Dear all, i used a slightly modified "discretize.py" code of https://kwant-project.org/doc/1/tutorial/discretize (see attached file) and added the term """ + kappa * kron(sigma_z,sigma_0) """ to the hamiltonian (splitting up the different spins). When checking the unitarity of the scattering matrix at energy=0 by applying the function "check_unitarity(matrix)" for kappa=0 and kappa=10**(-9) the unitarity-error is increasing from order 10**(-13) to 10**(-6) ! Why is the error of $ S^\dagger S$ getting so high? Thanks in advance! Andreas Bereczuk
Dear Andreas,
I investigated your code and everything seems correct.
I checked your claim, and found it true!
For large value kapp=0.0001, the S matrix is unitary. The same for Kappa=0
or kappa <1E-13. Around Kappa=1E-9, it is not unitary (at least not unitary
with the precision set in kwant)
I am still puzzled and did not find an answer for that. The only remark I
can make is that the edge state at this energy is degenerate and I
remember, a case with kwant having a problem happening at the degenerate
states.
If it happens that you find the answer, I will be interested to read it.
Best regards,
Adel
On Thu, Dec 10, 2020 at 5:49 PM Andreas Bereczuk
Dear all,
i used a slightly modified "discretize.py" code of https://kwant-project.org/doc/1/tutorial/discretize (see attached file)
and added the term
""" + kappa * kron(sigma_z,sigma_0) """
to the hamiltonian (splitting up the different spins). When checking the unitarity of the scattering matrix at energy=0 by applying the function "check_unitarity(matrix)" for
kappa=0 and kappa=10**(-9) the unitarity-error is increasing from order 10**(-13) to 10**(-6) !
Why is the error of $ S^\dagger S$ getting so high?
Thanks in advance!
Andreas Bereczuk
-- Abbout Adel
participants (2)
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Abbout Adel
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Andreas Bereczuk