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I Phase of |0> when it appears in a product

  1. Apr 20, 2017 #1
    In a beam splitter with one vacuum input, the output looks like ##\frac{1}{\sqrt 2}(|1_A\rangle +i|0_B \rangle)\frac{1}{\sqrt 2}(-i|1_A\rangle +|0_B \rangle)##.
    If there is some further processing, the vacuum ##i|0_B\rangle##, along with the i , could end up multiplied with some non-vacuum term.

    Do we need to keep track of that "i" that originates from such a vacuum term? If so, what is the physical interpretation?
  2. jcsd
  3. Apr 20, 2017 #2


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    Please make it a habit to cite your sources and explain your notation.

    The state you have given doesn't make sense to me. Are you really familiar with what a products of ket vectors signifies?
  4. Apr 20, 2017 #3
  5. Apr 20, 2017 #4
    Actually, they do keep track of the vac term in that reference so I guess that answers my question.
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