Applicability of Kwant to time-dependent gating of a TMDC quantum dot

To whom it may concern, I am a graduate student at the University of Illinois at Chicago (UIC) and I am interested in studying qubit manipulation in single and double quantum dots made from TMDCs. Specifically, I am interested in simulating a type of qubit/quantum dot configuration which was proposed in the following paper: https://iopscience.iop.org/article/10.1088/1367-2630/ab5ac9 I noticed that Kwant does seem to allow for time-dependent electric fields in its calculations but I wasn't sure if it could handle this specific type of problem.
What I would like to know is the following: 1. Is Kwant capable of simulating a quantum dot similar to the one proposed in the linked paper 2. If not, what kind of modifications would I need to make to the code to make it possible for it to accurately simulate the proposed structure
Thank you for your time, John Tiessen

Hi John,
When dealing with quantum dots, I think you're usually interested in the quasi-adiabatic approximation, when only a few levels are ever occupied, and dealing with the effective time-dependent Hamiltonian of those levels. If this is indeed your case, I recommend to look at our recent work (https://arxiv.org/abs/1909.09649), where we implement the Lowdin partitioning algorithm for computing an effective few-level Hamiltonian starting from the microscopic Kwant model. The associated code is published on Zenodo.
Alternatively, if you want to simulate the complete time evolution of the full wave function, there's the package t-kwant that is now being prepared for release (https://gitlab.kwant-project.org/kwant/tkwant).
Let me know if that helps, and if you have any further questions.
Best, Anton
On Mon, 18 May 2020 at 17:04, tiessen2@uic.edu wrote:
To whom it may concern, I am a graduate student at the University of Illinois at Chicago (UIC) and I am interested in studying qubit manipulation in single and double quantum dots made from TMDCs. Specifically, I am interested in simulating a type of qubit/quantum dot configuration which was proposed in the following paper: https://iopscience.iop.org/article/10.1088/1367-2630/ab5ac9 I noticed that Kwant does seem to allow for time-dependent electric fields in its calculations but I wasn't sure if it could handle this specific type of problem.
What I would like to know is the following:
- Is Kwant capable of simulating a quantum dot similar to the one proposed in the linked paper
- If not, what kind of modifications would I need to make to the code to make it possible for it to accurately simulate the proposed structure
Thank you for your time, John Tiessen

Hello Anton,
I'll need to read through these papers more carefully, but so far they look promising! When you say the code is published on Zenodo, do you mean this webpage: https://zenodo.org/record/3560075#.XsK1KMBOlPY
Do you have any idea when t-kwant will be released and/or a paper will be published on it?
Thank you for you assistance, John

Hi John,
Tkwant should be released in 2 months or so, possibly less, together with a paper. But I think, you should go with what Anton suggests. Tkwant might become useful when the leads play a significant role.
Best, Xavier
________________________________________ De : tiessen2@uic.edu [tiessen2@uic.edu] Envoyé : lundi 18 mai 2020 18:26 À : kwant-discuss@python.org Objet : [Kwant] Re: Applicability of Kwant to time-dependent gating of a TMDC quantum dot
Hello Anton,
I'll need to read through these papers more carefully, but so far they look promising! When you say the code is published on Zenodo, do you mean this webpage: https://zenodo.org/record/3560075#.XsK1KMBOlPY
Do you have any idea when t-kwant will be released and/or a paper will be published on it?
Thank you for you assistance, John

I'll need to read through these papers more carefully, but so far they look promising! When you say the code is published on Zenodo, do you mean this webpage: https://zenodo.org/record/3560075#.XsK1KMBOlPY
Yep, that's the one.
There are several papers describing the t-kwant formalism, I'll leave it to the t-kwant authors to name the most relevant source.
Best, Anton
Do you have any idea when t-kwant will be released and/or a paper will be published on it?
Thank you for you assistance, John

Great! Thanks for the help! If we end up using your software to perform the simulations I'll be sure to come back here if we have any problems or if we need to make additions to the code.
participants (4)
-
Anton Akhmerov
-
John Tiessen
-
tiessen2@uic.edu
-
WAINTAL Xavier