Quantum repeater Single-photon quantum repeater L.M. Duan et al., Nature 414, 413 (2001) tWo-photon quantum repeater B. Zhao et al., Phys. Rev. Lett. 98, 240502(2007) Z B Chen et al., Phys. Rev. A 76, 022329 (2007)
Quantum repeater Single-photon quantum repeater two-photon quantum repeater L.M. Duan et al., Nature 414, 413 (2001) B. Zhao et al., Phys. Rev. Lett. 98, 240502 (2007) Z. B. Chen et al., Phys. Rev. A 76, 022329 (2007)
由于纠缠只能通过局域产生,然后通过信道发送粒 子的方式来共享。这样,纠缠粒子和环境的相互作 用就不可避免。本来处于最大纠缠态的粒子对经信 道传输后就会发生退相干,这种退相干通常有两种 结果: 由纯的最大纠缠态变成混合态纠缠纯化 Entanglement purification 由最大纠缠态变成部分纠缠态 纠缠浓缩 Entanglement concentration
由于纠缠只能通过局域产生，然后通过信道发送粒 子的方式来共享。这样，纠缠粒子和环境的相互作 用就不可避免。本来处于最大纠缠态的粒子对经信 道传输后就会发生退相干，这种退相干通常有两种 结果: 纠缠纯化 由最大纠缠态变成部分纠缠态 纠缠浓缩 由纯的最大纠缠态变成混合态 Entanglement concentration Entanglement purification
two-photon entanglement purification and concentration (a) C. H. Bennett, et al., Phys. Rev. Lett. 76, 722(1996) (b) D. Deutsch et al., Phys. Rev. Lett. 77, 2818(1996) (e) J.W. Pan et al., Nature(London)410, 1067(2001) (d)C. Simon, J.W. Pan, Phys. Rev. Lett. 89, 257901(2002) (e) Y.B. Sheng, F. G. Deng, H. Y. Zhou, Phys. Rev. A77 042308(2008) (f) Y.B. Sheng, F G. Deng, Phys. Rev. A81, 032307(2010) (a )C.H. Bennett, et al., Phys. Rev. A 53, 2046(1996) (b)T. Yamamoto, et al., Phys. Rev. A 64, 012304(2001) (c)Z Zhao, J.W. Pan, M.S. Zhan, Phys. Rev. A 64,014301(2001) (d,)Y.B. Sheng, F. G. Deng, H. Y. Zhou, Phys. Rev. A77, 062325 (2008)
two-photon entanglement purification and concentration (a) C. H. Bennett, et al., Phys. Rev. Lett. 76, 722 (1996). (b) D. Deutsch et al., Phys. Rev. Lett. 77, 2818 (1996). (c) J. W. Pan et al., Nature (London) 410, 1067 (2001). (d) C. Simon, J. W. Pan, Phys. Rev. Lett. 89, 257901 (2002). (e) Y. B. Sheng, F. G. Deng, H. Y. Zhou, Phys. Rev. A 77, 042308 (2008). (f) Y. B. Sheng, F. G. Deng, Phys. Rev. A 81, 032307 (2010). (a’) C. H. Bennett, et al., Phys. Rev. A 53, 2046 (1996). (b’) T. Yamamoto, et al., Phys. Rev. A 64, 012304 (2001). (c’) Z. Zhao, J. W. Pan, M. S. Zhan, Phys. Rev. A 64, 014301 (2001). (d’) Y. B. Sheng, F. G. Deng, H. Y. Zhou, Phys. Rev. A 77, 062325 (2008)
Experiment Realization b Alice Delay Bob PolBrewster Pol F Windows BBO PBS UV A-4 RM AHP-D, Pol [Z. Zhao et al, Phys. Rev. Lett. 90, 207901(2003).] [T. Yamamoto et al., Nature 421, 343(2003)
Single-photon entanglement purification and concentration After entanglement generation yab=(aa+Beiab b )oy Partial entanglement state (a)N. Sangouard, C. Simon, T. Coudreau, N. Gisin Purification of single-photon entanglement with linear optics Phys.RevA78,50301(R)(2008) (b)YB. Sheng, F G. Deng, H.Y. Zhou, Single-photon entanglement concentration for long-distance quantum communication. Quantum information computation 10, 272(2010)
Single-photon entanglement purification and concentration (a) N. Sangouard, C. Simon, T. Coudreau, N. Gisin, Purification of single-photon entanglement with linear optics, Phys. Rev. A 78, 50301(R) (2008). (b) Y. B. Sheng, F. G. Deng, H. Y. Zhou, Single-photon entanglement concentration for long-distance quantum communication, Quantum information & computation 10, 272 (2010). After entanglement generation: Partial entanglement state