The development of high-fidelity two-qubit quantum gates is essential for digital quantum computing.Here,we propose and realize an all-microwave parametric controlled-Z(CZ)gates by coupling strength modulation in a su...The development of high-fidelity two-qubit quantum gates is essential for digital quantum computing.Here,we propose and realize an all-microwave parametric controlled-Z(CZ)gates by coupling strength modulation in a superconducting Transmon qubit system with tunable couplers.After optimizing the design of the tunable coupler together with the control pulse numerically,we experimentally realized a 100 ns CZ gate with high fidelity of 99.38%±0.34%and the control error being 0.1%.We note that our CZ gates are not affected by pulse distortion and do not need pulse correction,providing a solution for the real-time pulse generation in a dynamic quantum feedback circuit.With the expectation of utilizing our all-microwave control scheme to reduce the number of control lines through frequency multiplexing in the future,our scheme draws a blueprint for the high-integrable quantum hardware design.展开更多
Quantum technology establishes a foundation for secure communication via quantum key distribution （QKD）. In the last two decades, the rapid development of QKD makes a global quantum communication network feasible. I...Quantum technology establishes a foundation for secure communication via quantum key distribution （QKD）. In the last two decades, the rapid development of QKD makes a global quantum communication network feasible. In order to construct this network, it is economical to consider small-sized and low-cost QKD payloads, which can be assembled on satellites with different sizes, such as space stations. Here we report an experimental demonstration of space-to-ground QKD using a small-sized payload, from Tiangong-2 space lab to Nanshan ground station. The 57.9-kg payload integrates a tracking system, a QKD transmitter along with modules for synchronization, and a laser communication transmitter. In the space lab, a 50MHz vacuum＋weak decoy-state optical source is sent through a reflective telescope with an aperture of 200mm. On the ground station, a telescope with an aperture of 1200mm collects the signal photons. A stable and high-transmittance communication channel is set up with a high-precision bidirectional tracking system, a polarization compensation module, and a synchronization system. When the quantum link is successfully established, we obtain a key rate over 100bps with a communication distance up to 719km. Together with our recent development of QKD in daylight, the present demonstration paves the way towards a practical satellite-constellation-based global quantum secure network with small-sized QKD payloads.展开更多
Future optical clock networks will require high-precision optical time-frequency transfer between satellites and ground stations.However,due to atmospheric turbulence,satellite motion and time delay between the satell...Future optical clock networks will require high-precision optical time-frequency transfer between satellites and ground stations.However,due to atmospheric turbulence,satellite motion and time delay between the satellite–ground transmission links will cause spatial and temporal variations,respectively,resulting in the breakdown of the time-of-flight reciprocity on which optical two-way time-frequency transfer is based.Here,we experimentally simulate the atmospheric effects by two-way spatio-temporally separated links between two stationary terminals located 113 km apart and measure the effects for optical two-way time-frequency transfer.Our experiment shows that the effect on the link instability is less than 2.3×10^(−19) at 10,000 s.This indicates that when the link instability of satellite-ground optical time-frequency transfer is on the order of 10^(−19),it is not necessary to consider the atmospheric non-reciprocity effects.展开更多
Single-photon light detection and ranging(lidar)offers single-photon sensitivity and picosecond timing resolution,which is desirable for high-precision three-dimensional(3 D)imaging over long distances.Despite importa...Single-photon light detection and ranging(lidar)offers single-photon sensitivity and picosecond timing resolution,which is desirable for high-precision three-dimensional(3 D)imaging over long distances.Despite important progress,further extending the imaging range presents enormous challenges because only a few echo photons return and are mixed with strong noise.Here,we tackled these challenges by constructing a high-efficiency,low-noise coaxial single-photon lidar system and developing a long-range-tailored computational algorithm that provides high photon efficiency and good noise tolerance.Using this technique,we experimentally demonstrated active single-photon 3 D imaging at a distance of up to 45 km in an urban environment,with a low return-signal level of^1 photon per pixel.Our system is feasible for imaging at a few hundreds of kilometers by refining the setup,and thus represents a step towards low-power and high-resolution lidar over extra-long ranges.展开更多
