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 fabrication of high-quality YBa_(2)Cu_(3)O_(7)−δ(YBCO)nanowires has garnered significant attention in the field of high-temperature superconductivity due to their potential applications in quantum communication,d...The fabrication of high-quality YBa_(2)Cu_(3)O_(7)−δ(YBCO)nanowires has garnered significant attention in the field of high-temperature superconductivity due to their potential applications in quantum communication,deep space exploration,and various other fields.Cl_(2)-assisted reactive ion etching(RIE)stands out as a more effective and efficient method for patterning scalable thin films.However,neither RIE nor high-density RIE has achieved superconducting YBCO nanowires with a width smaller than 3μm.Here,we delve into the factors that limit the line width of Cl_(2)-assisted inductively coupled plasma reactive ion etching(ICP-RIE)processing and the method to elimiate them.Our approach involves utilizing Cl_(2)/Ar as etching gas and incorporating a specialized vacuum heating process after etching.Our experimental results demonstrate the successful realization of 10 nm-thick YBCO nanowires with widths as small as 0.15μm,exhibiting excellent performance in terms of their intrinsic superconducting properties.The mechanism is evidenced by X-ray photoelectron spectroscopy(XPS)analysis in comparison of nanowires with and without heating treatment,in which the residual Cl_(2) on the sidewall of nanowires evaporates and oxidizes Cu^(+)back into Cu^(2+)in an unetched state.展开更多
介绍了2015年上海天文台卫星激光测距系统的常规观测、系统升级改造及科研实验情况。激光观测数据质量已成为国际激光测距台站关注的重要问题。2015年度对上海天文台激光测距系统的接收系统、控制系统和地靶校准系统等进行了改进，使观...介绍了2015年上海天文台卫星激光测距系统的常规观测、系统升级改造及科研实验情况。激光观测数据质量已成为国际激光测距台站关注的重要问题。2015年度对上海天文台激光测距系统的接收系统、控制系统和地靶校准系统等进行了改进，使观测数据质量明显提高，数据稳定性达到国际标准；为提升激光测距能力，开展了效率更高、噪声极低的超导纳米线单光子探测器（superconducting nanowire single photon detector，SNSPDl测距技术研究，在国际上首次采用SNSPD技术成功实现最远20000km卫星测量试验，为实现远距离、小尺寸空间目标的激光测距突破提供了途径：针对白天激光测距望远镜精确指向的关键问题，研究了恒星与大气散射光谱曲线的峰值差异性，并应用短波截止滤光技术，实现了对星等小于3mag的恒星的白天监视，使望远镜白天指向误差均方根优于10”。该研究成果己应用于本站白天卫星激光测距，尤其是高轨卫星激光测距，并起到了重要作用。展开更多
Shortly after their inception, superconducting nanowire single-photon detectors(SNSPDs) became the leading quantum light detection technology. With the capability of detecting single-photons with near-unity efficiency...Shortly after their inception, superconducting nanowire single-photon detectors(SNSPDs) became the leading quantum light detection technology. With the capability of detecting single-photons with near-unity efficiency,high time resolution, low dark count rate, and fast recovery time, SNSPDs outperform conventional single-photon detection techniques. However, detecting lower energy single photons(<0.8 eV) with high efficiency and low timing jitter has remained a challenge. To achieve unity internal efficiency at mid-infrared wavelengths, previous works used amorphous superconducting materials with low energy gaps at the expense of reduced time resolution(close to a nanosecond), and by operating them in complex milli Kelvin(mK) dilution refrigerators. In this work,we provide an alternative approach with SNSPDs fabricated from 5 to 9.5 nm thick NbTiN superconducting films and devices operated in conventional Gifford-McMahon cryocoolers. By optimizing the superconducting film deposition process, film thickness, and nanowire design, our fiber-coupled devices achieved >70% system detection efficiency(SDE) at 2 μm and sub-15 ps timing jitter. Furthermore, detectors from the same batch demonstrated unity internal detection efficiency at 3 μm and 80% internal efficiency at 4 μm, paving the road for an efficient mid-infrared single-photon detection technology with unparalleled time resolution and without mK cooling requirements. We also systematically studied the dark count rates(DCRs) of our detectors coupled to different types of mid-infrared optical fibers and blackbody radiation filters. This offers insight into the trade-off between bandwidth and DCRs for mid-infrared SNSPDs. To conclude, this paper significantly extends the working wavelength range for SNSPDs made from polycrystalline NbTiN to 1.5–4 μm, and we expect quantum optics experiments and applications in the mid-infrared range to benefit from this far-reaching technology.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 present a low-power inductorless wideband differential cryogenic amplifier using a 0.13-μm Si Ge Bi CMOS process for a superconducting nanowire single-photon detector(SNSPD).With a shunt-shunt feedback and capacit...We present a low-power inductorless wideband differential cryogenic amplifier using a 0.13-μm Si Ge Bi CMOS process for a superconducting nanowire single-photon detector(SNSPD).With a shunt-shunt feedback and capacitive coupling structure,theoretical analysis and simulations were undertaken,highlighting the relationship of the amplifier gain with the tunable design parameters of the circuit.In this way,the design and optimization flexibility can be increased,and a required gain can be