Single-photon entanglement(SPE) is an important source in quantum communication. In this paper, we put forward a single-photon-assisted noiseless linear amplification protocol to protect the SPE of an arbitrary polari...Single-photon entanglement(SPE) is an important source in quantum communication. In this paper, we put forward a single-photon-assisted noiseless linear amplification protocol to protect the SPE of an arbitrary polarization–time-bin qudit from the photon transmission loss caused by the practical channel noise. After the amplification, the fidelity of the SPE can be effectively increased. Meanwhile, the encoded polarization–time-bin features of the qudit can be well preserved. The protocol can be realized under the current experimental conditions. Moreover, the amplification protocol can be extended to resist complete photon loss and partial photon loss during the photon transmission. After the amplification, we can not only increase the fidelity of the target state, but also solve the decoherence problem simultaneously. Based on the above features, our amplification protocol may be useful in future quantum communication.展开更多
High-dimensional quantum resources provide the ability to encode several bits of information on a single photon,which can particularly increase the secret key rate rate of quantum key distribution(QKD)systems.Recently...High-dimensional quantum resources provide the ability to encode several bits of information on a single photon,which can particularly increase the secret key rate rate of quantum key distribution(QKD)systems.Recently,a practical four-dimensional QKD scheme based on time-bin quantum photonic state,only with two single-photon avalanche detectors as measurement setup,has been proven to have a superior performance than the qubit-based one.In this paper,we extend the results to our proposed eight-dimensional scheme.Then,we consider two main practical factors to improve its secret key bound.Concretely,we take the afterpulse effect into account and apply a finite-key analysis with the intensity fluctuations.Our secret bounds give consideration to both the intensity fluctuations and the afterpulse effect for the high-dimensional QKD systems.Numerical simulations show the bound of eight-dimensional QKD scheme is more robust to the intensity fluctuations but more sensitive to the afterpulse effect than the four-dimensional one.展开更多
We design proposals to generate a remote Greenberger-Horne-Zeilinger（GHZ） state and a W state of nitrogenvacancy（NV） centers coupled to microtoroidal resonators（MTRs） through noisy channels by utilizing time-bin...We design proposals to generate a remote Greenberger-Horne-Zeilinger（GHZ） state and a W state of nitrogenvacancy（NV） centers coupled to microtoroidal resonators（MTRs） through noisy channels by utilizing time-bin encoding processes and fast-optical-switch-based polarization rotation operations.The polarization and phase noise induced by noisy channels generally affect the time of state generation but not its success probability and fidelity.Besides,the above proposals can be generalized to n-qubit between two or among n remote nodes with success probability unity under ideal conditions.Furthennore,the proposals are robust for regular noise-changeable channels for the n-node case.This method is also useful in other remote quantum information processing tasks through noisy channels.展开更多
Measurement-device-independent quantum key distribution （MDI-QKD） eliminates all loopholes on detection. 3 loss in the final key for the Previous experiments of time-bin phase-encoding MDI-QKD allow a factor of inc...Measurement-device-independent quantum key distribution （MDI-QKD） eliminates all loopholes on detection. 3 loss in the final key for the Previous experiments of time-bin phase-encoding MDI-QKD allow a factor of incapability of identifying two successive detection events by a single photon detector. Here we propose a new scheme to realize the time-bin phase-encoding MDI-QKD. The polarization states are used to generate the time bins and the phase-encoding states. The factor of loss in the final key is eliminated by using four single photon detectors at the measurement site. We show the feasibility of our scheme with a proof-of-principle experimental demonstration. The phase reference frame is rotated extremely slowly with only passive stabilization measures. The quantum bit error rate can reach 0.8% in the Z-basis and 26.2% in the X-basis.展开更多
