Weak measurement amplification,which is considered as a very promising scheme in precision measurement,has been applied to various small physical quantities estimations.Since many physical quantities can be converted ...Weak measurement amplification,which is considered as a very promising scheme in precision measurement,has been applied to various small physical quantities estimations.Since many physical quantities can be converted into phase signals,it is interesting and important to consider measuring small longitudinal phase shifts by using weak measurement.Here,we propose and experimentally demonstrate a novel weak measurement amplification-based small longitudinal phase estimation,which is suitable for polarization interferometry.We realize one order of magnitude amplification measurement of a small phase signal directly introduced by a liquid crystal variable retarder and show that it is robust to the imperfection of interference.Besides,we analyze the effect of magnification error which is never considered in the previous works,and find the constraint on the magnification.Our results may find important applications in high-precision measurements,e.g.,gravitational wave detection.展开更多
Controlled quantum teleportation(CQT), which is regarded as the prelude and backbone for a genuine quantum internet, reveals the cooperation, supervision, and control relationship among the sender, receiver, and contr...Controlled quantum teleportation(CQT), which is regarded as the prelude and backbone for a genuine quantum internet, reveals the cooperation, supervision, and control relationship among the sender, receiver, and controller in the quantum network within the simplest unit. Compared with low-dimensional counterparts, high-dimensional CQT can exhibit larger information transmission capacity and higher superiority of the controller's authority. In this article, we report a proof-of-principle experimental realization of three-dimensional(3D) CQT with a fidelity of 97.4% ± 0.2%. To reduce the complexity of the circuit, we simulate a standard 4-qutrit CQT protocol in a 9×9-dimensional two-photon system with high-quality operations. The corresponding control powers are 48.1% ± 0.2% for teleporting a qutrit and 52.8% ± 0.3% for teleporting a qubit in the experiment, which are both higher than the theoretical value of control power in 2-dimensional CQT protocol(33%). The results fully demonstrate the advantages of high-dimensional multi-partite entangled networks and provide new avenues for constructing complex quantum networks.展开更多
The quantum Toffoli gate is one of the most important three-qubit gates,but it is challenging to construct a chip according to the complicated traditional circuit.Using the optimized 3D configuration with an overpass ...The quantum Toffoli gate is one of the most important three-qubit gates,but it is challenging to construct a chip according to the complicated traditional circuit.Using the optimized 3D configuration with an overpass waveguide to reduce the circuit complexity,we successfully fabricate an on-chip path encoded photonic quantum Toffoli gate enabled by the 3D capability of the femtosecond laser direct writing(FLDW)for the first time to our knowledge,whose truth-table fidelity is higher than 85.5%.Furthermore,a path encoded four-qubit controlled-controlled-controlled NOT gate is written to confirm the scalability of this resource-saving technique.This work paves the way for the FLDW of more complex and powerful photonic quantum computation chips.展开更多
Entanglement purification is to distill high-quality entangled states from low-quality entangled states.It is a key step in quantum repeaters,determines the efficiency and communication rates of quantum communication ...Entanglement purification is to distill high-quality entangled states from low-quality entangled states.It is a key step in quantum repeaters,determines the efficiency and communication rates of quantum communication protocols,and is hence of central importance in long-distance communications and quantum networks.In this work,we report the first experimental demonstration of deterministic entanglement purification using polarization and spatial mode hyperentanglement.After purification,the fidelity of polarization entanglement arises from 0.268±0.002 to 0.989±0.001.Assisted with robust spatial mode entanglement,the total purification efficiency can be estimated as 10^(9) times that of the entanglement purification protocols using two copies of entangled states when one uses the spontaneous parametric down-conversion sources.Our work may have the potential to be implemented as a part of full repeater protocols.展开更多
Quantum nonlocality and quantum contextuality are the most curious properties that change our understanding of nature, and were observed independently in recent decades. One important question is whether both properti...Quantum nonlocality and quantum contextuality are the most curious properties that change our understanding of nature, and were observed independently in recent decades. One important question is whether both properties can be observed simultaneously. In this paper, we show that in a qutrit-qutrit system we can observe quantum nonlocality and quantum contextuality at the same time. From the perspective of quantum information, our experiment proves in principle that the two resources, quantum nonlocality and quantum contextuality, can be utilized simultaneously.展开更多
Nonlocal correlation plays an important role in device independent quantum information processing.The stan-dard Bell nonlocality has been well studied with single local hidden variables,however the nonlocal correlatio...Nonlocal correlation plays an important role in device independent quantum information processing.The stan-dard Bell nonlocality has been well studied with single local hidden variables,however the nonlocal correlations in general networks with several independent quantum sources and distant observers have been far less explored.Here,by using three independent entangled photon sources and recently constructed nonlinear Bell inequalities,we experimentally test the nonlocal correlations in the network scenario with different topologies.The violation of the inequalities can be obtained simply with separate measurements,which is much more favourable from the practical point of view.Our experiment results show a violation as 0.7779±0.0093 for the star network,and 0.7303±0.0024 for the chain network.Furthermore,we demonstrate that more measurement settings for each observer can bound more information against an eavesdropper.展开更多
