1. Not finding help here? Sign up for a free 30min 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!

How to get the matrices in partial trace

  1. Jun 28, 2016 #1
    1. The problem statement, all variables and given/known data
    Good day,

    I want to ask the matrix that obtained from below formula and example.

    $$tr_A(L_{AB})=\sum_i [(\langle i|\otimes id)L_{AB}(|i\rangle\otimes id)]$$

    this formula above can be represented as in matrix form below,

    $$tr_A(L_{AB})= \left(\array{1&0&0&0\\0&1&0&0}\right)\cdot \left(\array{0&0&1&0\\1&0&0&0\\0&0&0&0\\0&0&0&0} \right)\cdot \left( \array{1&0\\0&1\\0&0\\0&0}\right)=\left(\array{0&0\\1&0} \right)$$

    My question are:

    1.what its mean by d in this formula? How can I get this d?

    2.How he get the first 2X4 matrix? I already calculate but I just get first row only. How it compute from the formula exactly?

    Thank you
     
  2. jcsd
  3. Jul 1, 2016 #2
    Can you give more information from where you took this example as it seems a little out of context.

    From what I see the i stands for the identity matrix, and id for the 0 matrix, the O with the cross stands for tensor product, and take into account that < | and | > come from bra - ket notation of vectors and covectors.

    This appears to be a formula for the trace of a matrix L_{AB} which I have no idea from where comes.
     
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook

Have something to add?
Draft saved Draft deleted



Similar Discussions: How to get the matrices in partial trace
  1. ?how to get there (Replies: 1)

Loading...