Two-Color Quantum Correlation between Down-Conversion Beams at 1.5 and 3.3 μm from a Singly Resonant Optical Parametric Oscillator

Dandan Nie,Kuanshou Zhang,Jinxia Feng,Yuanji Li

doi:10.3390/app10082698

Abstract

We demonstrated a two-color quantum correlation between the down-conversion beams with a telecommunication wavelength at 1.5 μm and mid-infrared wavelength at 3.3 μm generated by a singly resonant optical parametric oscillator (SRO) operated above the pump threshold with a magnesium-oxide doped periodically-poled lithium niobate crystal in the cavity. A maximum of 1.8 dB noise reduction of the intensity difference of the twin beams was measured at the analysis frequency of 5 MHz. Based on a theoretical model for the quantum correlation between the twin beams given by a semi-classical approach, the influence of the analysis frequency and pump parameter on the quantum correlation between the twin beams was discussed theoretically and experimentally. The quantum correlation between the twin beams was degraded at the analysis frequencies above 5 MHz due to the limitation of the bandwidth of SRO cavity and was degraded at the analysis frequencies below 5 MHz due to the excess intensity noise of the pump. The two-color quantum correlated twin beams at 1.5 and 3.3 μm have potential applications in high-precision measurements beyond the shot noise level.

Highlights

Continuous wave (CW) light beams that exhibit nonclassical statistics and quantum correlation are of interest for fundamental tests of quantum physics, and potential applications including high-precision measurements beyond the shot-noise level (SNL) and quantum information such as quantum key distribution and quantum teleportation [1,2,3,4,5,6]
In 1987, the quantum correlated twin beams generated by optical parametric oscillator (OPO) was firstly proposed [7], and the intensity difference fluctuations of the twin beams below the corresponding SNL was experimentally observed [8]
When the pump power was 7.96 W, the singly resonant optical parametric oscillator (SRO) was operated above the threshold

Summary

Introduction

Continuous wave (CW) light beams that exhibit nonclassical statistics and quantum correlation are of interest for fundamental tests of quantum physics, and potential applications including high-precision measurements beyond the shot-noise level (SNL) and quantum information such as quantum key distribution and quantum teleportation [1,2,3,4,5,6]. The common method to generate quantum correlated light beams is using an optical parametric oscillator (OPO) with a nonlinear crystal in the cavity [7,8,9,10,11,12]. With the help of high-quality nonlinear crystals, high-level quantum correlations between down-conversion beams from OPO could be obtained [9,10,11,12]. In these studies, the frequencies of quantum-correlated twin beams (the signal and idler beams) were degenerate, and polarizations of that were orthogonal. As a matter of fact, the optical entangled state with different frequencies, which is an essential quantum source for constructing continuous variable (CV) quantum information networks and establishing connections between systems with different natures, consists of two sub-modes with quantum

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Conclusion