1. Limited time only! Sign up for a free 30min personal tutor trial with Chegg Tutors
    Dismiss Notice
Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Homework Help: Why is <n|n-2> = 0?

  1. Jan 23, 2015 #1
    1. The problem statement, all variables and given/known data

    This is not really homework. I'm just studying and came across this question. So, I'm not sure if I should post this question here on one of the physics sections.

    On computing ##<n|\hat{a}^2|n>##, one arrives at ##\sqrt{n}*\sqrt{n-1}<n|n-2>=0## because ##<n|n-2>=0##

    Now, why is that so?
  2. jcsd
  3. Jan 23, 2015 #2
    Isn't that just because the two Fock states are orthogonal?
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook

Have something to add?
Draft saved Draft deleted