achieved even without an accurate cryogenic device model.To realize a flat terminal impedance over the frequency of interest,an RC shunt compensation structure was employed,improving the amplifier’s closed-loop stability and suppressing the amplifier overshoot.The S-parameters and transient performance were measured at room temperature(300 K)and cryogenic temperature(4.2 K).With good input and output matching,the measurement results showed that the amplifier achieved a 21-d B gain with a 3-d B bandwidth of 1.13 GHz at 300 K.At 4.2 K,the gain of the amplifier can be tuned from 15 to 24 d B,achieving a 3-d B bandwidth spanning from 120 k Hz to 1.3 GHz and consuming only 3.1 m W.Excluding the chip pads,the amplifier chip core area was only about 0.073 mm^(2).展开更多
By using a high-contrast grating(HCG,high transmittance>90%)to control the phase shift of incident light,we theoretically designed a novel-structured HCG-integrated superconducting nanowire single-photon detector(H...By using a high-contrast grating(HCG,high transmittance>90%)to control the phase shift of incident light,we theoretically designed a novel-structured HCG-integrated superconducting nanowire single-photon detector(HCG-SNSPD)with a high-efficiency and large light-receiving area.Without enlarging the typical single-pixel SNSPD nanowire area(10μm×10μm),the effective detection area is expanded to 115μm,while the absorption efficiency of the nanowire reaches 84.9% at a wavelength of 1550 nm.The effective detection area of HCGSNSPD is increased by 11.5 times compared to that of conventional single-pixel SNSPDs.Moreover,the absorption efficiencies of HCG-SNSPD exceed 70% at wavelengths ranging from 1460 nm to 1650 nm,indicating high-efficiency broadband detection.This study promotes new possibilities for the application of SNSPDs.展开更多
Performances of superconducting nanowire single-photon detectors(SNSPDs) based on low TCmaterials strongly depend on the operating temperatures. We have fabricated infrared-sensitive niobium SNSPDs based on doped niob...Performances of superconducting nanowire single-photon detectors(SNSPDs) based on low TCmaterials strongly depend on the operating temperatures. We have fabricated infrared-sensitive niobium SNSPDs based on doped niobium(Nb*) films and measured them in He-3cryocooler. The critical current approaches to the de-pairing current at 0.3 K. Therefore, with the decrease in temperatures, we have observed a monotonous increase of count rate at the wavelength of 1,521 nm and exponential decrease of dark count rate at all bias currents. The possible origin of dark counts for doped Nb devices is also discussed.展开更多
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 Research and Development Program of China(No.2021YFA0718800)the Natural Science Foundation of Sichuan Province(No.2023NSFSC0993)+1 种基金the National Natural Science Foundation of China(Nos.52021001,U22A20132 and 12074056)Sichuan Science and Technology Program(No.2021JDTD0010).
文摘The fabrication of high-quality YBa_(2)Cu_(3)O_(7)−δ(YBCO)nanowires has garnered significant attention in the field of high-temperature superconductivity due to their potential applications in quantum communication,deep space exploration,and various other fields.Cl_(2)-assisted reactive ion etching(RIE)stands out as a more effective and efficient method for patterning scalable thin films.However,neither RIE nor high-density RIE has achieved superconducting YBCO nanowires with a width smaller than 3μm.Here,we delve into the factors that limit the line width of Cl_(2)-assisted inductively coupled plasma reactive ion etching(ICP-RIE)processing and the method to elimiate them.Our approach involves utilizing Cl_(2)/Ar as etching gas and incorporating a specialized vacuum heating process after etching.Our experimental results demonstrate the successful realization of 10 nm-thick YBCO nanowires with widths as small as 0.15μm,exhibiting excellent performance in terms of their intrinsic superconducting properties.The mechanism is evidenced by X-ray photoelectron spectroscopy(XPS)analysis in comparison of nanowires with and without heating treatment,in which the residual Cl_(2) on the sidewall of nanowires evaporates and oxidizes Cu^(+)back into Cu^(2+)in an unetched state.
文摘介绍了2015年上海天文台卫星激光测距系统的常规观测、系统升级改造及科研实验情况。激光观测数据质量已成为国际激光测距台站关注的重要问题。2015年度对上海天文台激光测距系统的接收系统、控制系统和地靶校准系统等进行了改进，使观测数据质量明显提高，数据稳定性达到国际标准；为提升激光测距能力，开展了效率更高、噪声极低的超导纳米线单光子探测器（superconducting nanowire single photon detector，SNSPDl测距技术研究，在国际上首次采用SNSPD技术成功实现最远20000km卫星测量试验，为实现远距离、小尺寸空间目标的激光测距突破提供了途径：针对白天激光测距望远镜精确指向的关键问题，研究了恒星与大气散射光谱曲线的峰值差异性，并应用短波截止滤光技术，实现了对星等小于3mag的恒星的白天监视，使望远镜白天指向误差均方根优于10”。该研究成果己应用于本站白天卫星激光测距，尤其是高轨卫星激光测距，并起到了重要作用。
基金Vetenskapsradet(2016-06122,Research Environment Grant2013-7152,International Recruitment of Leading Researchers)+4 种基金Knut och Alice Wallenbergs Stiftelse(Quantum Sensors)EU(899580,FET-Open project)European Commission(H2020-MSCA-ITN-642656,Marie-Sklodowska Curie action Phonsi777222,ATTRACT project)China Scholarship Council(201603170247).
