to the level of vacuum fluctuations and is achieved at the pump field intensity close to the generation threshold. The distinction between the degree of two-mode squeezing for monostable and bistable operational regimes is cleared up. [2,3]). An important example provides entangled Einstein-Podolski-Rosen (EPR) state of orthogonally polarized but frequency degenerate beams, efficiently generated via nonlinear optical process of parametric down-conversion. It has been pointed out in [4] and has been demonstrated experimentally in [5] for CV, employing sub-threshold nondegenarate optical parametric oscillator (NOPO). Then a CV entanglement source was built from two independent quadrature squeezed beams combined on a beam-splitter [2]. The generation of CV EPR entanglement using an optical fibre interferometer is also demonstrated [6]. It should be noted that so far most experimental realizations of the CV entanglement on NOPO's have only been operated below threshold. A natural next step is the extension of these investigations to laser-like systems generating entangled bright-light states. Unfortunately, both theoretical and experimental studies of these problems are very complicated and only rare examples are known up to now. Many efforts have been devoted to the study of intensity correlated twin beams from NOPO above threshold [7]. The conditional generation of sub-Poissonian light from bright twin beams in the CV regime is experimentally demonstrated in [8]. Further experimental studies of bright two-mode entangled state from cw nondegenerate optical parametric amplifier have been made in Refs.[9]. The generation of CV polarization entanglement by mixing a pair of polarization squeezed beams is realized * gkryuchk@server.physdep.r.am † leman@ipr.sci.amThe purpose of this paper is to investigate physical properties and the presence of CV entanglement for NOPO in its transition through the generation threshold as well as in the regime of lasing. One of the principal problems in this study is the description of quantum fluctuations. In most theoretical works nonclassical effects and entanglement resources of nonlinear quantum systems are usually described within linear treatment of quantum noise. It is obvious that such approach does not describe the critical ranges (threshold, point of multistability, etc) where the level of quantum noise increases substantially. We use a more adequate approach within the framework of exact nonlinear treatme...

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“…Continuous-wave (CW) Optical Parametric Oscillators (OPOs) are efficient and widely tunable sources of coherent light [1] and nonclassical states [2][3][4][5][6][7][8][9][10][11]. Degenerate cw OPOs have been used to produce single-mode quadrature squeezed light of a single mode [2].…”

Section: Introductionmentioning

confidence: 99%

“…OPOs have been observed in a number of experiments on type II phase matching devices since 1987 [3,4,[6][7][8][9][10][11]. Since then twin beams has been applied to high-sensitivity and quantum nondemolition measurements [12], as well as to high-sensitivity spectroscopy [13,14].…”

Section: Introductionmentioning

confidence: 99%

Single-beam noise characteristics of quantum-correlated twin beams

2004

Self Cite

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Abstract. We investigated the intensity noise spectra of the single beam of a pumpenhanced continuous-wave (cw) optical parametric oscillator (OPO), which was used to generate quantum correlated twin beams, as a function of the pump power. With a triply (pump-, signal-, and idler-) resonant cavity, the oscillation threshold of our OPO was about 8.5±1.3 mW and the measured slope conversion efficiency was 0.72±0.02. A twin beams with power of 240 mW were generated at pump power of 350 mW. The relaxation oscillation frequencies, which depend on the pump power, were observed when the pump power of OPO was from 12.5 mW to 28 mW. The experimental results confirm the predicted increase in OPO relaxation frequency with pump power.Squeezing of the single beam intensity was for the first time inferred experimentally by exploiting nature of quantum noise dependent on loss.

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Experimental investigation of the intensity fluctuation joint probability and conditional distributions of the twin-beam quantum state

Cited by 12 publications

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

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

Entangled light in transition through the generation threshold

Single-beam noise characteristics of quantum-correlated twin beams

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