To ensure a long-term quantum computational advantage,the quantum hardware should be upgraded to withstand the competition of continuously improved classical algorithms and hardwares.Here,we demonstrate a superconduct...To ensure a long-term quantum computational advantage,the quantum hardware should be upgraded to withstand the competition of continuously improved classical algorithms and hardwares.Here,we demonstrate a superconducting quantum computing systems Zuchongzhi 2.1,which has 66 qubits in a two-dimensional array in a tunable coupler architecture.The readout fidelity of Zuchongzhi 2.1 is considerably improved to an average of 97.74%.The more powerful quantum processor enables us to achieve larger-scale random quantum circuit sampling,with a system scale of up to 60 qubits and 24 cycles,and fidelity of FXEB=(3·66±0·345)×10^(-4).The achieved sampling task is about 6 orders of magnitude more difficult than that of Sycamore[Nature 574,505(2019)]in the classic simulation,and 3 orders of magnitude more difficult than the sampling task on Zuchongzhi 2.0[arXiv:2106.14734(2021)].The time consumption of classically simulating random circuit sampling experiment using state-of-the-art classical algorithm and supercomputer is extended to tens of thousands of years(about 4·8×104years),while Zuchongzhi 2.1 only takes about 4.2 h,thereby significantly enhancing the quantum computational advantage.展开更多
We report a quantum key distribution(QKD) system that uses light-emitting-diodes(LEDs) at 1310 nm as optical sources. Compared to the normally used laser diodes(LDs), LEDs are easier to manufacture and integrate, and ...We report a quantum key distribution(QKD) system that uses light-emitting-diodes(LEDs) at 1310 nm as optical sources. Compared to the normally used laser diodes(LDs), LEDs are easier to manufacture and integrate, and thus have the potential to reduce the costs of practical systems. To demonstrate the feasibility of a low-cost, integratable QKD system that aims at meeting the demand of the last-mile secure communication,we utilize LEDs at 1310 nm as the optical sources, while using only passive optical components and only one single photon detector at the receiver’s side. With a repetition rate of 10 MHz, we obtain secure key rates of 10.9 kbps within the experimental time of 1000 s over a fiber length of 1 km.展开更多
基金the USTC Center for Micro-and Nanoscale Research and Fabrication for supporting the sample fabricationQuantum CTek Co.,Ltd.for supporting the fabrication and the maintenance of room-temperature electronics+7 种基金supported by the National Key R&D Program of China(Grant No.2017YFA0304300)the Chinese Academy of Sciencesthe Anhui Initiative in Quantum Information Technologiesthe Technology Committee of Shanghai Municipalitythe National Natural Science Foundation of China(Grants No.11905217 and 11905294)the Natural Science Foundation of Shanghai(Grant No.19ZR1462700)he Key-Area Research and Development Program of Guangdong Province(Grant No.2020B0303030001)the China Postdoctoral Science Foundation。
文摘The development of high-fidelity two-qubit quantum gates is essential for digital quantum computing.Here,we propose and realize an all-microwave parametric controlled-Z(CZ)gates by coupling strength modulation in a superconducting Transmon qubit system with tunable couplers.After optimizing the design of the tunable coupler together with the control pulse numerically,we experimentally realized a 100 ns CZ gate with high fidelity of 99.38%±0.34%and the control error being 0.1%.We note that our CZ gates are not affected by pulse distortion and do not need pulse correction,providing a solution for the real-time pulse generation in a dynamic quantum feedback circuit.With the expectation of utilizing our all-microwave control scheme to reduce the number of control lines through frequency multiplexing in the future,our scheme draws a blueprint for the high-integrable quantum hardware design.
