MATLAB Answers

Partial trace of matrix

84 views (last 30 days)
Nikolaos
Nikolaos on 21 Jul 2011
For a given density matrix which originates from a vector which contains four systems, i want to compute the reduced density matrix for each of the four subsystem. (i.e. I have a density matrix which has constructed from four subsystem outer products and I want to compute the partial trace of this matrix for each one of those subsystems).
I. I was wondering if there is an efficient way to do this

  0 Comments

Sign in to comment.

Accepted Answer

Jean-Daniel
Jean-Daniel on 22 Aug 2011

  0 Comments

Sign in to comment.

More Answers (1)

Nikolaos
Nikolaos on 25 Oct 2011
thx a lot.. but the problem is that this is not working for all cases. For example if you have tri-partite or four-partite systems. This is my way of making a partial trace of the initial matrix pall of dimensions 100x100 into the partial matrix pred of dimensions 10x10 according to pred(i,j)= Sum_ijkl pall(i,j,k,l)
red=zeros(10)
pd= reshape(pall, 10,10,10,10)
for ii=1:10
for jj=1:10
for mm=1:10
pred(ii,jj)=pred(ii,jj)+pd(ii,mm,jj,mm)
end
end
end

  0 Comments

Sign in to comment.

Sign in to answer this question.


Translated by