文摘Shortly after their inception, superconducting nanowire single-photon detectors(SNSPDs) became the leading quantum light detection technology. With the capability of detecting single-photons with near-unity efficiency,high time resolution, low dark count rate, and fast recovery time, SNSPDs outperform conventional single-photon detection techniques. However, detecting lower energy single photons(<0.8 eV) with high efficiency and low timing jitter has remained a challenge. To achieve unity internal efficiency at mid-infrared wavelengths, previous works used amorphous superconducting materials with low energy gaps at the expense of reduced time resolution(close to a nanosecond), and by operating them in complex milli Kelvin(mK) dilution refrigerators. In this work,we provide an alternative approach with SNSPDs fabricated from 5 to 9.5 nm thick NbTiN superconducting films and devices operated in conventional Gifford-McMahon cryocoolers. By optimizing the superconducting film deposition process, film thickness, and nanowire design, our fiber-coupled devices achieved >70% system detection efficiency(SDE) at 2 μm and sub-15 ps timing jitter. Furthermore, detectors from the same batch demonstrated unity internal detection efficiency at 3 μm and 80% internal efficiency at 4 μm, paving the road for an efficient mid-infrared single-photon detection technology with unparalleled time resolution and without mK cooling requirements. We also systematically studied the dark count rates(DCRs) of our detectors coupled to different types of mid-infrared optical fibers and blackbody radiation filters. This offers insight into the trade-off between bandwidth and DCRs for mid-infrared SNSPDs. To conclude, this paper significantly extends the working wavelength range for SNSPDs made from polycrystalline NbTiN to 1.5–4 μm, and we expect quantum optics experiments and applications in the mid-infrared range to benefit from this far-reaching technology.
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.
基金Project supported by the National Key R&D Program of China(No.2018YFE0205900)the National Science and Technology Major Project of China(No.2018ZX03001008)the Natural Science Foundation of Jiangsu Province,China(No.BK20180368)。
文摘We present a low-power inductorless wideband differential cryogenic amplifier using a 0.13-μm Si Ge Bi CMOS process for a superconducting nanowire single-photon detector(SNSPD).With a shunt-shunt feedback and capacitive coupling structure,theoretical analysis and simulations were undertaken,highlighting the relationship of the amplifier gain with the tunable design parameters of the circuit.In this way,the design and optimization flexibility can be increased,and a required gain can be achieved even without an accurate cryogenic device model.To realize a flat terminal impedance over the frequency of interest,an RC shunt compensation structure was employed,improving the amplifier’s closed-loop stability and suppressing the amplifier overshoot.The S-parameters and transient performance were measured at room temperature(300 K)and cryogenic temperature(4.2 K).With good input and output matching,the measurement results showed that the amplifier achieved a 21-d B gain with a 3-d B bandwidth of 1.13 GHz at 300 K.At 4.2 K,the gain of the amplifier can be tuned from 15 to 24 d B,achieving a 3-d B bandwidth spanning from 120 k Hz to 1.3 GHz and consuming only 3.1 m W.Excluding the chip pads,the amplifier chip core area was only about 0.073 mm^(2).
基金China Scholarship Council(201906755016)Natural Science Foundation of Guangdong Province(2018A0303130176,2019A1515011401)National Natural Science Foundation of China(61801183)。
文摘By using a high-contrast grating(HCG,high transmittance>90%)to control the phase shift of incident light,we theoretically designed a novel-structured HCG-integrated superconducting nanowire single-photon detector(HCG-SNSPD)with a high-efficiency and large light-receiving area.Without enlarging the typical single-pixel SNSPD nanowire area(10μm×10μm),the effective detection area is expanded to 115μm,while the absorption efficiency of the nanowire reaches 84.9% at a wavelength of 1550 nm.The effective detection area of HCGSNSPD is increased by 11.5 times compared to that of conventional single-pixel SNSPDs.Moreover,the absorption efficiencies of HCG-SNSPD exceed 70% at wavelengths ranging from 1460 nm to 1650 nm,indicating high-efficiency broadband detection.This study promotes new possibilities for the application of SNSPDs.
基金financially supported by theNational Basic Research Program of China(2011CBA00107,2011CBA00202)the National Natural Science Foundation of China(11227904 and 61101012)
文摘Performances of superconducting nanowire single-photon detectors(SNSPDs) based on low TCmaterials strongly depend on the operating temperatures. We have fabricated infrared-sensitive niobium SNSPDs based on doped niobium(Nb*) films and measured them in He-3cryocooler. The critical current approaches to the de-pairing current at 0.3 K. Therefore, with the decrease in temperatures, we have observed a monotonous increase of count rate at the wavelength of 1,521 nm and exponential decrease of dark count rate at all bias currents. The possible origin of dark counts for doped Nb devices is also discussed.
