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
Efficient and precise photon-number-resolving detectors are essential for optical quantum information science.Despite this,very few detectors have been able to distinguish photon numbers with both high fidelity and a ...Efficient and precise photon-number-resolving detectors are essential for optical quantum information science.Despite this,very few detectors have been able to distinguish photon numbers with both high fidelity and a large dynamic range,all while maintaining high speed and high timing precision.Superconducting nanostrip-based detectors excel at counting single photons efficiently and rapidly,but face challenges in balancing dynamic range and fidelity.Here,we have pioneered the demonstration of 10 true photon-number resolution using a superconducting microstrip detector,with readout fidelity reaching an impressive 98%and 90%for 4-photon and 6-photon events,respectively.Furthermore,our proposed dual-channel timing setup drastically reduces the amount of data acquisition by 3 orders of magnitude,allowing for real-time photon-number readout.We then demonstrate the utility of our scheme by implementing a quantum random-number generator based on sampling the parity of a coherent state,which guarantees inherent unbiasedness,robustness against experimental imperfections and environmental noise,as well as invulnerability to eavesdropping.Our solution boasts high fidelity,a large dynamic range,and real-time characterization for photon-number resolution and simplicity with respect to device structure,fabrication,and readout,which may provide a promising avenue towards optical quantum information science.展开更多
The optical coupling of superconducting nanowire single-photon detectors （SNSPDs） has always been restricted to a single-mode fiber for a limited detection area. In this study, for enhancing photon coupling, a dual-...The optical coupling of superconducting nanowire single-photon detectors （SNSPDs） has always been restricted to a single-mode fiber for a limited detection area. In this study, for enhancing photon coupling, a dual-lens system operating at 2.2 K was used to compress the beam size on the basis of the Gaussian beam theory and geometric approximation. A magnification of approximately 0.3 was obtained, and a focused spot with diameter of approximately 10 ~m was measured from a multimode fiber. Assisted with the compressed beam, a system efficiency of 55 % （1550 nm） was achieved for a SNSPD with a detection area of 10 μm × 10 μm and 62.5 pm multimode fiber coupling. At the same time, a high speed of 106 MHz was measured with the proposed system. The realization of a highly compressed optical beam reduced the optical coupling requirement and helped maintain a high speed for the SNSPD.展开更多
We report a superconducting nanowire single‐photon detector(SNSPD)array aiming for a near‐infrared 1550‐nm wavelength that consists of 32×32 nanowire pixels and an area of 0.96 mm×0.96 mm.Unlike most repo...We report a superconducting nanowire single‐photon detector(SNSPD)array aiming for a near‐infrared 1550‐nm wavelength that consists of 32×32 nanowire pixels and an area of 0.96 mm×0.96 mm.Unlike most reported large‐scale SNSPD arrays with amorphous films,NbN superconducting nanowires are employed in our array,which allows the detector operation at 2.3 K provided by a compact two‐stage Gifford–McMahon cryocooler.Thermally coupled row–column multiplexing is employed in our arrays to avoid current redistribution and loss of electrical signal occurring in the electrically coupled row–column architecture.The fabricated detector array shows a pixel yield of 94%and maximal intrinsic efficiencies of 77%and 96%at 1550 nm and 405 nm,respectively.The timing jitter and the thermal coupling probability are also investigated.展开更多
The dark count is one of the key physical issues for superconducting nanowire single-photon detectors(SNSPDs)that limits various applications for optical quantum information and classical optics.When the bias current ...The dark count is one of the key physical issues for superconducting nanowire single-photon detectors(SNSPDs)that limits various applications for optical quantum information and classical optics.When the bias current approaches the switching current of SNSPDs,the dark count is actually dominated by the intrinsic dark counts(iDCs).However,the origin of iDCs and its relation to constrictions remains unclear for practical SNSPDs.We herein systematically characterize the iDCs of the SNSPDs with and without artificial geometric constrictions by applying the differential readout method.For these devices with constrictions,we have observed distinct Gaussian distributions in the temporal distribution of iDCs,in which the time difference between the distributions is consistent with the geometric distance between constrictions,and the rates of iDCs produced by each constriction are in good agreement with constrictions'widths.With respect to practical SNSPDs,surprisingly,we also observe several Gaussian distributions in the temporal domain and it shows no significant dependence on the devices’sizes,demonstrating that the iDCs of SNSPDs are mainly dominated by a few specific constrictions.展开更多
Increasing the detection efficiency （DE） is a hot issue in the development of the superconducting nanowire single photon detector （SNSPD）. In this work, a cavity-integrated structure coupled to the SNSPD is used t...Increasing the detection efficiency （DE） is a hot issue in the development of the superconducting nanowire single photon detector （SNSPD）. In this work, a cavity-integrated structure coupled to the SNSPD is used to enhance the light absorption of nanowire. Ultra-thin Nb films are successfully prepared by magnetron sputtering, which are used to fabricate Nb/Al SNSPD with the curve of lOOnm and the square area of 4 × 4μm2 by sputtering and the lift-off method. To characterize the optical and electrical performance of the cavity-integrated SNSPD, a reliable cryogenic research system is built up based on a He3 system. To satisfy the need of light coupling, a packaging structure with collimator is conducted. Both DE and the dark count rates increase with lb. It is also found that the DE of SNSPD with cavities can be up to 0.17% at the temperature of 0.7K under the infrared light of 1550nm, which is obviously higher than that of the SNSPD directly fabricated upon silicon without any cavity structure.展开更多
The performance of single-photon detectors can be enhanced by using nano-antenna. The characteristics of the superconducting nano-wire single-photon detector with cavity plus anti-reflect coating and specially designe...The performance of single-photon detectors can be enhanced by using nano-antenna. The characteristics of the superconducting nano-wire single-photon detector with cavity plus anti-reflect coating and specially designed nano~ antenna is analysed. The photon collection efficiency of the detector is enhanced without damaging the detector＇s speed, thus getting rid of the dilemma of speed and efficiency. The characteristics of nano-antenna are discussed, such as the position and the effect of the active area, and the best result is given. The photon collection efficiency is increased by 92 times compared with that of existing detectors.展开更多
Superconducting nanowire single-photon detectors （SNSPDs） with a composite optical structure composed of phase-grating and optical cavity structures are designed to enhance both the system detection efficiency and t...Superconducting nanowire single-photon detectors （SNSPDs） with a composite optical structure composed of phase-grating and optical cavity structures are designed to enhance both the system detection efficiency and the response bandwidth. Numerical simulation by the finite-difference time-domain method shows that the photon absorption capacity of SNSPDs with a composite optical structure can be enhanced significantly by adjusting the parameters of the phase-grating and optical cavity structures at multiple frequency bands. The absorption capacity of the superconducting nanowires reaches 70%, 72%, 60.73%, 61.7%, 41.2%, and 46.5% at wavelengths of 684, 850, 732, 924, 1256, and 1426nm, respectively. The use of a composite optical structure reduces the total filling factor of superconducting nanowires to only 0.25, decreases the kinetic inductance of SNSPDs, and improves the count rates.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
Single photon detection is one of the key technologies for quantum key distribution in quantum communication. As a novel single photon detection technology, superconducting nanowire single photon detector (SNSPD) surp...Single photon detection is one of the key technologies for quantum key distribution in quantum communication. As a novel single photon detection technology, superconducting nanowire single photon detector (SNSPD) surpasses conventional semiconducting single photon detectors with high count rate and low dark count rate. In this article, we introduce SNSPD fabricated from NbN ultrathin superconducting film and lab-based SNSPD system. The characteristics of single photon response pulse of SNSPD are analyzed in detail. Also discussed is the relationship between waveform of single photon response and system bandwidth. Circuit model is made to analyze the performance of SNSPD. The simulation result agrees well with the experimental data. Those results are valuable for understanding the mechanism of SNSPD and building future SNSPD system for quantum communication.展开更多
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supported by the National Natural Science Foundation of China(Grant Nos.62301541,61971408,61827823,and 12033007)support from Shanghai Sailing Program(Grant No.23YF1456200)
文摘Efficient and precise photon-number-resolving detectors are essential for optical quantum information science.Despite this,very few detectors have been able to distinguish photon numbers with both high fidelity and a large dynamic range,all while maintaining high speed and high timing precision.Superconducting nanostrip-based detectors excel at counting single photons efficiently and rapidly,but face challenges in balancing dynamic range and fidelity.Here,we have pioneered the demonstration of 10 true photon-number resolution using a superconducting microstrip detector,with readout fidelity reaching an impressive 98%and 90%for 4-photon and 6-photon events,respectively.Furthermore,our proposed dual-channel timing setup drastically reduces the amount of data acquisition by 3 orders of magnitude,allowing for real-time photon-number readout.We then demonstrate the utility of our scheme by implementing a quantum random-number generator based on sampling the parity of a coherent state,which guarantees inherent unbiasedness,robustness against experimental imperfections and environmental noise,as well as invulnerability to eavesdropping.Our solution boasts high fidelity,a large dynamic range,and real-time characterization for photon-number resolution and simplicity with respect to device structure,fabrication,and readout,which may provide a promising avenue towards optical quantum information science.
基金supported by the National Basic Research Program of China(2011CBA02)the National Natural Science Foundation of China(61471189,11227904 and 61101012)
文摘The optical coupling of superconducting nanowire single-photon detectors （SNSPDs） has always been restricted to a single-mode fiber for a limited detection area. In this study, for enhancing photon coupling, a dual-lens system operating at 2.2 K was used to compress the beam size on the basis of the Gaussian beam theory and geometric approximation. A magnification of approximately 0.3 was obtained, and a focused spot with diameter of approximately 10 ~m was measured from a multimode fiber. Assisted with the compressed beam, a system efficiency of 55 % （1550 nm） was achieved for a SNSPD with a detection area of 10 μm × 10 μm and 62.5 pm multimode fiber coupling. At the same time, a high speed of 106 MHz was measured with the proposed system. The realization of a highly compressed optical beam reduced the optical coupling requirement and helped maintain a high speed for the SNSPD.
基金the National Natural Science Foundation of China(61971408,61827823,12033007)Shanghai Municipal Science and Technology Major Project(2019SHZDZX01)+2 种基金Shanghai Rising‐Star Program(20QA1410900)Youth Innovation Promotion Association of the Chinese Academy of Sciences(2020241)for their financial supportShanghai Sailing Program(Grants No.21YF1455700).
文摘We report a superconducting nanowire single‐photon detector(SNSPD)array aiming for a near‐infrared 1550‐nm wavelength that consists of 32×32 nanowire pixels and an area of 0.96 mm×0.96 mm.Unlike most reported large‐scale SNSPD arrays with amorphous films,NbN superconducting nanowires are employed in our array,which allows the detector operation at 2.3 K provided by a compact two‐stage Gifford–McMahon cryocooler.Thermally coupled row–column multiplexing is employed in our arrays to avoid current redistribution and loss of electrical signal occurring in the electrically coupled row–column architecture.The fabricated detector array shows a pixel yield of 94%and maximal intrinsic efficiencies of 77%and 96%at 1550 nm and 405 nm,respectively.The timing jitter and the thermal coupling probability are also investigated.
基金the National Key R&D Program of China(2017YFA0304000)National Natural Science Foundation of China(Grant Nos.61971408 and 61827823)+2 种基金Shanghai Municipal Science and Technology Major Project(2019SHZDZX01)Shanghai Rising-Star Program(20QA1410900)the Youth Innovation Promotion Association of Chinese Academy of Sciences(2020241,2021230).
文摘The dark count is one of the key physical issues for superconducting nanowire single-photon detectors(SNSPDs)that limits various applications for optical quantum information and classical optics.When the bias current approaches the switching current of SNSPDs,the dark count is actually dominated by the intrinsic dark counts(iDCs).However,the origin of iDCs and its relation to constrictions remains unclear for practical SNSPDs.We herein systematically characterize the iDCs of the SNSPDs with and without artificial geometric constrictions by applying the differential readout method.For these devices with constrictions,we have observed distinct Gaussian distributions in the temporal distribution of iDCs,in which the time difference between the distributions is consistent with the geometric distance between constrictions,and the rates of iDCs produced by each constriction are in good agreement with constrictions'widths.With respect to practical SNSPDs,surprisingly,we also observe several Gaussian distributions in the temporal domain and it shows no significant dependence on the devices’sizes,demonstrating that the iDCs of SNSPDs are mainly dominated by a few specific constrictions.
