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Conditions on bloch variables

  1. Feb 14, 2015 #1
    1 qubit can be expressed as 1/2(I + n.σ). where n = (n_x,n_y,n_z) is a 3D vector, with size <=1. Hence the condition is that the sum of squares of the variables must be 1 or less. In the general expression of multi-qubit systems, we tensor product these individual qubits and also add the correlator terms. For example a 3 qubit general state will have 63 variables. The question is what are the conditions on these variables in order for it to be a valid density matrix ?
  2. jcsd
  3. Feb 19, 2015 #2
    Thanks for the post! This is an automated courtesy bump. Sorry you aren't generating responses at the moment. Do you have any further information, come to any new conclusions or is it possible to reword the post?
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