10월의 물리학자들 (벨 부등식).pdf

1. Bell’s inequalities that all local realistic theories obey and quantum theory can violate â b̂ 2  ha1b1i + ha1b2i + ha2b1i ha2b2i  2 Bell, Physics 1, 195 (1965); CHSH, PRL 23, 880 (1969)

2. Quantum theory can violate Bell’s inequality hâb̂i ⌘ h |âb̂| i = cos ✓(~ a,~ b) hB̂i = hâ1b̂1i + hâ1b̂2i + hâ2b̂1i hâ2b̂2i ~ a1 ~ a2 ~ b1 ~ b2 hB̂i = 1 p 2 + 1 p 2 + 1 p 2 ✓ 1 p 2 ◆ = 2 p 2 > 2