Dear Sir,
I am a PhD student of Hong Kong University of Science and Technology. I
want to use KWANT to caculate Hall resistance of a Hall bar structure.We
can get the conductance between 6 electrodes, but how to get hall
resistance? Can you give me some help? Thank you very much.
Best Regards,
Zhang Bing

Dear all,
I am using Kwant to study a system with both spins and electron and hole,
so the hopping matrix is 4X4. Now I want to know how to separate the spins,
electron and hole. I study this through the "2.6. Superconductors: orbital
degrees of freedom, conservation laws and symmetries"
smatrix = kwant.smatrix(syst, energy)
data.append(smatrix.submatrix((0, 0), (0, 0)).shape[0]
-smatrix.transmission((0, 0), (0, 0)) +smatrix.transmission((0, 1), (0, 0)))
I do not find more information about this for kwant.
For my system, if I have 3 leads, and the hopping and onsite energy is set
in this order:
(e↑,0,0,0)- spin up electron,first row of the 4X4matrix
(0,e↓,0,0)- spin down electron,second row of the 4X4matrix
(0,0, h↑ ,0)- spin up hole,third row of the 4X4matrix
(0,0, 0, h ↓ )- spin down hole,fourth row of the 4X4matrix
I want to obtain the transmissions from 0 →2.
smatrix = kwant.smatrix(syst, energy)
The transmission from h↑ to e↑ is: smatrix.transmission((2, 1), (0, 2))
The transmission from h ↓ to e↑ is: smatrix.transmission((2, 1), (0, 3))
Is my understanding correct?
Thanks very much in advance!
Hosein Khani

Dear users,
I am a Physics Masters student and am using tkwant to simulate braiding (adiabatic exchanging) of Majorana fermions in a 2D system. Currently, even for the smallest systems, although these do work using Jupyter, I get a memory error when using my university's HPC supercomputer and MPI ranks. Also, when running simulations on Jupyter notebook (supercomputer client) any large-ish system never actually completes.
More specifically, my issue seems to lie with 'wave_function.evolve' and 'wave_function.evaluate' for the time for loop.
density_operator = kwant.operator.Density(syst, np.eye(8)).bind(params=params)
wave_function = manybody.WaveFunction(psi_init, tasks)
for time in times:
wave_function.evolve(time)
density = wave_function.evaluate(density_operator)
densities.append(density)
plt.plot(sites, density - density0, label='time={}'.format(time))
In my system, I have 4 time-dependent gates and they are supposed to turn on and off according to what time the system is in. I have used 'if' statements to specify when the gates should be on or off.
If anyone can help it would be of great help. Thank you.

Dear All
I am Jiayin Gu, now a postdoc researcher in Peking University. I am interested in the package Kwant. Since I am a very beginner in front of this package. I want to ask that whether Kwant is capable of performming full counting statistics for a quantum transport system. If it can, could someone indicate a research paper on this. Thanks in advance!
Best regards
Jiayin Gu

Dear Cemal Basaran
I read your article, it was very interesting.
I want to reproduce the results you obtained in the article you
published, but my results are a little different and there is probably a
problem with my simulation. Can you give me the source code for this
article?
Thanks
Javad Tavakkoli
> M.Sc student
> Department of Physics
> University of Tehran
> hmoshfegh(a)ut.ac.ir

This is more of a physical question.
I am considering a system set up of a superconductor connected to a non-superconducting metal. As in: [Lead][Conductor][Superconductor]
In Kwant I set the superconductor up with an electron lattice and a hole lattice.
I can simulate this is two ways; one is the superconductor as a lead, and the other is the superconductor as part of the scattering system.
So, [Lead][Conductor Region][Superconducting Lead] or [Lead][Conductor Region][Superconductor Region]
If I look at the conduction between the electron and the hole lead on the left leads, I simulate slightly different conduction values for the case of the SC in the scattering region and the SC as a lead on the right side.
Physically, as I understand it, there should be basically no difference at least at low enough energy values. Is the slight difference due to this "low enough energy" threshold, or am I missing something physical or numerical from kwant that would cause this difference to exist regardless?

Dear Kwant user,Good day. I am notgetting the idea where and where not to
use theconservation_lw=-sigma_z in spinful Hamiltonian. For instance in
theTutorial 2.3.2. Spatially dependent values through functions,
thehamiltanian is spinful but the conservation law was not set while
computing the conductance. The same thing in the tutorial of
Quantumanomalous Hall effect where the local current is plotted without
highlighting the conservation law.
However, in the case of magnetic texture tutorial the conservation law was
set as-sigma_z. Additionally, in some discussion ( kwant mailing list)
about up/down conduction you have urged to set the conservation law to
be-sigma_z instead of using two different lattices (up-lattice
ansdown-lattice).
My question is why we have not used the conservation law in the first two
examples.
In fact, I am calculating the current flow in a region where I have
included some interactions such as intrinsic spin-orbit coupling, Rashba
SOC and Pseudo inversion asymmetric SOC. So do I need to provide the type
of conservation law or not.
Additionally, is there a way to calculate the current in parallel since the
energy isone value. I mean the current for a given energy. So I am not
getting the idea how to set parallel calculation in the case of current.
I do thank for your time and support
Regards
Adel BELAYADI

Hello all,
I am interested to work with quantum transport using kwant in 2D
heterostructure.
I want to create mono and bilayer of MoS2, and also introduce doping of
oxygen in that.
For that reason, I am seeking help from your group as it is not available
in the API.
waiting for your reply,
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With regards,
Ritwick Sarkar.
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