Hi!
I have a problem with the phases of my spectrum. One way I received the correct spectrum was by a loop that takes multiple spectra with different amount of time steps and averages the spectrum by the number of total spectra.
But I think there is an easier way to solve this. And I think it could be done by removing coherences. So how can I extract populations and coherences separately? Meaning the diagonal and undiagonal elements of the density matrix. Is there maybe a function for this? I thought that coherence.m and/or correlation.m could be used, but it seems that coherence  and correlation orders are a different thing.
Once again, many thanks.
Coherence
Re: Coherence
Well, yes, coherence() and correlation() filter specific coherence and correlation orders.
https://spindynamics.org/wiki/index.php ... oherence.m
https://spindynamics.org/wiki/index.php ... relation.m
The difference is that coherence order is an eigenstate of the total Lz operator with a particular multiple of the frequency, and correlation order is the number of nonunit Pauli matrices in the direct product state.
https://spindynamics.org/wiki/index.php ... oherence.m
https://spindynamics.org/wiki/index.php ... relation.m
The difference is that coherence order is an eigenstate of the total Lz operator with a particular multiple of the frequency, and correlation order is the number of nonunit Pauli matrices in the direct product state.

 Posts: 12
 Joined: Tue May 24, 2022 6:32 am
Re: Coherence
Thank you for the answer, I might have been a bit unspecific in my first question.
Is there a way to extract populations and coherences, diagonal and offdiagonal, of the density matrix in the eigenbasis of the hamiltonian?
Is there a way to extract populations and coherences, diagonal and offdiagonal, of the density matrix in the eigenbasis of the hamiltonian?
Re: Coherence
Well, sure  choose Hilbert space as formalism, get the Hamiltonian, diagonalise it, transform your density matrix into its eigenframe, and just use Matlab indexing to extract the elements of the matrix.