We propose a scheme capable of performing complete Bell-state analysis for a single-photon hybrid entangled state.Our single-photon state is encoded in both polarization and frequency degrees of freedom.The setup of t...We propose a scheme capable of performing complete Bell-state analysis for a single-photon hybrid entangled state.Our single-photon state is encoded in both polarization and frequency degrees of freedom.The setup of the scheme is composed of polarizing beam splitters,half wave plates,frequency shifters,and independent wavelength division multiplexers,which are feasible using current technology.We also show that with this setup we can perform complete two-photon Bell-state analysis schemes for polarization degrees of freedom.Moreover,it can also be used to perform the teleportation scheme between different degrees of freedom.This setup may allow extensive applications in current quantum communications.展开更多
We present an efficient entanglement purification protocol （EPP） with controlled-not （CNOT） gates and linear optics. With the CNOT gates, our EPP can reach a higher fidelity than the conventional one. Moreover, it...We present an efficient entanglement purification protocol （EPP） with controlled-not （CNOT） gates and linear optics. With the CNOT gates, our EPP can reach a higher fidelity than the conventional one. Moreover, it does not require the fidelity of the initial mixed state to satisfy 1 2. If the initial state is not entangled, it still can be purified. With the linear optics, this protocol can get pure maximally entangled pairs with some probabilities. Meanwhile, it can be used to purify the entanglement between the atomic ensembles in distant locations. This protocol may be useful in long-distance quantum communication.展开更多
By using the measure of von Neumann entropy, we numerically investigate quantum entanglement of an electron moving in the one-dimensional Harper model and in the one-dimensional slowly varying potential model. The del...By using the measure of von Neumann entropy, we numerically investigate quantum entanglement of an electron moving in the one-dimensional Harper model and in the one-dimensional slowly varying potential model. The delocalized and localized eigenstates can be distinguished by von Neumann entropy of the individual eigenstates.There are drastic decreases in von Neumann entropy of the individual eigenstates at mobility edges. In the curve of the spectrum averaged von Neumann entropy as a function of potential parameter λ, a sharp transition exists at the metal-insulator transition point λc = 2. It is found that the von Neumann entropy is a good quantity to reflect localization and metal-insulator transition.展开更多
基金Project supported by the National Natural Science Foundation of China (Grant Nos. 11104159,61201164,and 61271238)the Open Research Fund Program of the State Key Laboratory of Low-Dimensional Quantum Physics Scientific,Tsinghua University,China+2 种基金the Open Research Fund Program of National Laboratory of Solid State Microstructures,Nanjing University,China (Grant Nos. M25020 and M25022)the Priority Academic Development Program of Jiangsu Higher Education Institutions,China,the Open Research Fund of National Mobile Communications Research Laboratory of Southeast University,China (Grant No. 2011D05)the Specialized Research Fund for the Doctoral Program of Higher Education of China (Grant No. 20123223110003)
文摘We propose a scheme capable of performing complete Bell-state analysis for a single-photon hybrid entangled state.Our single-photon state is encoded in both polarization and frequency degrees of freedom.The setup of the scheme is composed of polarizing beam splitters,half wave plates,frequency shifters,and independent wavelength division multiplexers,which are feasible using current technology.We also show that with this setup we can perform complete two-photon Bell-state analysis schemes for polarization degrees of freedom.Moreover,it can also be used to perform the teleportation scheme between different degrees of freedom.This setup may allow extensive applications in current quantum communications.
基金Project supported by the National Natural Science Foundation of China (Grant Nos. 11104159 and 10904074)the Scientific Research Foundation of Nanjing University of Posts and Telecommunications, China (Grant No. NY211008)+2 种基金the University Natural Science Research Foundation of Jiangsu Province, China (Grant No. 11KJA510002)the Open Research Fund of Key Labof Broadband Wireless Communication and Sensor Network Technology (Nanjing University of Posts and Telecommunications) of Ministry of Education, Chinathe Priority Academic Program Development Fund of Jiangsu Higher Education Institutions,China
文摘We present an efficient entanglement purification protocol （EPP） with controlled-not （CNOT） gates and linear optics. With the CNOT gates, our EPP can reach a higher fidelity than the conventional one. Moreover, it does not require the fidelity of the initial mixed state to satisfy 1 2. If the initial state is not entangled, it still can be purified. With the linear optics, this protocol can get pure maximally entangled pairs with some probabilities. Meanwhile, it can be used to purify the entanglement between the atomic ensembles in distant locations. This protocol may be useful in long-distance quantum communication.
基金Supported by the National Natural Science Foundation of China under Grant Nos 90203009 and 10175035, the Natural Science Foundation of Jiangsu Province of China under Grant No BK2001107, and the Excellent Young Teacher Program of the Ministry of Education of China.
文摘By using the measure of von Neumann entropy, we numerically investigate quantum entanglement of an electron moving in the one-dimensional Harper model and in the one-dimensional slowly varying potential model. The delocalized and localized eigenstates can be distinguished by von Neumann entropy of the individual eigenstates.There are drastic decreases in von Neumann entropy of the individual eigenstates at mobility edges. In the curve of the spectrum averaged von Neumann entropy as a function of potential parameter λ, a sharp transition exists at the metal-insulator transition point λc = 2. It is found that the von Neumann entropy is a good quantity to reflect localization and metal-insulator transition.