Quantum communication networks,such as quantum key distribution(QKD)networks,typically employ the measurement-resend mechanism between two users using quantum communication devices based on different quantum encoding ...Quantum communication networks,such as quantum key distribution(QKD)networks,typically employ the measurement-resend mechanism between two users using quantum communication devices based on different quantum encoding types.To achieve direct communication between the devices with different quantum encoding types,in this paper,we propose encoding conversion schemes between the polarization bases(rectilinear,diagonal and circular bases)and the time-bin phase bases(two phase bases and time-bin basis)and design the quantum encoding converters.The theoretical analysis of the encoding conversion schemes is given in detail,and the basis correspondence of encoding conversion and the property of bit flip are revealed.The conversion relationship between polarization bases and time-bin phase bases can be easily selected by controlling a phase shifter.Since no optical switches are used in our scheme,the converter can be operated with high speed.The converters can also be modularized,which may be utilized to realize miniaturization in the future.展开更多
Hyperentanglement has attracted considerable attention recently because of its high-capacity for long- distance quantum communication. In this study, we present a hyperentanglement concentration pro- tocol （hyper-ECP...Hyperentanglement has attracted considerable attention recently because of its high-capacity for long- distance quantum communication. In this study, we present a hyperentanglement concentration pro- tocol （hyper-ECP） for nonlocal three-photon systems in the polarization, spatial-mode, and time- bin partially hyperentangled Greenberger-Horne-Zeilinger （GHZ） states using the Schmidt projection method. In our hyper-ECP, the three distant parties must perform the parity-check measurements on the polarization, spatial-mode, and time-bin degrees of freedom, respectively, using linear optical ele- ments and Pockels cells, and only two identical nonlocal photon systems are required. This hyper-ECP can be directly extended to the N-photon hyperentangled GHZ states, and the success probability of this general hyper-ECP for a nonlocal N-photon system is the optimal one, regardless of the photon number N.展开更多
We propose a scheme of entangling two photons from two separated sources.Our proposal which is inspired by the time-bin entanglement developed recently,provides a novel alternative for revealing contradiction between ...We propose a scheme of entangling two photons from two separated sources.Our proposal which is inspired by the time-bin entanglement developed recently,provides a novel alternative for revealing contradiction between quantum nonlocality and local realism based on two independent single photon sources.展开更多
基金Project supported by the National Natural Science Foundation of China(Grant Nos.11474168 and 11747161)the Priority Academic Program Development of Jiangsu Higher Education Institutions,Chinathe China Postdoctoral Science Foundation(Grant No.2018M642293)
文摘Single-photon entanglement(SPE) is an important source in quantum communication. In this paper, we put forward a single-photon-assisted noiseless linear amplification protocol to protect the SPE of an arbitrary polarization–time-bin qudit from the photon transmission loss caused by the practical channel noise. After the amplification, the fidelity of the SPE can be effectively increased. Meanwhile, the encoded polarization–time-bin features of the qudit can be well preserved. The protocol can be realized under the current experimental conditions. Moreover, the amplification protocol can be extended to resist complete photon loss and partial photon loss during the photon transmission. After the amplification, we can not only increase the fidelity of the target state, but also solve the decoherence problem simultaneously. Based on the above features, our amplification protocol may be useful in future quantum communication.
基金Project supported by the National Key Research and Development Program of China(Grant No.2020YFA0309702)the National Natural Science Foundation of China(Grant Nos.62101597,61605248,61675235,and 61505261)+2 种基金the China Postdoctoral Science Foundation(Grant No.2021M691536)the Natural Science Foundation of Henan Province,China(Grant Nos.202300410534 and 202300410532)the Anhui Initiative Fund in Quantum Information Technologies。
文摘High-dimensional quantum resources provide the ability to encode several bits of information on a single photon,which can particularly increase the secret key rate rate of quantum key distribution(QKD)systems.Recently,a practical four-dimensional QKD scheme based on time-bin quantum photonic state,only with two single-photon avalanche detectors as measurement setup,has been proven to have a superior performance than the qubit-based one.In this paper,we extend the results to our proposed eight-dimensional scheme.Then,we consider two main practical factors to improve its secret key bound.Concretely,we take the afterpulse effect into account and apply a finite-key analysis with the intensity fluctuations.Our secret bounds give consideration to both the intensity fluctuations and the afterpulse effect for the high-dimensional QKD systems.Numerical simulations show the bound of eight-dimensional QKD scheme is more robust to the intensity fluctuations but more sensitive to the afterpulse effect than the four-dimensional one.