基金Supported by China Manned Space Program,Technology and Engineering Center for Space Utilization Chinese Academy of Sciences,Chinese Academy of Sciencesthe National Natural Science Foundation of China
文摘Quantum technology establishes a foundation for secure communication via quantum key distribution （QKD）. In the last two decades, the rapid development of QKD makes a global quantum communication network feasible. In order to construct this network, it is economical to consider small-sized and low-cost QKD payloads, which can be assembled on satellites with different sizes, such as space stations. Here we report an experimental demonstration of space-to-ground QKD using a small-sized payload, from Tiangong-2 space lab to Nanshan ground station. The 57.9-kg payload integrates a tracking system, a QKD transmitter along with modules for synchronization, and a laser communication transmitter. In the space lab, a 50MHz vacuum＋weak decoy-state optical source is sent through a reflective telescope with an aperture of 200mm. On the ground station, a telescope with an aperture of 1200mm collects the signal photons. A stable and high-transmittance communication channel is set up with a high-precision bidirectional tracking system, a polarization compensation module, and a synchronization system. When the quantum link is successfully established, we obtain a key rate over 100bps with a communication distance up to 719km. Together with our recent development of QKD in daylight, the present demonstration paves the way towards a practical satellite-constellation-based global quantum secure network with small-sized QKD payloads.
基金National Key Research and Development Program of China(2020YFA0309800,2020YFC2200103)Strategic Priority Research Programme of Chinese Academy of Sciences(XDA15020400,XDB35030000)+5 种基金National Natural Science Foundation of China(12274398,61825505,T2125010)Anhui Initiative in Quantum Information Technologies(AHY010100)Key RD Plan of Shandong Province(2020CXGC010105,2021ZDPT01)Shanghai Municipal Science and Technology Major Project(2019SHZDZX01)Innovation Programme for Quantum Science and Technology(2021ZD0300100)Youth Innovation Promotion Association of the Chinese Academy of Sciences(2018492,2021457).
文摘Future optical clock networks will require high-precision optical time-frequency transfer between satellites and ground stations.However,due to atmospheric turbulence,satellite motion and time delay between the satellite–ground transmission links will cause spatial and temporal variations,respectively,resulting in the breakdown of the time-of-flight reciprocity on which optical two-way time-frequency transfer is based.Here,we experimentally simulate the atmospheric effects by two-way spatio-temporally separated links between two stationary terminals located 113 km apart and measure the effects for optical two-way time-frequency transfer.Our experiment shows that the effect on the link instability is less than 2.3×10^(−19) at 10,000 s.This indicates that when the link instability of satellite-ground optical time-frequency transfer is on the order of 10^(−19),it is not necessary to consider the atmospheric non-reciprocity effects.
基金supported by Innovation Program for Quantum Science and Technology (2021ZD0300200)Shanghai Municipal Science and Technology Major Project (2019SHZDZX01)+13 种基金Special funds from Jinan Science and Technology Bureau and Jinan High Tech Zone Management Committeethe Chinese Academy of Sciences (CAS)Anhui Initiative in Quantum Information TechnologiesTechnology Committee of Shanghai MunicipalityNatural Science Foundation of Shandong Province (ZR202209080019)Key-Area Research and Development Program of Guangdong Provice (2020B0303030001)supported in part by the Japanese MEXT Quantum Leap Flagship Program (MEXT Q-LEAP,JPMXS0118069605)the support from the Youth Talent Lifting Project (2020-JCJQ-QT-030)the National Natural Science Foundation of China (12274464,and 11905294)China Postdoctoral Science Foundationthe Open Research Fund from State Key Laboratory of High Performance Computing of China (201901-01)supported by Shanghai Rising-Star Program (23QA1410000)the Youth Innovation Promotion Association of CAS (2022460)the support from THE XPLORER PRIZE。
