Bell inequality is an important resource in the quantum information theory, which can be applied to guarantee security of the device independent quantum information protocols. By utilizing the quantum weak measurement...Bell inequality is an important resource in the quantum information theory, which can be applied to guarantee security of the device independent quantum information protocols. By utilizing the quantum weak measurement technology, we propose the Chain inequality violation with three parties, and the analysis result demonstrates that double Chain inequality violation can be observed in the case of Alice and Bob have two different measurement bases.Since the weak measurement model can be assumed to be an eavesdropping model, our analysis model may be applied to analyze security of the device independent quantum information protocols.展开更多
This paper introduces the concept and motivates the use of finite-interval based measures for physically realizable and measurable quantities, which we call -measures. We demonstrate the utility and power of -measures...This paper introduces the concept and motivates the use of finite-interval based measures for physically realizable and measurable quantities, which we call -measures. We demonstrate the utility and power of -measures by illustrating their use in an interval-based analysis of a prototypical Bell’s inequality in the measurement of the polarization states of an entangled pair of photons. We show that the use of finite intervals in place of real-numbered values in the Bell inequality leads to reduced violations. We demonstrate that, under some conditions, an interval-based but otherwise classically calculated probability measure can be made to arbitrarily closely approximate its quantal counterpart. More generally, we claim by heuristic arguments and by formal analogy with finite-state machines that -measures can provide a more accurate model of both classical and quantal physical property values than point-like, real numbers—as originally proposed by Tuero Sunaga in 1958.展开更多
Quantum secure direct communication(QSDC) is an important quantum communication branch, which realizes the secure information transmission directly without encryption and decryption processes.Recently, two table-top e...Quantum secure direct communication(QSDC) is an important quantum communication branch, which realizes the secure information transmission directly without encryption and decryption processes.Recently, two table-top experiments have demonstrated the principle of QSDC. Here, we report the first long-distance QSDC experiment, including the security test, information encoding, fiber transmission and decoding. After the fiber transmission of 0.5 km, quantum state fidelities of the two polarization entangled Bell states are 91% and 88%, respectively, which are used for information coding. We theoretically analyze the performance of the QSDC system based on current optical communication technologies,showing that QSDC over fiber links of several tens kilometers could be expected. It demonstrates the potential of long-distance QSDC and supports its future applications on quantum communication networks.展开更多
基金Supported by National Natural Science Foundation of China under Grant Nos.61675235,11304397National Key Research and Development Program of China under Grant No.2016YFA0302600
文摘Bell inequality is an important resource in the quantum information theory, which can be applied to guarantee security of the device independent quantum information protocols. By utilizing the quantum weak measurement technology, we propose the Chain inequality violation with three parties, and the analysis result demonstrates that double Chain inequality violation can be observed in the case of Alice and Bob have two different measurement bases.Since the weak measurement model can be assumed to be an eavesdropping model, our analysis model may be applied to analyze security of the device independent quantum information protocols.
文摘This paper introduces the concept and motivates the use of finite-interval based measures for physically realizable and measurable quantities, which we call -measures. We demonstrate the utility and power of -measures by illustrating their use in an interval-based analysis of a prototypical Bell’s inequality in the measurement of the polarization states of an entangled pair of photons. We show that the use of finite intervals in place of real-numbered values in the Bell inequality leads to reduced violations. We demonstrate that, under some conditions, an interval-based but otherwise classically calculated probability measure can be made to arbitrarily closely approximate its quantal counterpart. More generally, we claim by heuristic arguments and by formal analogy with finite-state machines that -measures can provide a more accurate model of both classical and quantal physical property values than point-like, real numbers—as originally proposed by Tuero Sunaga in 1958.
基金supported by National Key R&D Program of China (2017YFA0303700)the National Basic Research Program of China (2013CB328700)+1 种基金the National Natural Science Foundation of China(61575102, 11474168 and 61621064)the Tsinghua University Initiative Scientific Research Program
文摘Quantum secure direct communication(QSDC) is an important quantum communication branch, which realizes the secure information transmission directly without encryption and decryption processes.Recently, two table-top experiments have demonstrated the principle of QSDC. Here, we report the first long-distance QSDC experiment, including the security test, information encoding, fiber transmission and decoding. After the fiber transmission of 0.5 km, quantum state fidelities of the two polarization entangled Bell states are 91% and 88%, respectively, which are used for information coding. We theoretically analyze the performance of the QSDC system based on current optical communication technologies,showing that QSDC over fiber links of several tens kilometers could be expected. It demonstrates the potential of long-distance QSDC and supports its future applications on quantum communication networks.
