Prudkovskii Pavel, Leontyev Andrey, Kuznetsov Kirill, Kitaeva Galiya
Faculty of Physics, Lomonosov Moscow State University, 119991 Moscow, Russia.
Sensors (Basel). 2021 Jul 21;21(15):4964. doi: 10.3390/s21154964.
Statistical distributions of the analog readings of an antenna-coupled THz superconducting bolometer were measured and analyzed under a special type of irradiation by low-energy fluxes of THz photons with Poisson photon statistics and controllable mean photon numbers. The photons were generated via low-gain parametric down-conversion in pulse-pumped Mg:LiNbO crystal placed to a cooled cryostat together with the bolometer NbN film. Results of theoretical approximation of experimental histograms reveal the discrete nature of THz detection by superconducting bolometers and open a way for studying their quantum characteristics. It is shown that bolometer readings per pulse consist of discrete counts ("single charges"), with the mean number linearly dependent on the number of input photons. Contributions of single counts to a total analog reading are statistically distributed according to the normal law, with average values slightly depending on the number of counts in each reading. A general formula is proposed to describe the relationship between continuous statistical distribution of the bolometer readings and discrete quantum statistics of the incident photons.
在具有泊松光子统计特性且平均光子数可控的太赫兹光子低能通量的特殊类型辐照下，测量并分析了天线耦合太赫兹超导测辐射热计模拟读数的统计分布。光子通过脉冲泵浦的Mg:LiNbO晶体中的低增益参量下转换产生，该晶体与测辐射热计NbN薄膜一起放置在冷却低温恒温器中。实验直方图的理论近似结果揭示了超导测辐射热计太赫兹探测的离散性质，并为研究其量子特性开辟了道路。结果表明，每个脉冲的测辐射热计读数由离散计数（“单电荷”）组成，平均数量与输入光子数呈线性相关。单次计数对总模拟读数的贡献根据正态分布进行统计分布，平均值略有依赖于每次读数中的计数数量。提出了一个通用公式来描述测辐射热计读数的连续统计分布与入射光子的离散量子统计之间的关系。
