Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Expectation values

  1. Mar 26, 2015 #1


    User Avatar

    If I have the following expectation value for a general operator A < psi | cA | psi > where c is a complex constant and I want to take c outside the bracket does it go as c or its complex conjugate ?
  2. jcsd
  3. Mar 26, 2015 #2

    king vitamin

    User Avatar
    Gold Member

    You take c outside, and do not complex-conjugate it. You can always view the bra <psi| as a linear operator on kets, and since A|psi> is a ket bringing c outside is fine. Almost all operations in QM are linear, and complex constant can be taken outside of linear operators. When you deal with time-reversal, you introduce anti-linear operators where you do have to complex-conjugate constants to bring them outside, but this is not the case here.
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook