Fundamental characteristics of the plastic scintillating fiber (PSF) as a detector for electromagnetic radiation (X & γ) are obtained by GEANT4 detector simulation tool package. The detector response to radiation...Fundamental characteristics of the plastic scintillating fiber (PSF) as a detector for electromagnetic radiation (X & γ) are obtained by GEANT4 detector simulation tool package. The detector response to radiation with energy of 10~400 keV is found out. Energy deposition as well as detector efficiency (DE) of the PSF are studied. In order to make linear array of the PSF for imaging purpose, the optimum length of fiber is also estimated.展开更多
It is important to assess image quality, in order to ensure that the imaging system is performing optimally and also identify the weak points in an imaging system. Three parameters mostly leading to image degradation ...It is important to assess image quality, in order to ensure that the imaging system is performing optimally and also identify the weak points in an imaging system. Three parameters mostly leading to image degradation are contrast, spatial resolution and noise. There is always a trade-off between spatial resolution and signal to noise ratio, but in scintillating fiber array detectors spatial resolution is not as important as signal to noise ratio, so we paid more attention to contrast and SNR of the system. By using GEANT4 Monte Carlo detector simulation toolkit, some effec- tive parameters of the linear plastic scintillating fiber (PSF) array as an imaging detector were investigated. Finally we show that it is possible to use this kind of detector to take CT and DR (Digital Radiography) image under certain conditions.展开更多
为了实现In Ga As探测器响应波段向可见增强,在传统的外延材料中加入一层In Ga As腐蚀阻挡层,制备了32×32元平面型In Ga As面阵探测器,采用机械抛光和化学湿法腐蚀相结合的方法,去除了In P衬底.结果表明,探测器的响应波段为0.5~1.7...为了实现In Ga As探测器响应波段向可见增强,在传统的外延材料中加入一层In Ga As腐蚀阻挡层,制备了32×32元平面型In Ga As面阵探测器,采用机械抛光和化学湿法腐蚀相结合的方法,去除了In P衬底.结果表明,探测器的响应波段为0.5~1.7μm,室温下在波长为500 nm处的量子效率约为16%,850 nm处量子效率约为54%,1 550 nm处量子效率约为91%.暗电流大小与衬底减薄之前基本保持一致.理论分析了材料参数对器件量子效率的影响,为进一步优化可见波段探测器的量子效率提供了依据.展开更多
基于超导原理的超导纳米线单光子探测器(superconducting nanowire single photon detector,SNSPD)以其在高量子效率、高计数率、低暗计数和低时间抖动等方面的优势引起广泛的研究。综述了SNSPD的物理模型和研究进展。首先从第一次在实...基于超导原理的超导纳米线单光子探测器(superconducting nanowire single photon detector,SNSPD)以其在高量子效率、高计数率、低暗计数和低时间抖动等方面的优势引起广泛的研究。综述了SNSPD的物理模型和研究进展。首先从第一次在实验上发现超导铅薄膜的电热效应出发讲述了SNSPD的起源。然后从SNSPD进行单光子探测的物理过程出发详细分析了SNSPD的单光子探测机制,并分别根据电热模型和唯象模型对探测机制进行了详细的物理解释。紧接着,详细阐述了量子效率分析模型,指出SNSPD的系统量子效率由本征量子效率、耦合效率和光吸收效率三部分组成。最后,从如何提高入射光子与SNSPD的耦合效率、如何提高光子吸收效率、如何提高SNSPD本征量子效率、研究基于新型材料的SNSPD、如何实现光子数分辨和对光子偏振态不敏感的SNSPD、以及研究SNSPD的噪声机制以减小暗计数和时间抖动等方面详细列举了目前各小组研究SNSPD所取得的最新进展。展开更多
The rapid development of superconducting nanowire single-photon detectors over the past decade has led to numerous advances in quantum information technology. The record for the best system detection efficiency at an ...The rapid development of superconducting nanowire single-photon detectors over the past decade has led to numerous advances in quantum information technology. The record for the best system detection efficiency at an incident photon wavelength of 1550 nm is 93%. This performance was attained from a superconducting nanowire single-photon detector made of amorphous WSi; such detectors are usually operated at sub-Kelvin temperatures. In this study, we first demonstrate superconducting nanowire single-photon detectors made of polycrystalline NbN with system detection efficiency of 90.2% for 1550-nm-wavelength photons at2.1 K, accessible with a compact cryocooler. The system detection efficiency saturated at 92.1% when the temperature was lowered to 1.8 K. We expect the results lighten the practical and high performance superconducting nanowire single-photon detectors to quantum information and other high-end applications.展开更多
We extend a previous model of the author which generalizes Bell local hidden variable models to the case of entangled photon pairs assuming that the standard Bell correlation functions depend on a hidden vacuum index....We extend a previous model of the author which generalizes Bell local hidden variable models to the case of entangled photon pairs assuming that the standard Bell correlation functions depend on a hidden vacuum index. We deduce a generalization of Bell theorem assuming that classical observables are not dichotomic and that photon pair emission and detection is not a stationary stochastic process. We derive a photon imperfect polarization correlation functions due to rotational invariance breaking induced by hidden vacuum spin currents. We implement formally this approach deducing a generalization of C.H.S.H. inequalities which asymptotically converges to the standard one and which might be competitive with standard quantum mechanics predictions. We suggest to test this inequalities conceiving new E.P.R.-Bell like tests with time dependent detector efficiency and photon flux. Finally, we suggest to apply these generalized inequalities to the correlation functions of entangled classical spinning waves realized recently with metamaterials.展开更多
文摘Fundamental characteristics of the plastic scintillating fiber (PSF) as a detector for electromagnetic radiation (X & γ) are obtained by GEANT4 detector simulation tool package. The detector response to radiation with energy of 10~400 keV is found out. Energy deposition as well as detector efficiency (DE) of the PSF are studied. In order to make linear array of the PSF for imaging purpose, the optimum length of fiber is also estimated.
