冷原子物理和量子信息学术讨论（PPT讲稿）Entanglement purification and faithful qubit transmission

第四届企圖薺原子物理和量子信息音年喾者学术讨论会 Entanglement purification and faithful qubit transmission Fu-Guo Deng{邓富国) Department of Physics, Beijing Normal University, Beijing 100875 2010.8.5, Dalian

Entanglement purification and faithful qubit transmission Fu-Guo Deng (邓 富 国) 第四届全国冷原子物理和量子信息青年学者学术讨论会 Department of Physics, Beijing Normal University, Beijing 100875 2010. 8. 5, Dalian

Outline 1. Motivation 2. Entanglement purification 3. Faithful qubit transmission 4. Summary

Outline 1. Motivation 2. Entanglement purification 3. Faithful qubit transmission 4. Summary

1. Motivation EPR-Source Both long distance quantum teleportation or global quantum key distribution need to distribute a certain supply of pairs of particles in a maximally entangled state to two distant users

1. Motivation

Source and transmitter Tracking laser TransmitterICCD telescope BBO High-power aser La gomera Alice on La alma Bob on Tenerife Polarization compensation Polarization compensation BN因 Time 4、团B ggang 岛心 Polarization analyser Polarization analyser R Ursin et al, Entanglement-based quantum communication over 144km University of vienna, Nature Physics 3: 481-484(2007)

R. Ursin et al，Entanglement-based quantum communication over 144km， University of Vienna，Nature Physics 3：481-484 (2007)

Long-distance quantum communication Quantum repeater Entanglement: a) Generation b) Distribution c)Purification d) Swapping e)Storage Briegel et al., Phys. Rev. Lett.81, 5932(1998)

Long-distance quantum communication: Quantum repeater Briegel et al., Phys. Rev. Lett. 81, 5932 (1998) Entanglement: a) Generation b) Distribution c) Purification d) Swapping e) Storage

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