Incompatible measurements are of fundamental importance to re-vealing the peculiar features of quantum theory,and are also use-ful resources in various quantum information tasks.In this work,we investigate the quantum...Incompatible measurements are of fundamental importance to re-vealing the peculiar features of quantum theory,and are also use-ful resources in various quantum information tasks.In this work,we investigate the quantum incompatibility of mutually unbiased bases(MUBs)within the operational framework of quantum resource the-ory,and report an experimental validation via the task of state dis-crimination.In particular,we construct an experimentally friendly witness to detect incompatible MUBs,based on the probability of cor-rectly discriminating quantum states.Furthermore,we prove that the noise robustness of MUBs can be retrieved from violating the above witness.Finally,we experimentally test the incompatibility of MUBs of dimensionality ranging from 2 to 4,and demonstrate that it is more robust to noise,as either the dimensionality of measurements or the number of MUBs increases.Our results may aid the exploration of the essential roles of incompatible measurements in both theoretical and practical applications in quantum information.展开更多
基金Project supported by the National Natural Science Foundation of China (Grant Nos. 92065113, 11904357, 62075208, and 12174367)the Innovation Programme for Quantum Science and Technology (Grant No. 2021ZD0301604)+1 种基金the National Key Research and Development Program of China (Grant No. 2021YFE0113100)supported by Beijing Academy of Quantum Information Sciences
文摘Weak measurement amplification,which is considered as a very promising scheme in precision measurement,has been applied to various small physical quantities estimations.Since many physical quantities can be converted into phase signals,it is interesting and important to consider measuring small longitudinal phase shifts by using weak measurement.Here,we propose and experimentally demonstrate a novel weak measurement amplification-based small longitudinal phase estimation,which is suitable for polarization interferometry.We realize one order of magnitude amplification measurement of a small phase signal directly introduced by a liquid crystal variable retarder and show that it is robust to the imperfection of interference.Besides,we analyze the effect of magnification error which is never considered in the previous works,and find the constraint on the magnification.Our results may find important applications in high-precision measurements,e.g.,gravitational wave detection.
基金supported by the Innovation Program for Quantum Science and Technology (2021ZD0301400)the National Natural Science Foundation of China (61725504, 11774335, 11821404, U19A2075)+1 种基金the Fundamental Research Funds for the Central Universities ( WK2030380017, WK2030000056)Anhui Initiative in Quantum Information Technologies (AHY020100, AHY060300)
基金supported by the National Key Research and Development Program of China (Grant No. 2021YFE0113100)the National Natural Science Foundation of China (Grant Nos. 11904357, 12174367, 12204458,12374338, 62071064, and 62322513)+6 种基金the Innovation Program for Quantum Science and Technology (Grant No. 2021ZD0301200)the Fundamental Research Funds for the Central UniversitiesUSTC Tang ScholarshipScience and Technological Fund of Anhui Province for Outstanding Youth(Grant No. 2008085J02)the China Postdoctoral Science Foundation (Grant No. 2021M700138)the China Postdoctoral for Innovative Talents (Grant No. BX2021289)the Shanghai Municipal Science and Technology Fundamental Project (Grant No. 21JC1405400)。
文摘Controlled quantum teleportation(CQT), which is regarded as the prelude and backbone for a genuine quantum internet, reveals the cooperation, supervision, and control relationship among the sender, receiver, and controller in the quantum network within the simplest unit. Compared with low-dimensional counterparts, high-dimensional CQT can exhibit larger information transmission capacity and higher superiority of the controller's authority. In this article, we report a proof-of-principle experimental realization of three-dimensional(3D) CQT with a fidelity of 97.4% ± 0.2%. To reduce the complexity of the circuit, we simulate a standard 4-qutrit CQT protocol in a 9×9-dimensional two-photon system with high-quality operations. The corresponding control powers are 48.1% ± 0.2% for teleporting a qutrit and 52.8% ± 0.3% for teleporting a qubit in the experiment, which are both higher than the theoretical value of control power in 2-dimensional CQT protocol(33%). The results fully demonstrate the advantages of high-dimensional multi-partite entangled networks and provide new avenues for constructing complex quantum networks.
基金National Key Research and Development Program of China(2018YFB1107205,2016YFA0301302)National Natural Science Foundation of China(12134001,61590933,61590932,11527901,11774333,62061160487)+2 种基金Joint Fund for Equipment Pre-research Space Science and Technology(6141B06140601)Strategic Priority Research Program of the Chinese Academy of Sciences(CAS)(XDB24030601)Fundamental Research Funds for the Central Universities。
文摘The quantum Toffoli gate is one of the most important three-qubit gates,but it is challenging to construct a chip according to the complicated traditional circuit.Using the optimized 3D configuration with an overpass waveguide to reduce the circuit complexity,we successfully fabricate an on-chip path encoded photonic quantum Toffoli gate enabled by the 3D capability of the femtosecond laser direct writing(FLDW)for the first time to our knowledge,whose truth-table fidelity is higher than 85.5%.Furthermore,a path encoded four-qubit controlled-controlled-controlled NOT gate is written to confirm the scalability of this resource-saving technique.This work paves the way for the FLDW of more complex and powerful photonic quantum computation chips.
