2. Entanglement purification protocol (EPP) (EPP based on CNOT gates WF=F|y)〈|+ y+) +)(+|+ 小B1(B/B+vAV)B) AB (|H)AV)B±V)A|H)B B:|+)→+),B;)→,B:+→ Charles H. Bennett. et al., Phys. Rev. Lett. 76, 722 (1996)
(1) EPP based on CNOT gates Charles H. Bennett. et al., Phys. Rev. Lett. 76, 722 (1996) 2. Entanglement purification protocol (EPP)
Alice Bob Source pair 1/0H Target pair Classical communication before after keep ? source target source target )1+)|同 n. c yes 1〉1+)1+)m.c)|v )1v+)1)(n)|+ 士 )(nc)lo+) yes )1-)1)1-)yes )1-)1千)|-) )1-)1千 干 yes
Alice ES B 1/0 改进的CNOT门纯化方案 D Deutsch et al., Phys. Rev. Lett. 77, 2818(1996
B2 A1 B1 A2 Alice Bob 1/0 ES 1/0 UB UA UB UA 改进的CNOT门纯化方案 D. Deutsch et al., Phys. Rev. Lett. 77, 2818 (1996)
(2) EPP based on linear optical elements Alice Bob a3 a1 Pair 1 b1 b3 PBS PBS +/a4 82 Pair 2 b2 b4 Classical communication ab(中+ pab=F|+)ab(++(1-F)y+)ab(+ (HaH)b+valv)b) b (Have+Va h)b J w Panet al., Nature 410, 1067(2001)
(2) EPP based on linear optical elements J. W. Pan et al., Nature 410, 1067 (2001)
(3 EPP based on spatial entanglement Mirror al bl PBS PBS a2 a2 b2 b2 Pump HPDC=y(aibi +aibi+red(a2hbrH+a2vb2v)]+Hc 单对光子:(aPb1B+a1biv+a2b2+a2yb2)0) 两对光子:(ab+n+aib+a2b21+a2b2y2 C. Simon, Jian-Wei Pan, Phys. Rev. Lett. 89, 257901(2002)
(3) EPP based on spatial entanglement 单对光子： 两对光子： C. Simon, Jian-Wei Pan, Phys. Rev. Lett. 89, 257901 (2002)