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

Basic question about Pauli Rotations

  1. Feb 8, 2007 #1
    So it's apparently possible to prove that e^{-iAx} = cos(x)I + isin(x)A given that A^2=I.

    What I don't understand is how this is supposed to be derived. Any help would be appreciated as this is driving me nuts and this is probably something that is very easy to prove...
  2. jcsd
  3. Feb 8, 2007 #2

    Dr Transport

    User Avatar
    Science Advisor
    Gold Member

    Ther are two ways, expand the exponential use the eigenvalues and eigenvectors of the matrix A.
  4. Feb 8, 2007 #3
    Ahh, I knew I was missing something stupid. I didn't realize that A^{2n}A = A.

    Thanks :)
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook