The various aspects of the Kochen-Specker (KS) theorem with single photons were presented. A complex formulation, designed by the KS theorem, was used to present the compatibility of noncontextual hidden variables (NCHV) with quantum mechanics. A two-qubit system was formed with the help of polarization and path degrees of single photon.
Huang Yun-Feng;Li Chuan-Feng;Zhang Yong-Sheng;Pan Jian-Wei;Guo Guang-Can
Physical Review Letters
2003
Enhancement of entanglement is necessary for most quantum communication protocols many of which are defined in Hilbert spaces larger than 2. In this work we present the experimental realization of entanglement concentration of orbital angular momentum entangled photons. We investigate the specific case of three dimensions and the possibility of generating different entangled states out of an initial state. The results presented here are of importance for pure states as well as for mixed states. © 2003 The American Physical Society.
Vaziri Alipasha;Pan Jian-Wei;Jennewein Thomas;Zeilinger Anton;Weihs Gregor
Physical Review Letters
2003
We experimentally entangle freely propagating particles that never physically interacted with one another or which have never been dynamically coupled by any other means. This demonstrates that quantum entanglement requires the entangled particles neither to come from a common source nor to have interacted in the past. In our experiment we take two pairs of polarization entangled photons and subject one photon from each pair to a Bell-state measurement. This results in projecting the other two outgoing photons into an entangled state. © 1998 The American Physical Society.
Pan Jian-Wei;Bouwmeester Dik;Weinfurter Harald;Zeilinger Anton
Physical Review Letters
1998
The generalization of the quantum-secret-sharing (QSS) of Hillery, Bužek and Berthiaume (HBB) into arbitrary multiparties was analyzed. It was observed that in the HBB QSS scheme the secret information is shared in the parity of binary strings formed by the measured outcomes of the participants. The favored-measuring-basis QSS scheme was developed from the Lo-Chau-Ardehali technique where all the participants choose their measuring-basis asymmetrically. The measuring-basis-encrypted QSS scheme was developed from the Hwang-Koh-Han technique where all participants choose their measuring basis according to a control key. The results show that both schemes are asymptotically 100% in efficiency.
Xiao Li;Long Gui Lu;Deng Fu-Guo;Pan Jian-Wei
Physical Review A Atomic Molecular and Optical Physics
2004
Universal logic gates for two quantum bits (qubits) form an essential ingredient of quantum information processing. However, photons, one of the best candidates for qubits, suffer from a lack of strong nonlinear coupling, which is required for quantum logic operations. Here we show how this drawback can be overcome by reporting a proof-of-principle experimental demonstration of a nondestructive controlled-NOT (CNOT) gate for two independent photons using only linear optical elements in conjunction with single-photon sources and conditional dynamics. Moreover, we exploit the CNOT gate to discriminate all four Bell states in a teleportation experiment. © 2005 The American Physical Society.
Zhao Zhi;Zhang An-Ning;Chen Yu-Ao;Zhang Han;Du Jiang-Feng;Yang Tao;Pan Jian-Wei
Physical Review Letters
2005
We report free-space distribution of entangled photon pairs over a noisy ground atmosphere of 13 km. It is shown that the desired entanglement can still survive after both entangled photons have passed through the noisy ground atmosphere with a distance beyond the effective thickness of the aerosphere. This is confirmed by observing a spacelike separated violation of Bell inequality of 2.45 ± 0.09. On this basis, we exploit the distributed entangled photon source to demonstrate the Bennett-Brassard 1984 quantum cryptography scheme. The distribution distance of entangled photon pairs achieved in the experiment is for the first time well beyond the effective thickness of the aerosphere, hence presenting a significant step towards satellite-based global quantum communication. © 2005 The American Physical Society.
Peng Cheng-Zhi;Yang Tao;Bao Xiao-Hui;Zhang Jun;Jin Xian-Min;Feng Fa-Yong;Yang Bin;Yang Jian;Yin Juan;Zhang Qiang;Li Nan;Tian Bao-Li;Pan Jian-Wei
Physical Review Letters
2005
A stable passively synchronized femtosecond laser has been realized by coupling two 1.3 W mode-locked Ti:sapphire lasers with a Kerr medium. An ultralong tolerance of 10 μm for the cavity length mismatch and a timing jitter of less than 0.4 fs were obtained. The relative carrier-envelope phase slip was directly observed by measuring the heterodyne output between the two lasers. © 2005 Optical Society of America.
Tian Jinrong;Wei Zhiyi;Wang Peng;Han Hainian;Zhang Jun;Zhao Linghui;Wang Zhaohua;Zhang Jie;Yang Tao;Pan Jianwei
Optics Letters
2005
Quantum secret sharing (QSS) and third-man quantum cryptography (TQC) are essential for advanced quantum communication; however, the low intensity and fragility of the multiphoton entanglement source in previous experiments have made their realization an extreme experimental challenge. Here, we develop and exploit an ultrastable high intensity source of four-photon entanglement to report an experimental realization of QSS and TQC. The technology developed in our experiment will be important for future multiparty quantum communication. © 2005 The American Physical Society.
Chen Yu-Ao;Zhang An-Ning;Zhao Zhi;Zhou Xiao-Qi;Lu Chao-Yang;Peng Cheng-Zhi;Yang Tao;Pan Jian-Wei
Physical Review Letters
2005
In principle, quantum key distribution (QKD) can be used to make unconditionally secure private communication. However, the security of the existing real system for QKD needs to be carefully examined. Actually, the existing experiments based on weak coherent states are not secure under photon-number-splitting attack. Fortunately, the decoy-state method and the entanglement-distribution method can be used to realize the unconditionally secure QKD based on real-life systems with existing technology. © Higher Education Press and Springer-Verlag 2006.
Wang Xiang-Bin;Peng Cheng-Zhi;Ying Hao;Ma Huai-Xing;Yang Tao;Pan Jian-Wei
Frontiers of Physics in China
2006
The existing theory of decoy-state quantum cryptography assumes the exact control of each state from Alice's source. Such exact control is impossible in practice. We develop the theory of decoy-state method so that it is unconditionally secure even if there are state errors of sources, if the range of a few parameters in the states are known. This theory simplifies the practical implementation of the decoy-state quantum key distribution because the unconditional security can be achieved with a slightly shortened final key, even though the small errors of pulses are not corrected. © 2008 The American Physical Society.
Wang Xiang-Bin;Peng Cheng-Zhi;Yang Lin;Pan Jian-Wei;Zhang Jun
Physical Review A Atomic Molecular and Optical Physics
2008