基金Supported by the National Basic Research Program of China under Grant No 2011CBA00304the National Natural Science Foundation of China under Grant Nos 60836001 and 61174084the Tsinghua University Initiative Scientific Research Program under Grant No 20131089314
文摘Increasing the detection efficiency （DE） is a hot issue in the development of the superconducting nanowire single photon detector （SNSPD）. In this work, a cavity-integrated structure coupled to the SNSPD is used to enhance the light absorption of nanowire. Ultra-thin Nb films are successfully prepared by magnetron sputtering, which are used to fabricate Nb/Al SNSPD with the curve of lOOnm and the square area of 4 × 4μm2 by sputtering and the lift-off method. To characterize the optical and electrical performance of the cavity-integrated SNSPD, a reliable cryogenic research system is built up based on a He3 system. To satisfy the need of light coupling, a packaging structure with collimator is conducted. Both DE and the dark count rates increase with lb. It is also found that the DE of SNSPD with cavities can be up to 0.17% at the temperature of 0.7K under the infrared light of 1550nm, which is obviously higher than that of the SNSPD directly fabricated upon silicon without any cavity structure.
基金Project supported by the National Basic Research Program of China(Grant No.2010CB923202)
文摘The performance of single-photon detectors can be enhanced by using nano-antenna. The characteristics of the superconducting nano-wire single-photon detector with cavity plus anti-reflect coating and specially designed nano~ antenna is analysed. The photon collection efficiency of the detector is enhanced without damaging the detector＇s speed, thus getting rid of the dilemma of speed and efficiency. The characteristics of nano-antenna are discussed, such as the position and the effect of the active area, and the best result is given. The photon collection efficiency is increased by 92 times compared with that of existing detectors.
基金Supported by the National Basic Research Program of China under Grant Nos 2011CBA00100 and 2011CBA00200the National Natural Science Foundation of China under Grant Nos 11227904 and 61101012+1 种基金the National High-Technology ResearchDevelopment Program of China under Grant No 2011AA010204the Jiangsu Key Laboratory of Advanced Techniques for Manipulating Electromagnetic Waves
文摘Superconducting nanowire single-photon detectors （SNSPDs） with a composite optical structure composed of phase-grating and optical cavity structures are designed to enhance both the system detection efficiency and the response bandwidth. Numerical simulation by the finite-difference time-domain method shows that the photon absorption capacity of SNSPDs with a composite optical structure can be enhanced significantly by adjusting the parameters of the phase-grating and optical cavity structures at multiple frequency bands. The absorption capacity of the superconducting nanowires reaches 70%, 72%, 60.73%, 61.7%, 41.2%, and 46.5% at wavelengths of 684, 850, 732, 924, 1256, and 1426nm, respectively. The use of a composite optical structure reduces the total filling factor of superconducting nanowires to only 0.25, decreases the kinetic inductance of SNSPDs, and improves the count rates.
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supported by the National Natural Science Foundation of China (Grant No. 60801046)National Basic re-search Pogram of China(Grant No.2009CB929602)Science and Technology Commission of Shanghai Municipality (Grant Nos. 08dz1400702 & 08PJ1411200)
文摘Single photon detection is one of the key technologies for quantum key distribution in quantum communication. As a novel single photon detection technology, superconducting nanowire single photon detector (SNSPD) surpasses conventional semiconducting single photon detectors with high count rate and low dark count rate. In this article, we introduce SNSPD fabricated from NbN ultrathin superconducting film and lab-based SNSPD system. The characteristics of single photon response pulse of SNSPD are analyzed in detail. Also discussed is the relationship between waveform of single photon response and system bandwidth. Circuit model is made to analyze the performance of SNSPD. The simulation result agrees well with the experimental data. Those results are valuable for understanding the mechanism of SNSPD and building future SNSPD system for quantum communication.