基金supported by the National Natural Science Foundation of China(91836303 and 11805197)the National Key R&D Program of China+2 种基金the Chinese Academy of Sciencesthe Anhui Initiative in Quantum Information Technologiesthe Science and Technology Commission of Shanghai Municipality(2019SHZDZX01)。
基金National Key Research and Development Program of China(2018YFB0504300)National Natural Science Foundation of China(61771443)+4 种基金Shanghai Municipal Science and Technology Major Project(2019SHZDZX01)Anhui Initiative in Quantum Information TechnologiesShanghai Science and Technology Development Funds(18JC1414700)Fundamental Research Funds for the Central Universities(WK2340000083)Youth Innovation Promotion Association of CAS(2018492)。
文摘Single-photon light detection and ranging(lidar)offers single-photon sensitivity and picosecond timing resolution,which is desirable for high-precision three-dimensional(3 D)imaging over long distances.Despite important progress,further extending the imaging range presents enormous challenges because only a few echo photons return and are mixed with strong noise.Here,we tackled these challenges by constructing a high-efficiency,low-noise coaxial single-photon lidar system and developing a long-range-tailored computational algorithm that provides high photon efficiency and good noise tolerance.Using this technique,we experimentally demonstrated active single-photon 3 D imaging at a distance of up to 45 km in an urban environment,with a low return-signal level of^1 photon per pixel.Our system is feasible for imaging at a few hundreds of kilometers by refining the setup,and thus represents a step towards low-power and high-resolution lidar over extra-long ranges.
基金the National Key R&D Program of China(2017YFA0304300),the Chinese Academy of Sciences,Anhui Initiative in Quantum Information Technologies,Technology Committee of Shanghai Municipality,National Natural Science Foundation of China(11905217,11774326,and 11905294)‘Shang-hai Municipal Science and Technology Major Project(2019SHZDZX01)’Natural Science Foundation of Shanghai(19ZR1462700)‘Key-Area Research and Development Program of Guangdong Province(2020B0303030001)’the Youth Talent Lifting Project(2020-JCJQ-QT-030)。
文摘To ensure a long-term quantum computational advantage,the quantum hardware should be upgraded to withstand the competition of continuously improved classical algorithms and hardwares.Here,we demonstrate a superconducting quantum computing systems Zuchongzhi 2.1,which has 66 qubits in a two-dimensional array in a tunable coupler architecture.The readout fidelity of Zuchongzhi 2.1 is considerably improved to an average of 97.74%.The more powerful quantum processor enables us to achieve larger-scale random quantum circuit sampling,with a system scale of up to 60 qubits and 24 cycles,and fidelity of FXEB=(3·66±0·345)×10^(-4).The achieved sampling task is about 6 orders of magnitude more difficult than that of Sycamore[Nature 574,505(2019)]in the classic simulation,and 3 orders of magnitude more difficult than the sampling task on Zuchongzhi 2.0[arXiv:2106.14734(2021)].The time consumption of classically simulating random circuit sampling experiment using state-of-the-art classical algorithm and supercomputer is extended to tens of thousands of years(about 4·8×104years),while Zuchongzhi 2.1 only takes about 4.2 h,thereby significantly enhancing the quantum computational advantage.
基金National Natural Science Foundation of ChinaChinese Academy of SciencesNational Key R&D Program of China(2017YFA0303900).
文摘We report a quantum key distribution(QKD) system that uses light-emitting-diodes(LEDs) at 1310 nm as optical sources. Compared to the normally used laser diodes(LDs), LEDs are easier to manufacture and integrate, and thus have the potential to reduce the costs of practical systems. To demonstrate the feasibility of a low-cost, integratable QKD system that aims at meeting the demand of the last-mile secure communication,we utilize LEDs at 1310 nm as the optical sources, while using only passive optical components and only one single photon detector at the receiver’s side. With a repetition rate of 10 MHz, we obtain secure key rates of 10.9 kbps within the experimental time of 1000 s over a fiber length of 1 km.
