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

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

Pan Jianwei

CLEO Europe Eqec 2009 European Conference on Lasers and Electro Optics and the European Quantum Electronics Conference

2009

In recent years, there has been heightened interest in quantum teleportation, which allows for the transfer of unknown quantum states over arbitrary distances. Quantum teleportation not only serves as an essential ingredient in long-distance quantum communication, but also provides enabling technologies for practical quantum computation. Of particular interest is the scheme proposed by D. Gottesman and I. L. Chuang [(1999) Nature 402:390- 393], showing that quantum gates can be implemented by teleporting qubits with the help of some special entangled states. Therefore, the construction of a quantum computer can be simply based on some multiparticle entangled states, Bell-state measurements, and single-qubit operations. The feasibility of this scheme relaxes experimental constraints on realizing universal quantum computation. Using two different methods, we demonstrate the smallest nontrivial module in such a scheme-a teleportationbased quantum entangling gate for two different photonic qubits. One uses a high-fidelity six-photon interferometer to realize controlled-NOT gates, and the other uses four-photon hyperentanglement to realize controlled-Phase gates. The results clearly demonstrate the working principles and the entangling capability of the gates. Our experiment represents an important step toward the realization of practical quantum computers and could lead to many further applications in linear optics quantum information processing.

Gao Wei-Bo;Lu Chao-Yang;Dai Han-Ning;Zhang Qiang;Zhao Bo;Peng Cheng-Zhi;Chen Zeng-Bing;Chen Yu-Ao;Pan Jian-Wei;Goebel Alexander M.;Wagenknecht Claudia

Proceedings of the National Academy of Sciences of the United States of America

2010

We have demonstrated a metropolitan all-pass quantum communication network in field fiber for four nodes. Any two nodes of them can be connected in the network to perform quantum key distribution (QKD). An optical switching module is presented that enables arbitrary 2-connectivity among output ports. Integrated QKD terminals are worked out, which can operate either as a transmitter, a receiver, or even both at the same time. Furthermore, an additional link in another city of 60 km fiber (up to 130 km) is seamless integrated into this network based on a trusted relay architecture. On all the links, we have implemented protocol of decoy state scheme. All of necessary electrical hardware, synchronization, feedback control, network software, execution of QKD protocols are made by tailored designing, which allow a completely automatical and stable running. Our system has been put into operation in Hefei in August 2009, and publicly demonstrated during an evaluation conference on quantum network organized by the Chinese Academy of Sciences on August 29, 2009. Real-time voice telephone with one-time pad encoding between any two of the five nodes (four all-pass nodes plus one additional node through relay) is successfully established in the network within 60km. © 2010 Optical Society of America.

Chen Teng-Yun;Wang Jian;Liang Hao;Liu Yang;Jiang Xiao;Wang Yuan;Wan Xu;Cai Wen-Qi;Ju Lei;Chen Luo-Kan;Wang Liu-Jun;Gao Yuan;Chen Kai;Peng Cheng-Zhi;Chen Zeng-Bing;Pan Jian-Wei;Liu Wei-Yue

Optics Express

2010

Synchronized femtosecond lasers have been widely used in pump-probe experiments, optical frequency metrology, generation of THz wave, etc. This chapter describes a new passive synchronization scheme for two independent Ti: sapphire lasers with superior robustness and subfemtosecond timing jitter. The synchronization operation could be started by hand, and the synchronization sustained more than 8 hours with a least timing jitter of 0.4 fs. The tolerance of the cavity length mismatch is large enough to start the synchronization by hand. The correlation measurement revealed its timing jitter was less than 1 fs. The relative carrier-envelope phase slip between the laser pulses was detected by a beat frequency measurement without frequency conversion, which paved the way for phase-locking the synchronized femtosecond lasers. © 2006 Elsevier B.V. All rights reserved.

Tian Jinrong;Wei Zhiyi;Wang Peng;Han Hainian;Wang Zhaohua;Zhang Jie;Yang Tao;Pan Jianwei

Femtochemistry VII

2006

Quantum physics allows for unconditionally secure communication between parties that trust each other. However, when the parties do not trust each other such as in the bit commitment scenario, quantum physics is not enough to guarantee security unless extra assumptions are made. Unconditionally secure bit commitment only becomes feasible when quantum physics is combined with relativistic causality constraints. Here we experimentally implement a quantum bit commitment protocol with relativistic constraints that offers unconditional security. The commitment is made through quantum measurements in two quantum key distribution systems in which the results are transmitted via free-space optical communication to two agents separated with more than 20 km. The security of the protocol relies on the properties of quantum information and relativity theory. In each run of the experiment, a bit is successfully committed with less than 5.68×10-2 cheating probability. This demonstrates the experimental feasibility of quantum communication with relativistic constraints. © 2014 American Physical Society.

Liu Yang;Cao Yuan;Liao Sheng-Kai;Wang Jian;Cui Ke;Li Yu-Huai;Lin Ze-Hong;Sun Qi-Chao;Li Dong-Dong;Zhang Hong-Fei;Zhao Yong;Chen Teng-Yun;Peng Cheng-Zhi;Zhang Qiang;Pan Jian-Wei;Curty Marcos;Cabello Ad\u00e1n

Physical Review Letters

2014

Pan Jian-Wei

Optics Infobase Conference Papers

2009