Unformatted text preview: eigenstates (the standard “Copenhagen interpretation” of QM). 2, 3. Bransden 13.15 (counts as 2 problems) 4. In class we showed for pure states that ˆ ρ 2 = ˆ ρ , by working in the basis where ˆ ρ is diagonal. Show for yourself that if ˆ ρ represents a mixed state made up of orthogonal pure states α 1 ,α 2 ,...,α m with nonzero probabilities W 1 ,W 2 ,...,W m , m > 1, then ˆ ρ 2 6 = ˆ ρ by working in an appropriately chosen basis. (This result also holds if the constituent pure states are not orthogonal, but you need not treat this case.) 1...
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 Fall '07
 MOORE
 Physics, mechanics, Quantum decoherence, pure states, density matrices, spinhalf operators Sz

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