文摘It is important to assess image quality, in order to ensure that the imaging system is performing optimally and also identify the weak points in an imaging system. Three parameters mostly leading to image degradation are contrast, spatial resolution and noise. There is always a trade-off between spatial resolution and signal to noise ratio, but in scintillating fiber array detectors spatial resolution is not as important as signal to noise ratio, so we paid more attention to contrast and SNR of the system. By using GEANT4 Monte Carlo detector simulation toolkit, some effec- tive parameters of the linear plastic scintillating fiber (PSF) array as an imaging detector were investigated. Finally we show that it is possible to use this kind of detector to take CT and DR (Digital Radiography) image under certain conditions.
文摘为了实现In Ga As探测器响应波段向可见增强,在传统的外延材料中加入一层In Ga As腐蚀阻挡层,制备了32×32元平面型In Ga As面阵探测器,采用机械抛光和化学湿法腐蚀相结合的方法,去除了In P衬底.结果表明,探测器的响应波段为0.5~1.7μm,室温下在波长为500 nm处的量子效率约为16%,850 nm处量子效率约为54%,1 550 nm处量子效率约为91%.暗电流大小与衬底减薄之前基本保持一致.理论分析了材料参数对器件量子效率的影响,为进一步优化可见波段探测器的量子效率提供了依据.
文摘基于超导原理的超导纳米线单光子探测器(superconducting nanowire single photon detector,SNSPD)以其在高量子效率、高计数率、低暗计数和低时间抖动等方面的优势引起广泛的研究。综述了SNSPD的物理模型和研究进展。首先从第一次在实验上发现超导铅薄膜的电热效应出发讲述了SNSPD的起源。然后从SNSPD进行单光子探测的物理过程出发详细分析了SNSPD的单光子探测机制,并分别根据电热模型和唯象模型对探测机制进行了详细的物理解释。紧接着,详细阐述了量子效率分析模型,指出SNSPD的系统量子效率由本征量子效率、耦合效率和光吸收效率三部分组成。最后,从如何提高入射光子与SNSPD的耦合效率、如何提高光子吸收效率、如何提高SNSPD本征量子效率、研究基于新型材料的SNSPD、如何实现光子数分辨和对光子偏振态不敏感的SNSPD、以及研究SNSPD的噪声机制以减小暗计数和时间抖动等方面详细列举了目前各小组研究SNSPD所取得的最新进展。
基金supported by the National Key R&D Program of China(Grant No.2017YFA0304000)Strategic Priority Research Program(B)of the Chinese Academy of Sciences(Grant No.XDB04010200)+1 种基金the National Natural Science Foundation of China(Grant Nos.91121022,61401441,and61401443)the Science and Technology Commission of Shanghai Municipality(Grant No.16JC1400402)
文摘The rapid development of superconducting nanowire single-photon detectors over the past decade has led to numerous advances in quantum information technology. The record for the best system detection efficiency at an incident photon wavelength of 1550 nm is 93%. This performance was attained from a superconducting nanowire single-photon detector made of amorphous WSi; such detectors are usually operated at sub-Kelvin temperatures. In this study, we first demonstrate superconducting nanowire single-photon detectors made of polycrystalline NbN with system detection efficiency of 90.2% for 1550-nm-wavelength photons at2.1 K, accessible with a compact cryocooler. The system detection efficiency saturated at 92.1% when the temperature was lowered to 1.8 K. We expect the results lighten the practical and high performance superconducting nanowire single-photon detectors to quantum information and other high-end applications.
文摘We extend a previous model of the author which generalizes Bell local hidden variable models to the case of entangled photon pairs assuming that the standard Bell correlation functions depend on a hidden vacuum index. We deduce a generalization of Bell theorem assuming that classical observables are not dichotomic and that photon pair emission and detection is not a stationary stochastic process. We derive a photon imperfect polarization correlation functions due to rotational invariance breaking induced by hidden vacuum spin currents. We implement formally this approach deducing a generalization of C.H.S.H. inequalities which asymptotically converges to the standard one and which might be competitive with standard quantum mechanics predictions. We suggest to test this inequalities conceiving new E.P.R.-Bell like tests with time dependent detector efficiency and photon flux. Finally, we suggest to apply these generalized inequalities to the correlation functions of entangled classical spinning waves realized recently with metamaterials.
