Hello,
I messaged a coupled months back on a basic question. I have another one. KWANT has been very useful to me so far, and I like to think I've made some progress with it, however, I still occasionally am tripping up on basic things. I'm sorry if the answer to this is obvious.
I am trying to create an SNS junction to study helical ABSs in a magnetic field, but I'm having some basic problems implementing the magnetic field in the code along with the Bogliubov deGennes equation. Using the tutorials and paper as my guide, I'm defining a global method for the hopping and have tried to use it in the system, without success. How would I implement it with the hoppings with the superconductor formalism, with separate leads for electrons and holes? Is there something I'm missing on how to do ityou can't just use the magentic field as the hopping, as in the examples. Would I just subtract it as a gauge from the Hamiltonian diagonal entries, as you do analytically? Is there an example out there for that?
At the moment, as a side question, when I try to simply to multiply the magnetic field with 4tmu, I'm getting a ValueError: that the hoppings then do not match the dimensions of the onsite Hamiltonian. So I'm guessing that's not the way of going about it.
Thank you.
Ian R George <iangeorge <at> utexas.edu> writes:
Hello, I messaged a coupled months back on a basic question. I have another one.
KWANT has been very useful to me so far, and I like to think I've made some progress with it, however, I still occasionally am tripping up on basic things. I'm sorry if the answer to this is obvious.
I am trying to create an SNS junction to study helical ABSs in a magnetic
field, but I'm having some basic problems implementing the magnetic field in the code along with the Bogliubov deGennes equation. Using the tutorials and paper as my guide, I'm defining a global method for the hopping and have tried to use it in the system, without success. How would I implement it with the hoppings with the superconductor formalism, with separate leads for electrons and holes? Is there something I'm missing on how to do ityou can't just use the magentic field as the hopping, as in the examples. Would I just subtract it as a gauge from the Hamiltonian diagonal entries, as you do analytically? Is there an example out there for that?
At the moment, as a side question, when I try to simply to multiply the
magnetic field with 4tmu, I'm getting a ValueError: that the hoppings then do not match the dimensions of the onsite Hamiltonian. So I'm guessing that's not the way of going about it.
Thank you.
I figured out how to implement the magnetic field in the programI was just being incredibly stupid/sleepy last nightbut I would still like to know if I should put the magnetic gauge in the leads or not, as well as the Hamiltonian and the hoppings. There would be some effect, I guess, on the infinite leads of the system, but in order to see what I want, should I just assume it is idealthe conductance is completely suppressed if I do it.
Ian R George <iangeorge <at> utexas.edu> writes:
Hello, I messaged a coupled months back on a basic question. I have another one.
KWANT has been very useful to me so far, and I like to think I've made some progress with it, however, I still occasionally am tripping up on basic things. I'm sorry if the answer to this is obvious.
I am trying to create an SNS junction to study helical ABSs in a magnetic
field, but I'm having some basic problems implementing the magnetic field in the code along with the Bogliubov deGennes equation. Using the tutorials and paper as my guide, I'm defining a global method for the hopping and have tried to use it in the system, without success. How would I implement it with the hoppings with the superconductor formalism, with separate leads for electrons and holes? Is there something I'm missing on how to do ityou can't just use the magentic field as the hopping, as in the examples. Would I just subtract it as a gauge from the Hamiltonian diagonal entries, as you do analytically? Is there an example out there for that?
At the moment, as a side question, when I try to simply to multiply the
magnetic field with 4tmu, I'm getting a ValueError: that the hoppings then do not match the dimensions of the onsite Hamiltonian. So I'm guessing that's not the way of going about it.
Thank you.
I forgot to ask this in the previous message. My apologies. Is it generally OK to define the magnetic field inside the make_system routine as opposed to a global method, if it works for your purposes, or are their risks to this.
Dear Ian,
None of us are really available right now, so I will just drop a couple of lines, if it is not enough please reask in a couple of weeks.
Yes you should probably add the magnetic field in the leads: if you don't the abrupt change of field will induce back scattering. You can do it locally it is always safer than globally. Gauge invariance on a lattice takes the following form: the pase accumulated on any given loop should be equal to the total flux through the corresponding surface. Any hopping that gives you that is ok. Beware that for BDG Hamiltonian, Holes are time reversed with respect to electrons.
All the best, Xavier
________________________________________ De : Kwantdiscuss [kwantdiscussbounces@kwantproject.org] de la part de Ian George [iangeorge@utexas.edu] Envoyé : mardi 12 août 2014 11:20 À : kwantdiscuss@kwantproject.org Objet : Re: [Kwant] Help on a basic issue
Ian R George <iangeorge <at> utexas.edu> writes:
Hello, I messaged a coupled months back on a basic question. I have another one.
KWANT has been very useful to me so far, and I like to think I've made some progress with it, however, I still occasionally am tripping up on basic things. I'm sorry if the answer to this is obvious.
I am trying to create an SNS junction to study helical ABSs in a magnetic
field, but I'm having some basic problems implementing the magnetic field in the code along with the Bogliubov deGennes equation. Using the tutorials and paper as my guide, I'm defining a global method for the hopping and have tried to use it in the system, without success. How would I implement it with the hoppings with the superconductor formalism, with separate leads for electrons and holes? Is there something I'm missing on how to do ityou can't just use the magentic field as the hopping, as in the examples. Would I just subtract it as a gauge from the Hamiltonian diagonal entries, as you do analytically? Is there an example out there for that?
At the moment, as a side question, when I try to simply to multiply the
magnetic field with 4tmu, I'm getting a ValueError: that the hoppings then do not match the dimensions of the onsite Hamiltonian. So I'm guessing that's not the way of going about it.
Thank you.
I forgot to ask this in the previous message. My apologies. Is it generally OK to define the magnetic field inside the make_system routine as opposed to a global method, if it works for your purposes, or are their risks to this.
________________________________________ De : Kwantdiscuss [kwantdiscussbounces@kwantproject.org] de la part de Ian George [iangeorge@utexas.edu] Envoyé : mardi 12 août 2014 11:20 À : kwantdiscuss@kwantproject.org Objet : Re: [Kwant] Help on a basic issue
Ian R George <iangeorge <at> utexas.edu> writes:
Hello, I messaged a coupled months back on a basic question. I have another one.
KWANT has been very useful to me so far, and I like to think I've made some progress with it, however, I still occasionally am tripping up on basic things. I'm sorry if the answer to this is obvious.
I am trying to create an SNS junction to study helical ABSs in a magnetic
field, but I'm having some basic problems implementing the magnetic field in the code along with the Bogliubov deGennes equation. Using the tutorials and paper as my guide, I'm defining a global method for the hopping and have tried to use it in the system, without success. How would I implement it with the hoppings with the superconductor formalism, with separate leads for electrons and holes? Is there something I'm missing on how to do ityou can't just use the magentic field as the hopping, as in the examples. Would I just subtract it as a gauge from the Hamiltonian diagonal entries, as you do analytically? Is there an example out there for that?
At the moment, as a side question, when I try to simply to multiply the
magnetic field with 4tmu, I'm getting a ValueError: that the hoppings then do not match the dimensions of the onsite Hamiltonian. So I'm guessing that's not the way of going about it.
Thank you.
I forgot to ask this in the previous message. My apologies. Is it generally OK to define the magnetic field inside the make_system routine as opposed to a global method, if it works for your purposes, or are their risks to this.
participants (3)

Ian George

Ian R George

WAINTAL Xavier