基金supported by the National Key Research and Development Program of China(2021YFE0113100 and 2017YFA0304100)the National Natural Science Foundation of China(11774335,11734015,11874345,11821404,11904357,11974189,12174367,and 12175106)+4 种基金the Key Research Program of Frontier Sciences,Chinese Academy of Sciences(CAS,QYZDYSSW-SLH003)Science Foundation of the CAS(ZDRW-XH-2019-1)the Fundamental Research Funds for the Central UniversitiesUSTC Tang ScholarshipScience and Technological Fund of Anhui Province for Outstanding Youth(2008085J02)。
文摘Entanglement purification is to distill high-quality entangled states from low-quality entangled states.It is a key step in quantum repeaters,determines the efficiency and communication rates of quantum communication protocols,and is hence of central importance in long-distance communications and quantum networks.In this work,we report the first experimental demonstration of deterministic entanglement purification using polarization and spatial mode hyperentanglement.After purification,the fidelity of polarization entanglement arises from 0.268±0.002 to 0.989±0.001.Assisted with robust spatial mode entanglement,the total purification efficiency can be estimated as 10^(9) times that of the entanglement purification protocols using two copies of entangled states when one uses the spontaneous parametric down-conversion sources.Our work may have the potential to be implemented as a part of full repeater protocols.
基金supported by the National Key Research and Development Program of China(2017YFA0304100)National Natural Science Foundation of China(11374288,11774335,61327901,11474268,11325419 and 11504253)+2 种基金the Key Research Program of Frontier Sciences,Chinese Academy of Sciences(QYZDY-SSW-SLH003)the Fundamental Research Funds for the Central UniversitiesAnhui Initiative in Quantum Information Technologies(AHY020100 and AHY060300)
文摘Quantum nonlocality and quantum contextuality are the most curious properties that change our understanding of nature, and were observed independently in recent decades. One important question is whether both properties can be observed simultaneously. In this paper, we show that in a qutrit-qutrit system we can observe quantum nonlocality and quantum contextuality at the same time. From the perspective of quantum information, our experiment proves in principle that the two resources, quantum nonlocality and quantum contextuality, can be utilized simultaneously.
基金This work was supported by the National Natural Science Foundation of China(11734015,11704371,11821404,11774335,61327901,and 11874345)the National Key Research and Development Program of China(2017YFA0304100)+2 种基金the Anhui Initiative in Quantum Information Technologies(AHY070000)Key Research Program of Frontier Sciences,CAS(QYZDY-SSW-SLH003)the Fundamental Research Funds for the Central Universities(WK2030020019).
文摘Nonlocal correlation plays an important role in device independent quantum information processing.The stan-dard Bell nonlocality has been well studied with single local hidden variables,however the nonlocal correlations in general networks with several independent quantum sources and distant observers have been far less explored.Here,by using three independent entangled photon sources and recently constructed nonlinear Bell inequalities,we experimentally test the nonlocal correlations in the network scenario with different topologies.The violation of the inequalities can be obtained simply with separate measurements,which is much more favourable from the practical point of view.Our experiment results show a violation as 0.7779±0.0093 for the star network,and 0.7303±0.0024 for the chain network.Furthermore,we demonstrate that more measurement settings for each observer can bound more information against an eavesdropper.
基金This work was supported by the National Key Re-search and Development Program of China(No.2021YFE0113100),NSFC(No.11734015,No.11874345,No.11821404,No.11904357,No.12174367,No.12204458,No.12205219,and No.17326616)the Shanghai Municipal Science and Technology Fundamental Project(No.21JC1405400)+2 种基金the Fun-damental Research Funds for the Central Universities,USTC Tang Schol-arship,Science and Technological Fund of Anhui Province for Outstand-ing Youth(2008085J02)Science and Technological Fund of Anhui Province(2208085QA12)China Postdoctoral Science Foundation(2021M700138,BX2021289).
文摘Incompatible measurements are of fundamental importance to re-vealing the peculiar features of quantum theory,and are also use-ful resources in various quantum information tasks.In this work,we investigate the quantum incompatibility of mutually unbiased bases(MUBs)within the operational framework of quantum resource the-ory,and report an experimental validation via the task of state dis-crimination.In particular,we construct an experimentally friendly witness to detect incompatible MUBs,based on the probability of cor-rectly discriminating quantum states.Furthermore,we prove that the noise robustness of MUBs can be retrieved from violating the above witness.Finally,we experimentally test the incompatibility of MUBs of dimensionality ranging from 2 to 4,and demonstrate that it is more robust to noise,as either the dimensionality of measurements or the number of MUBs increases.Our results may aid the exploration of the essential roles of incompatible measurements in both theoretical and practical applications in quantum information.
