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中国物理学会期刊

光场高阶光子关联的分析与测量

CSTR: 32037.14.aps.69.20200325

Analysis and measurement of high-order photon correlations of light fields

CSTR: 32037.14.aps.69.20200325
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  • 利用双Hanbury Brown-Twiss探测系统理论分析并在实验上精确测量了不同光场的高阶光子关联g(n) (n > 2). 探测系统通过四个单光子计数模块, 探测分析光子时间关联的联合分布概率. 在理论上, 考虑实际探测系统背景噪声和系统效率的影响, 分析研究了热态、相干态、压缩真空态和Fock态的三阶及四阶光子关联的结果, 及其随光场入射光强、压缩参数及光子数的变化. 并在实验中研究了探测系统分辨时间和计数率对相干态和热态的三阶及四阶光子关联的影响. 在分辨时间为210 ns, 计数率为80 kc/s时, 准确测量得到在零延迟处热态的三阶及四阶光子关联, 相对理论值的统计偏差分别为0.3%和0.8%. 此外还测量得到了不同延迟时间下热态的高阶光子关联的结果. 实验表明综合对各种影响因素的分析可精确测量光场的高阶光子关联, 该方法在量子关联成像及光场特性分析中有着重要的应用.

     

    High-order photon correlations of light fields are important for characterizing the quantum nature. Since Hanbury Brown and Twiss conducted the pioneering experiments in the 1950s, the HBT effect has inspired extensive research on high-order photon correlation in quantum optics, quantum information, and quantum imaging. The Single-photon counting module is one of the most widely used single-photon detectors. Due to its high detection efficiency and low dark counts in the visible and near-infrared region, it is reasonably chosen for basic research on quantum mechanics. Many researches have demonstrated that the maximum value of second-order photon correlation g(2)(τ) at zero delay (τ = 0) can be used to distinguish different light fields. Therefore, the HBT scheme containing two single photon detectors have been widely used in many advanced studies, such as space interference, ghost imaging, single photon detection with high efficiency, etc. However, higher-order photon correlations g(n) (n > 2) can reveal more measurable characteristics of light fields, such as information about the non-Gaussian scattering process, the skewness and kurtosis of photon number distribution, etc. When the extended HBT scheme is used to measure higher-order photon correlations, the experimental conditions including quantum efficiency and background noise greatly affect the photon correlation measurement. The influences of the counting rate and resolution time of the detection system on the measurements are also very important and cannot be ignored. Therefore, the comprehensive considering of various influence factors is necessary for accurately measuring the high-order photon correlations and also a challenge.
    In this paper, we present a method based on double Hanbury Brown-Twiss scheme for the accurate measuring of high-order photon correlations g(n) (n > 2). The system consists of four single photon counting modules and is used to detect and analyze the joint distribution probability of temporal photon correlation. Considering the effects of the background noise and overall efficiency, theoretically, we analyze the correlations of the third- and fourth-order photon with the incident light intensity, squeezing parameter and photon number respectively for thermal state, coherent state, squeezed vacuum state, and Fock state. Meanwhile, experimentally we study the influences of resolution time and counting rate on correlations of the coherent state and thermal state with third- and fourth-order photon. On condition that the resolution time is 210 ns and the counting rate is 80 kc/s, the correlations of third and fourth-order photon with the thermal state at zero time delay are accurately measured, and the relative statistical deviations of the measured vales from the theoretical values are 0.3% and 0.8%, respectively. In addition, the third- and fourth-order photon correlations of the thermal state at different delay times are also observed. It is demonstrated that the high-order photon correlations of light fields are measured accurately by comprehensively analyzing various influencing factors. This technique provides a promising and useful tool to investigate quantum correlated imaging and quantum coherence of light fields.

     

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