基金supported by the National Natural Science Foundation of China(Grant Nos.11264042,61465013,11465020,and 11165015)the Program for Chun Miao Excellent Talents of Jilin Provincial Department of Education(Grant No.201316)the Talent Program of Yanbian University of China(Grant No.950010001)
文摘We design proposals to generate a remote Greenberger-Horne-Zeilinger（GHZ） state and a W state of nitrogenvacancy（NV） centers coupled to microtoroidal resonators（MTRs） through noisy channels by utilizing time-bin encoding processes and fast-optical-switch-based polarization rotation operations.The polarization and phase noise induced by noisy channels generally affect the time of state generation but not its success probability and fidelity.Besides,the above proposals can be generalized to n-qubit between two or among n remote nodes with success probability unity under ideal conditions.Furthennore,the proposals are robust for regular noise-changeable channels for the n-node case.This method is also useful in other remote quantum information processing tasks through noisy channels.
基金Supported by the National Natural Science Foundation of China under Grant Nos 11304391,11674397 and 61671455the Program for New Century Excellent Talents in University of China
文摘Measurement-device-independent quantum key distribution （MDI-QKD） eliminates all loopholes on detection. 3 loss in the final key for the Previous experiments of time-bin phase-encoding MDI-QKD allow a factor of incapability of identifying two successive detection events by a single photon detector. Here we propose a new scheme to realize the time-bin phase-encoding MDI-QKD. The polarization states are used to generate the time bins and the phase-encoding states. The factor of loss in the final key is eliminated by using four single photon detectors at the measurement site. We show the feasibility of our scheme with a proof-of-principle experimental demonstration. The phase reference frame is rotated extremely slowly with only passive stabilization measures. The quantum bit error rate can reach 0.8% in the Z-basis and 26.2% in the X-basis.
基金supported by the National Natural Science Foundation of China(Grant No.62001440).
文摘Quantum communication networks,such as quantum key distribution(QKD)networks,typically employ the measurement-resend mechanism between two users using quantum communication devices based on different quantum encoding types.To achieve direct communication between the devices with different quantum encoding types,in this paper,we propose encoding conversion schemes between the polarization bases(rectilinear,diagonal and circular bases)and the time-bin phase bases(two phase bases and time-bin basis)and design the quantum encoding converters.The theoretical analysis of the encoding conversion schemes is given in detail,and the basis correspondence of encoding conversion and the property of bit flip are revealed.The conversion relationship between polarization bases and time-bin phase bases can be easily selected by controlling a phase shifter.Since no optical switches are used in our scheme,the converter can be operated with high speed.The converters can also be modularized,which may be utilized to realize miniaturization in the future.
基金This work was supported by the National Natural Science Foundation of China under Grants Nos. 11604226, 11674033, and 11474026, and the Science and Technology Program Foundation of the Beijing Municipal Commission of Education of China under Grant No. KM201710028005.
文摘Hyperentanglement has attracted considerable attention recently because of its high-capacity for long- distance quantum communication. In this study, we present a hyperentanglement concentration pro- tocol （hyper-ECP） for nonlocal three-photon systems in the polarization, spatial-mode, and time- bin partially hyperentangled Greenberger-Horne-Zeilinger （GHZ） states using the Schmidt projection method. In our hyper-ECP, the three distant parties must perform the parity-check measurements on the polarization, spatial-mode, and time-bin degrees of freedom, respectively, using linear optical ele- ments and Pockels cells, and only two identical nonlocal photon systems are required. This hyper-ECP can be directly extended to the N-photon hyperentangled GHZ states, and the success probability of this general hyper-ECP for a nonlocal N-photon system is the optimal one, regardless of the photon number N.
文摘We propose a scheme of entangling two photons from two separated sources.Our proposal which is inspired by the time-bin entanglement developed recently,provides a novel alternative for revealing contradiction between quantum nonlocality and local realism based on two independent single photon sources.
