A's measurement Spin axis snaps: ŝ₀ → â Consequence for B Channel carries rotation: −ŝ₀ → −â ŝ₀ â −ŝ₀ −â Before channel signal B axis = −ŝ₀ (random) After channel signal B axis = −â (definite) R(−ŝ₀) = −R(ŝ₀) = −â Linearity of rotations: the identity holds for all θ_A
60°